Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Analogue and numerical forward
modelling of sedimentary systems;
from understanding to prediction
9 – 11 October 2003
Abstract Volume
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Sponsors :
SHELL Research Rijswijk
NITG-TNO
Utrecht University
NSG
IAMG International Association for Mathematical
Geology
International Association of Sedimentologists
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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Utrecht, 9 – 11 October 2003
Contents
Contribution
Page
POROSITY PREDICTION THROUGH MICRO-SCALE SIMULATION OF GRAIN
REARRANGEMENT ........................................................................................................................................... 7
ALBERTS, L. ........................................................................................................................................................ 7
2D AND 3D SUBSIDENCE ANALYSIS IN A COMPLEX FORELAND BASIN: THE VENETIAN
BASIN (NE ITALY). ............................................................................................................................................. 8
BARBIERI C. 1 & GARCIA-CASTELLANOS D. 2 .................................................................................................... 8
QUANTITATIVE 3D MODELING OF SEDIMENTARY TRANSPORT MECHANISMS IN THE PERIALPINE FOREDEEP (UPPER MARINE MOLASSE, LOWER MIOCENE) .............................................. 10
BIEG, U.1, SUESS, M.P.1, KUHLEMANN, A. 1 & THOMAS, M. 2 ........................................................................ 10
MODELING ALLUVIAL DEPOSITS .............................................................................................................. 11
BRIDGE, J. ......................................................................................................................................................... 11
LIMITS TO PREDICTABILITY ARISING FROM NON-LINEAR AND CHAOTIC BEHAVIOUR:
RESULTS FROM A NUMERICAL STRATIGRAPHIC FORWARD MODEL OF CARBONATE
SYSTEMS ............................................................................................................................................................. 13
BURGESS, P.1 & EMERY, D.2 ............................................................................................................................. 13
FROM QUINCUNX TO DELTA: A STOCHASTIC CELLULAR AUTOMATA APPROACH TO THE
CREATION OF FANS, VOLCANOES AND DELTAS.................................................................................. 14
BURROUGH, P. .................................................................................................................................................. 14
MODELLING OF THE MIDDLE TO LATE PLEISTOCENE RHINE-MEUSE SYSTEM IN THE
CENTRAL NETHERLANDS ............................................................................................................................ 15
BUSSCHERS, F.S. & VAN BALEN, R.T. .............................................................................................................. 15
THREE-DIMENSIONAL MODELLING OF THRUST-CONTROLLED FORELAND BASIN
STRATIGRAPHY ............................................................................................................................................... 16
CLEVIS, Q. ........................................................................................................................................................ 16
MODELLING THE STRATIGRAPHY AND PRESERVATION POTENTIAL OF MEANDERING
STREAM DEPOSITS .......................................................................................................................................... 17
CLEVIS, Q. & TUCKER, G. ................................................................................................................................ 17
NUMERICAL AND ANALOGUE MODELLING OF SEDIMENTARY BASIN FORMATION ............. 18
CLOETINGH, S., GARCIA-CASTELLANOS, D., TER VOORDE, M. & SOKOUTIS, D. ......................................... 18
FORWARD MODELING OF MEANDERING CHANNELIZED RESERVOIRS ...................................... 19
COJAN, I., LOPEZ, S. & RIVOIRARD, J. ............................................................................................................. 19
PALEOZOIC BASIN STUDY: STRUCTURE, STRATIGRAPHY AND QUANTITATIVE MODELLING
IN THE SOUTHERN CANTABRIAN MOUNTAINS, NW-SPAIN ........................................................... 20
DIETRICH, B. .................................................................................................................................................... 20
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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QUANTIFIED CARBONATE PLATFORM DEVELOPMENT: THE ROSENGARTEN TRANSECT
(MIDDLE TRIASSIC, DOLOMITES) ............................................................................................................... 21
EMMERICH, A. ................................................................................................................................................. 21
INCORPORATION OF NUMERICAL AND PHYSICAL FORWARD MODELLING INTO
UNCERTAINTY ANALYSIS METHODS ....................................................................................................... 22
FEURER, J., & VAN DER ZWAN, C.J. ................................................................................................................ 22
ROLE OF FLUVIAL TRANSPORT DURING OROGENESIS: NEW NUMERICAL AND ANALOGUE
MODELLING TECHNIQUES .......................................................................................................................... 23
DANIEL GARCÍA-CASTELLANOS, KATARINA PERSSON, DIMITRIOS SOKOUTIS, IVONE JIMENEZ-MUNT ............ 23
A STRATEGY FOR AUTOMATED INVERSION OF PROCESS-BASED MODELS ..................................... 24
GEEL, C.R.& WELTJE, G.J. ............................................................................................................................... 24
3D SIMULATION OF SEDIMENTARY FACIES: APPLICATION TO LANGHIAN REEF BUILDUPS
IN VALLÈS-PENEDÈS BASIN (CATALUNYA). .......................................................................................... 25
GRATACOS, O. ................................................................................................................................................. 25
STRATIGRAPHIC FORWARD MODELLING OF DEEP MARINE SYSTEMS USING SEDSIM ........... 26
GRIFFITHS, C. ................................................................................................................................................... 26
THE TECTONIC EVOLUTION OF THE NORTHERN NORTH SEA FROM THE MID-JURASSIC
FORM 2D SUBSIDENCE ANALYSIS.............................................................................................................. 27
HANNE, D. ....................................................................................................................................................... 27
FINE-SCALE FORWARD MODELLING - EXAMPLE FROM A DEVONIAN REEF OF THE
CANNING BASIN ............................................................................................................................................. 28
MODELLING TURBIDITY CURRENTS BY CFD SIMULATIONS ............................................................ 29
HEIMSUND, S.1, 2, HANSEN, E.W.M.3, BAAS, J.H.4 & NEMEC, W.1 ................................................................ 29
FORWARD MODELLING & PREDICTION OF AEOLIAN SYSTEMS USING FUZZY LOGIC,
CONSTRAINED BY DATA FROM RECENT AND ANCIENT ANALOGUES........................................ 30
HERN, C.1, NORDLUND, U.2, ZWAN, C.J. VAN DER1 & LADIPO, K. 3.............................................................. 30
USING SUB-REGIONAL SCALE FORWARD MODELS TO CONDITION RESERVOIR-SCALE
STOCHASTIC SCENARIOS ............................................................................................................................. 31
HERN, C., LAMMERS, H., BURGESS, P. & NIJMAN, M. ................................................................................... 31
INVESTIGATION OF GRAVITATIONAL MASS TRANSPORT PROCESSES - USING THE DISTINCT
ELEMENT METHOD AS A MODERN TOOL IN SEDIMENT TRANSPORT MODELLING ................ 32
HUHN, K. & KOCK, I. ...................................................................................................................................... 32
MODELLING CYCLES OF FLUVIAL AGGRADATION AND DEGRADATION USING A PROCESSBASED ALLUVIAL STRATIGRAPHY MODEL ............................................................................................ 33
KARSSENBERG, D.1, BRIDGE, J.S.2, STOUTHAMER, E.1, KLEINHANS, M.G.1 & BERENDSEN, H.J.A.1 ............. 33
CHANNELISED TURBIDITY CURRENTS: NEW INSIGHTS INTO FLOW STRUCTURE AND
SECONDARY CIRCULATION ........................................................................................................................ 34
KEEVIL, G. ........................................................................................................................................................ 34
PREDICTING DISCHARGE AND SEDIMENT FLUX OF THE PO RIVER, ITALY SINCE THE LGM 35
KETTNER, A.J. & SYVITSKI, J.P.M.................................................................................................................... 35
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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MODELLING BEDDING AND PETROPHYSICAL CHARACTERISTICS OF TIDAL HETEROLITHIC
RESERVOIRS USING A PROCESS-ORIENTED APPROACH .................................................................... 43
MARTINIUS, A.W............................................................................................................................................. 43
TECTONIC CONTROL ON PAST CIRCULATION OF THE MEDITERRANEAN SEA ........................ 44
MEIJER, P.1, SLINGERLAND, R.2 & WORTEL,R.1 .............................................................................................. 44
NUMERICAL MODELING OF THE SEDIMENTARY SYSTEMS OF LARGE-SCALE COASTAL
SYSTEM TRACTS .............................................................................................................................................. 45
NIEDORODA, A.W., REED, C.W.1, DAS, H.1, DONOGHUE, J.2, FERRAGHAZZI, S.2 , WANG, Z.B.3 & STIVE,
M.4.................................................................................................................................................................... 45
3-D PHOTOREALISTIC MODELS OF GEOLOGIC OUTCROPS, A TOOL TO COLLECT
QUANTITATIVE DATA; METHODOLOGY AND HISTORIES EXAMPLES IN UTAH AND
WYOMING ......................................................................................................................................................... 47
OLARIU, C. ....................................................................................................................................................... 47
UPSCALING THE TIME PARAMETER IN STRATIGRAPHIC SIMULATION MODELS: EFFICIENT
USE OF HIGH-MAGNITUDE LOW-FREQUENCY EVENTS ..................................................................... 48
OVEREEM, I.1 & STORMS, J.2 ............................................................................................................................ 48
ANALOGUE MODELLING AS A TOOL FOR INVESTIGATING CAUSALITY IN ALLUVIAL
STRATIGRAPHY ............................................................................................................................................... 50
GEORGE POSTMA ............................................................................................................................................. 50
2D SUBSIDENCE MODELLING OF MIDDLE TRIASSIC CARBONATE PLATFORM
DEVELOPMENT IN THE LOMBARDIAN ALPS (ITALY) ......................................................................... 52
SEELING, M. ..................................................................................................................................................... 52
THE COMMUNITY SURFACE-DYNAMICS MODELING SYSTEM: AN ENVIRONMENT FOR
DEVELOPING, SHARING, AND USING SEDIMENT MODELS .............................................................. 53
SLINGERLAND, R. ............................................................................................................................................ 53
AVULSION, AUTOGENIC OR ALLOGENIC CONTROLLED? ................................................................ 55
STOUTHAMER, E. & BERENDSEN, H.J.A. ........................................................................................................ 55
VARIATION IN DIP OF LATERAL ACCRETION SURFACES IN SUBRECENT FLUVIAL DEPOSITS,
PANNONIAN BASIN, HUNGARY: A REFLECTION OF CLIMATIC FLUCTUATIONS OR JUST
MEANDERING EXCURSIONS? ...................................................................................................................... 56
SZTANÓ, O. 1 & MÉSZÁROS F. 2 ....................................................................................................................... 56
THE ROLE OF NUMERICAL SEDIMENTARY PROCESS MODELS IN HYDROCARBON
EXPLORATION AND RESERVOIR CHARACTERIZATION .................................................................... 61
TETZLAFF, D. ................................................................................................................................................... 61
MODELS THAT TALK BACK ....................................................................................................................... 62
TIPPER, J.C. ...................................................................................................................................................... 62
MODELLING THE IMPACTS OF CLIMATE CHANGE ON EROSION, SEDIMENT PRODUCTION,
AND LANDSCAPE EVOLUTION .................................................................................................................. 65
TUCKER, G. ...................................................................................................................................................... 65
SCALED MODELS OF SYNTECTONIC SEDIMENTATION – REVIEW OF PRINCIPLES AND FIRST
RESULTS ............................................................................................................................................................. 66
URAI, J.L. & KUKLA, P.A. ............................................................................................................................... 66
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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OUTCROP AND SEISMIC CONSTRAINTS FOR 3D NUMERICAL STRATIGRAPHIC FORWARD
MODELING ........................................................................................................................................................ 67
VAN BUCHEM, F., GRANJEON, D. & ESCHARD, R. ......................................................................................... 67
IMPACT OF DISCHARGE AND SEDIMENT FLUX ON BASIN MARGIN ARCHITECTURE: AN
EXPERIMENTAL APPROACH ....................................................................................................................... 69
VAN DEN BERG VAN SAPAROEA, A.P., POSTMA, G. & DALMAN, R.............................................................. 69
HIGH RESOLUTION 3D FORWARD STRATIGRAPHIC MODELLING OF CRETACEOUS
CARBONATE PLATFORM SYSTEMS............................................................................................................ 71
VAN DER ZWAN, C.J.1, MASSE, J.-P.2, BORGOMANO, J.1, 2, LAMMERS, H.1 & FENERCI-MASSE, M.2 ................. 71
COMBINATION OF STRUCTURAL BALANCING, REVERSE BASIN AND FORWARD
STRATIGRAPHIC MODELLING: SOUTHERN CANTABRIAN BASIN (NW-SPAIN) ......................... 73
VESOLOVSKY, Z. .............................................................................................................................................. 73
NON-UNIQUE SEQUENCE STRATIGRAPHIC ARCHITECTURES ........................................................ 74
WALTHAM, D., UDOFIA, M. & NICHOLS, G. .................................................................................................. 74
INSIGHTS INTO CARBONATE PLATFORM DROWNING MECHANISMS USING
STRATIGRAPHIC FORWARD MODELING................................................................................................. 75
WARRLICH, G. & BURGESS, P.M. .................................................................................................................... 75
MODELLING SOURCE ROCK DISTRIBUTION AND QUALITY VARIATIONS: THE NEW OF-MOD
3D TECHNOLOGY ............................................................................................................................................ 76
ZWEIGEL, J. ...................................................................................................................................................... 76
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Porosity prediction through micro-scale simulation of grain
rearrangement
Alberts, L.
Delft University of Technology, Department of Applied Earth Sciences, Mijnbouwstraat 120,
2628 RX DELFT, The Netherlands, l.j.h.albert@citg.tudelft.nl
Reservoir quality is commonly quantified in terms of the spatial distribution of
porosity and permeability, where the latter critically depends on the former.
Analytical methods of porosity prediction in natural sediments are not available, on
account of the difficulties of describing the geometrical arrangement of multi-sized
particles of irregular shape. Available techniques to estimate porosity are empirical
equations that predict an exponential decrease of pore volume as a function of
effective stress, or focus on cementation processes. Such methods do not incorporate
uncertainty or variability of estimates, because they are tailored to data collected in a
specific area. A more generally applicable method of porosity prediction is needed to
enhance the usefulness of process-based stratigraphic simulators for reservoir
modelling.
We have developed a numerical model that simulates the compaction of particle
populations at a micro-scale. The model comprises the interparticulate mechanics
that occur after deposition and during shallow burial, i.e. prior to the phase in which
chemical processes start to dominate compaction. Spatial continuity of the particle
pack is simulated through the use of periodic boundary conditions in X and Y,
whereas elastic boundaries ('cushions') are implemented in the Z direction. The
particle pack thus represents an infinite layer of limited thickness, much like a single
lamina. The grain-size distribution of the pack is the key parameter in the model. The
model is object based, which allows the mechanics of each particle to be calculated,
whereas the properties of the entire pack serve as global state variables during the
rearrangement. With this model we can simulate realistic trajectories of porosity
decline for natural particle-size distributions under several burial scenarios.
Calibration of the model to physical experiments and sensitivity analyses will be
discussed, to provide a basis for the evaluation of uncertainty in model predictions.
The resulting particle pack can be used for simulations of permeability, conductivity
and wave-propagation studies.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
2D and 3D subsidence analysis in a complex foreland basin: The
Venetian Basin (NE Italy).
Barbieri C. 1 & Garcia-Castellanos D. 2
Department of Earth Sciences, University of Pavia, via Ferrata 1, 27100 Pavia, Italy,
chiara.barbieri@manhattan.unipv.it
2 Department of Tectonics, Vrije Universiteit, de Boelelaaan 1085, 1081 HV Amsterdam, The Netherlands.
1
The Venetian basin (NE Italy) is characterized by a complex geometry due to the
partial superposition of three foredeeps, different in both age and polarity, associated
to the development of the surrounding belts, namely the Dinarides, the Eastern
Southern Alps and the Northern Apennines, which underwent their main orogenic
phases through Tertiary time. Therefore, it represents an interesting area to observe
and better understand the interplay between the evolution of mountain belts and the
response of the adjacent foreland.
The main goal of this work is to recognize and quantify the contribution of surface
loads (i.e. mountain belts, initial water depth, sedimentary infill) and of possible
deeper-sourced (hidden) loads, to the subsidence observed in the basin. This study
constitutes the base for the analysis of the sedimentary infill.
To this purpose, a former 2D flexural numerical modelling is applied along two key
transects trending NE-SW and N-S respectively, and a 3D flexural analysis is also
performed to solve possible misfits occurring in the sectors which have been
influenced by the combined effect of mountain belts.
Geological and geophysical data concerning the surrounding belts have been
collected from literature. In particular, data recently published in the context of the
TRANSALP project, together with previously available information on both
subsurface and surface studies, provide an accurate data set to study the effect of the
Eastern Southern Alps on the Venetian basin. Moreover, interpretation and depth
conversion of seismic lines and paleobathymetric analyses have been performed in
this work on some industrial transects and wells respectively (courtesy of ENI), to
integrate and improve the already existing data.
Two dimensional forward modelling has been performed according to the numerical
method discussed in Zoetemeijer et al. (1990). Gravimetric curves have been also
calculated to provide an independent constraint to test the reliability of the models,
which show the present geometries occurring in the basin. The model calculated on
the basis of NE-SW transect aims to test the flexural effect of the Dinaric belt which
underwent the main orogenic phases during Paleocene-middle Eocene. The best fit
has been obtained for a continuous plate condition and an Effective Elastic Thickness
value varying along section. Nevertheless, the tectonic phases occurred afterwards
with different direction make difficult to match all the points representing the base of
the Dinaric foredeep.
The second model, calculated along the N-S trending section, is focussed on the
flexure related to the main orogenic phases of the Eastern Southern Alps (late
Miocene-early Pliocene).
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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Utrecht, 9 – 11 October 2003
In this case a good fit has been obtained for a broken plate condition and a constant
Effective Elastic Thickness value of about 20 km. The resulting calculated flexure is
strongly influenced by the initial water depth and no hidden load was needed to fit
the observed flexure unlike a previously proposed model (Royden, 1993).
In spite of the good fit in front of the Eastern Southern Alps, a few metres high
forebulge is expected to the South from the model but it is not observed in the
present Adriatic Sea. In order to better understand the meaning of this mismatch, 3D
modelling has been applied by means of the software tao3D (Garcia-Castellanos,
2002).
To this purpose, flexure of the plate has been analysed in two steps by progressively
adding the loads due to the Eastern Southern Alps and the Northern Apennines.
Results show that a forebulge form in the same area as predicted by the 2D model if
the Northern Apennine load is not taken into account. Subsequently this bulge is
shifted to the South by the Apennine load and it migrates eventually toward the
Dalmatian region by including hidden loads, which are necessary to fit the flexure
presently observed in front of this belt.
In conclusion, on the basis of the calculated models, a forebulge would exist at the
end of Miocene in the area corresponding to the present Venetian coastline, which
subsequently migrated as a response to the Apennine-related flexure. This suggests
also that the Apennines would have affected the area of Venice since at least Pliocene
– early Quaternary.
Garcia-Castellanos D. (2002). Interplay between lithospheric flexure and river transport in
foreland basins. Basin Research, 14, 89-104.
Royden L. (1993). The tectonic expression slab pull at continental convergent boundaries.
Tectonics, 12, 2, 303-325.
Zoetemeijer, R., Desegaulx, P., Cloething, S., Roure, F. and Moretti, I., 1990. Lithospheric
dynamics and tectonic-stratigraphic evolution of the Ebro Basin. Journal of
Geophysical Research, 95, B3, 2701-2711.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Quantitative 3D modeling of sedimentary transport mechanisms in the
peri-Alpine foredeep (Upper Marine Molasse, Lower Miocene)
Bieg, U.1, Suess, M.P.1, Kuhlemann, A. 1 & Thomas, M. 2
1 University
of Tübingen, Department of Geoscience, Sigwartstr. 10, 72076 Tübingen, Germany
Ulrich.bieg@uni-tuebingen.de
2 Technical University of Dresden, Institute for Planetary Geodesy
At the Aquitanian-Burdigalian boundary the Molasse basin was flooded by a shallow
tide- and wave- dominated seaway, linking the Rhône Basin through, the peri-Alpine
foredeep with the Vienna Basin and thus with the eastern Paratethys. Mass
balancing of sediments derived from the developing alpine orogen and the foredeep
suggests a major export of sediments towards the West during the Upper Marine
Molasse (OMM, Burdigalian). Therefore it is of great interest which paleoceanographic processes were involved and potentially controlled the westwarddirected transport. The widespread occurence of meso- to macrotidal facies successions in the Molasse Basin adverts that tidal activity was a major force driving
paleocurrents. The aim of our study is therefore to provide a numerical model of
sediment particle transport conditions within a shallow-water environment.
We use QUODDY to model paleocurrents in this shallow foredeep. QUODDY is a
Fortran implementation of a 3-D finite-element shelf circulation model by the
Dartmouth College (Lynch & Werner, 1991; Lynch & Naimie, 1993; Lynch et al.
(1996). It is a free-surface, tide-resolving model based on conventional 3-D shallow
water equations. Atmospheric forcing terms for wind stress and temperature flux
can be implemented, as wells as point source terms for rivers and adjacent alluvial
plains.
Further boundary conditions of the tides in the Paratethys were obtained by calculating an initial tidal mode, based on a 1-degree reconstruction of the global
bathymetry in the Miocene. Based on paleogeographic data derived from Martel,
Allen & Singerland (1994) and new published palaeogeographic maps of the alpine
foredeep by Kempf & Kuhlemann (2002) we constructed an irregular triangular mesh
with a varying grid resolution, to describe the paleobathymetry of the basin.
First successful benchmarks were obtained by comparing with the model of Martel et
al. (1994).
Kuhlemann, J., Kempf, O. (2002): Post-Eocene evolution of the North Alpine Foreland Basin and its
response to Alpine tectonics; Sedimentary Geology, Vol. 152, pp 45 – 78.
Lynch, D.R., Werner, F.E. (1991): Three-dimensional hydrodynamics on finite elements. Part II: Nonlinear time-stepping model; Int. Numer. Meth. Fluids., 12, pp 507-533.
Lynch, D.R. and Naimie C.E. (1993): The M 2 tide and its residual on the outer banks of the Gulf of
Maine; J. of Phys. Oceanogr., Vol. 23.
Lynch D.R., Ip, J.T.C., Naimie, C.E., Werner, F.E. (1996): Comprehensive coastal circulation model
with application to the Gulf of Maine; Continental Shelf Research, Vol. 16, No.7, pp. 875-906.
Martel, A.T., Allen, P.A., Slingerland, R. (1994): Use of tidal-circulation modeling in the
paleogeographical studies: An example from the Tertiary of the Alpine perimeter; Geology, Vol.
22, pp 925-928.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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Utrecht, 9 – 11 October 2003
Modeling alluvial deposits
Bridge, J.
Binghamton University, Department of Geological Sciences, NY 13902-6000,Binghampton, United States,
jbridge@binghampton.edu
Understanding of fluvial sedimentary processes and deposits has come from field
studies of modern fluvial environments, laboratory flume studies, and construction
of idealized models based on these studies. Understanding and prediction of ancient
alluvial deposits is based on direct modern analogs and/or idealized models
(graphic or quantitative). Field studies of modern fluvial environments are difficult
to undertake during floods, over large areas, and for a long time, and it is difficult to
describe deposits below the water table. Recently, some of these problems have been
overcome by: using remote-sensing images and DEMs for studying changes in
channel and floodplain geometry; measurement of water flow and sediment
transport during floods using new types of equipment; description of deposits using
GPR in combination with coring, and OSL dating. Laboratory flumes have been used
to study fluvial processes and deposits over a wide range of physical scales.
However, scaling problems can limit the applicability of these studies to the real
world, and these problems increase as the scale of the physical model decreases
relative to the real-world prototype. In particular, all superimposed scales of
bedform and associated strata cannot be produced in flumes, and rates of
sedimentary processes are unrealistically high. Idealized models are ultimately
based on studies of modern sedimentary processes and deposits: therefore, shortterm, small-scale models are well developed and most easy to test. As the spatial and
temporal scale increase, useful models are more difficult to construct and test.
Linkages between models of different scales are also lacking. Quantitative models for
two scales of fluvial deposit are discussed here: deposits of alluvial valleys (or fans or
deltas) with channel belts and floodplains, and; deposits of channel belts.
The most common approach to modeling deposits of alluvial valleys (so-called
alluvial architecture) is: determine geometry, proportion and location of distinct
sedimentary bodies (objects) using well logs, cores, seismic or GPR; gain more
information from presumed outcrop analogs; use stochastic (structure-imitating)
models to simulate the geometry, orientation and location of objects between wells;
simulate rock properties within objects using stochastic models. Other types of
stochastic models are not object-based, and make use of transition
probabilities/Markov chains or indicator variograms. Problems with the stochastic
modeling approach include: difficulty in defining input parameters for the model;
over-reliance on outcrop analog data of dubious quality and usefulness; unrealistic
shapes and locations of objects; limited understanding of origin of deposits; no
predictive value outside data region. Stochastic models are used because commercial
software is available, simulations can be conditioned with available data (particularly
from wells and cores), and forward (process-imitating) models are considered to be
under-developed and very difficult to fit to subsurface data. However, forward
(process-based) models can give much better understanding of deposits and have
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
predictive ability beyond the data region. Furthermore, it is very likely that they can
be fitted to subsurface data by trial-and-error with optimization (inversion).
The simple 3-D alluvial architecture model of Mackey and Bridge (1995) has been
substantially developed by Karssenberg and others, and can now be considered to be
a quantitative 3-D fluvial sequence stratigraphy model. In addition to the processes
simulated by Mackey-Bridge, this new model simulates geometric evolution of the
channel network, upstream migration of knickpoints, incised channels and terraces,
and the effect of aggradation-degradation cycles on avulsion and alluvial
architecture.
Channel-belt deposits have also been simulated using object-based stochastic models:
however, existing models are very unrealistic, mainly because of poor definition of
object shapes and the methods for positioning objects. Deterministic quantitative
models that consider flow and sedimentary processes in channel belts are not very
well developed, and it is only possible to predict sedimentary details for individual
channel bar deposits. Further progress will be made as more information from
modern channel belts becomes available. Recent work of relevance to modeling
suggests that there are general relationships between the geometry of the different
scales of bedforms (e.g., ripples, dunes, bars) in rivers and the geometry of their
associated stratasets.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Limits to predictability arising from non-linear and chaotic behaviour:
results from a numerical stratigraphic forward model of carbonate
systems
Burgess, P.1 & Emery, D.2
1 Shell International Exploration and Production B.V., Postbus 60, 2280 AB Rijswijk, The Netherlands,
Peter.Burgess@shell.com
2 Dept. of Computing, University of Staffordshire
Most conceptual and indeed numerical models of sedimentary systems assume
simple linear behaviour, allowing straight forward prediction based on a relatively
simple relationship between cause and effect. However, another possibility for
sedimentary systems is non-linear behaviour leading to sensitive dependence and
perhaps to chaotic behaviour. For even tiny differences in some starting condition, a
system exhibiting sensitive dependence may produce quite different strata, a
phenomenon known as divergence. Such systems are not easily predictable; it is not
possible to predict the in detail the behaviour of such system over any time scale near
or beyond the divergence timescale. To investigate this possiblity, a numerical
stratigraphic forward model of a carbonate system with various non-linear
components has been used to generate autocyclic meter-scale shallowing-upward
parasequences and to investigate the consequences of sensitive dependence on initial
conditions for parasequence development. Two model Cases with only a very small
difference in initial starting topography have been run. Stratal patterns from the two
runs are similar in that both cases produce stacked parasequences with a similar
range of thicknesses and showing general shallowing upward trends. However,
thickness and facies distributions differ significantly in detail as a consequence of
divergence. Attempts to determine the Lyapunov exponent confirms that the model
exhibits divergence but suggests that it is not truly chaotic These results suggest that
we may be well advised to look for sensitive dependence and divergence in modern
and ancient systems, and to take account of possibility of such behaviour in
interpreting ancient strata; if real carbonate systems show similar divergence to these
model results, predictions from conceptual and numerical forward models should be
limited to general patterns unaffected by sensitive dependence.
- 13 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
From QUINCUNX to Delta: A stochastic cellular automata approach to the creation of
fans, volcanoes and deltas
Burrough, P.
University of Utrecht, Faculty Geosciences, Utrecht Centre for Environment & Landscape
Dynamics, Heidelberglaan 2, Utrecht, The Netherlands, p.burrough@geog.uu.nl
This presentation examines some useful stochastic models, including Francis Galton's
Quincunx (or regression) board, for explaining the statistical properties of
"sedimentary" structures like fans, deltas and volcanoes. This will be illustrated with
a critical examination of a set of dynamic models created in a dynamic GIS
environment. The paper will illustrate how well-known geological structures might
develop from purely stochastic processes driven by gravity. It will show how minor
variations and modifications of initial conditions can affect the detailed outcome of
the model but at the same time the generation of large numbers of stochastic
realisations demonstrates how easily variations on a generic theme can be arrived at,
thereby enhancing our understanding of geological variation in the field.
- 14 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Modelling of the Middle to Late Pleistocene Rhine-Meuse system in the
central Netherlands
Busschers, F.S. & Van Balen, R.T.
Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands,
freek.busscher@falw.vu.nl
The Saalian to Weichselian (OIS 6 to 2) Rhine-Meuse system in the central
Netherlands is a low-gradient fluvial system, located downstream of the hinge line of
the southern part of the North Sea basin. As a result, the deposits of the Rhine-Meuse
system (Kreftenheye Formation) consist of stacked coarse-grained packages of sand
and gravel. Results of multidisciplinary analyses of new high resolution cores allow
to construct a detailed model of the alluvial architecture of the Rhine-Meuse system.
In addition, over 80 OSL dates place the deposits in a well constrained chronological
framework. The cores are located along three large transects perpendicular to the
main paleoflow direction. The easternmost transect is situated close to the hinge line,
whereas the westernmost is close to the present-day coastline. A link to the offshore
sediments
is
in
progress
(4th
transect).
Our study shows that the Rhine-Meuse deposits consist of 6 to 7, 10-25km wide
stacked sediment bodies, formed during the last two glacial cycles. First results
indicate that the formation of bounding surfaces is related to climate (sediment
availability and discharge), glacio-eustacy and tectonic movements (glacio-isostacy).
These parameters also seem to control the grainsize distributions of the separate
sediment bodies. Modelling the alluvial architecture will allows us to infer the
relative importance of these controlling factors. This in turn will enhance predictions
of 3D grainsize distribution in this part of the Rhine-Meuse system, reducing the
costs for the exploration for sand and gravel in central Netherlands.
Modelling will first be done on a deltaic scale (100 km), focussing on the larger scale
trends in architecture and grainsizes. Subsequently, a smaller study area (5 km) will
be selected for high-resolution modelling.
- 15 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Three-dimensional modelling of thrust-controlled foreland basin
stratigraphy
Clevis, Q.
Oxford University, Mansfield Road, OX1 3TB, Oxford, United Kingdom, quintus.clevis@geog.ox.ac.uk
In this study we present a 3D forward stratigraphic model, which aids in the
interpretation of alluvial successions in foreland basins filled by axial-deltaic and
alluvial fan systems, under conditions of variable tectonism and eustatic sea-level
change. The first set of model experiments indicate that the onset of tectonic activity
is reflected by rapid retrogradation of both depositional systems, widespread
flooding and onlap of marine sediments. Syntectonic fluvial patterns on the axialdelta plain are dominated by bifurcating channels, swiftly relocating in response to
the general rise of relative sea level induced by flexural subsidence. The resulting
surface morphology of the axial delta is conical. Syntectonic eustatic sea-level
fluctuations result in parasequence-scale packages of retrograding and prograding
fan and deltaic sediments bounded by minor flooding surfaces and Type-2
unconformities.
Incised
channels
are
rare
within
the
syntec
tonic parasequences and are formed only during phases of tectonic quiescence when
eustatic falls are not longer compensated by the subsidence component in the rise of
relative sea level. Suites of amalgamating axial channels corresponding to multiple
eustatic falls delineate the resulting Type-1 unconformities. Coarse-grained, incised
channel fills are found in the zone between the alluvial fan fringes and the conical
body of the axial delta, as the axial streams tend to migrate towards this zone of
maximum accommodation.
Similar suites of amalgamating axial channel belts are created when the foreland
basin is detached from its substratum by a hinterland-dipping sole thrust and
transformed into a thrust-sheet top basin. This is shown in the second set of
experiments. Here, the competition between rates of regional flexural subsidence,
and local detachment-induced uplift controls the accommodation space evolution
and the stratigraphic patterns in the marine-influenced thrust-sheet top basin. Model
experiments show that displacement over low-angle faults (2~6 degr.) with moderate
rates (~5.0 m/kyr) results in a vertical uplift component sufficient to counteract the
background flexural subsidence rate. Consequently, the basin-wide accommodation
space is reduced, fluvio-deltaic systems carried by the thrust sheet prograde and part
of the sediment supply is spilled over towards adjacent basins. The intensity of the
forced regression and the interconnectedness of fluvial sheet sandstones increases
with the dip angle of the detachment fault.
- 16 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Modelling the stratigraphy and preservation potential of meandering
stream deposits
Clevis, Q. & Tucker, G.
Oxford University, Mansfield Road, OX1 3TB, Oxford, United Kingdom, quintus.clevis@geog.ox.ac.uk
The fluvial processes of floodplain aggradation, lateral stream migration and the
creation of cutt-offs have the potential to bury, obscure, expose, or even destroy
portions of meandering stream deposits, resulting in a complex subsurface mosaic of
sediments of a variety of ages and grainsizes. The aim of out study is to:
1)visualize the 3D spatial distribution of these meandering stream deposits and
2)quantify their preservation potential
as a function of the natural process of meandering, climatic change and human
influence, using the CHILD landscape evolution model. The landscape in the CHILD
model is represented by an adaptable triangular mesh of nodes, especially designed
for simulating the gradual shifting of meander bends. A new layer track routine is
currently added in order to improve the resolution of the stratigraphic record
accumulated by the model.
- 17 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Numerical and analogue modelling of sedimentary basin formation
Cloetingh, S., Garcia-Castellanos, D., Ter Voorde, M. & Sokoutis, D.
Free University Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands,
sierd.cloetingh@falw.vu.nl
Sedimentary basin systems provide an important source of information on the
mechanical properties of the underlying lithosphere.
At the same time, lithosphere rheology, appears to strongly affect the mode of basin
formation and associated vertical motions.
A close feed back exists between surface processes and deformation of the crustlithosphere lithosphere system at deeper levels.
The combination of numerical and analogue modeling has generated new insight in
the role of tectonic topography in source-sink relationships and drainage patterns.
Case studies from different basinal settings, including the Pannonian – Carpathen
system, the western Mediterranean and the Norwegian continental margin
demonstrate the importance of lithosphere memory in basin fill.
- 18 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Forward modeling of Meandering Channelized Reservoirs
Cojan, I., Lopez, S. & Rivoirard, J.
Ecole des Mines de Paris, 35, rue Saint Honoré, Fontainebleau, France, cojan@ensmp.fr
Ecole des Mines de Paris has developed a strong experience in the characterization of
heterogeneous reservoirs: Heresim pixel-based truncated and pluri-gaussian models,
Boolean object-based models, and studies of field analogs in various settings. This
expertise in geostatistics and in sedimentology is used to combine both stochastic
and process-based approaches in the modeling of fluvial meandering channels at the
oil reservoir scale.
The model is built from the spatial evolution of the channel in time, and the
deposition of the associated sedimentary bodies. The different elements have been
implemented taking into account physical results and case study reports. The 3D
evolution of the channel stems from equations developed in hydraulic studies and
proved to generate realistic 2D shapes. Developments have been added to account
for the longitudinal profile. A stochastic algorithm linked with physical parameters
allows to simulate chute cutoff, levee breaching and avulsions. Where appropriate,
the model makes it possible to generate the different deposits: point-bars, crevasse
splays, overbank alluvium, mudplugs and lowland deposits.
To be operational, the model is voluntarily controlled by a limited number of key
parameters. These allow to build and to test different architectures, e.g. making the
sinuosity and connectivity of sand bodies varying with avulsions frequency, or
reproducing external forcing (aggradation or incision). These key parameters can be
inferred from seismic or well data through the use of statistics, such as Vertical
Proportion Curves giving the proportions of facies along the vertical.
Finally, the resulting model is simple but robust and computationally fast.
Depending on a limited number of key parameters, yet capable to represent various
architectures, it can be used to produce one or multiple realizations of a reservoir, to
build detailed 3D blocks in order to test hypotheses on architecture, or to extract
training images, virtual wells. Conditioning lithofacies or granulometry, either
regionally or at well data, is to be obtained by favouring migration or avulsion of the
channel in preferential areas.
- 19 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Paleozoic Basin Study: Structure, Stratigraphy and Quantitative
Modelling in the Southern Cantabrian Mountains, NW-Spain
Dietrich, B.
University of Heidelberg, Im Neuenheimer Feld 234, D-69120, Heidelberg, Germany, birgit.dietrich@urz.uniheidelberg.de
A genetic model for a multi-phase structurally deformed basin is created by the
authors. The investigation area is located in the Southern Cantabrian Mountains of
northwestern Spain which belongs to the external part of the Variscan fold-andthrust belt. Intense thin-skinned thrusting has taken place during the Variscan
Orogeny. During the Alpine Orogeny, a second deformation event occurred which
locally overprinted the Variscan deformation by fault reactivation and development
of
out-of-sequence
thrusting.
However,
temperatures
were
low.
Two transects positioned in the direction of thrusting are being studied. The
stratigraphy to be modelled ranges from Cambrian to Carboniferous, focussing on
the Carboniferous. The Lower Paleozoic succession consists mainly of shallow
marine, siliciclastic sediments. Devonian mixed clastic-carbonate sedimentation
displays rapid lateral and vertical facies changes due to the development of ramps,
platforms and local basins.
The Carboniferous strata start with condensed successions, followed by carbonates
deposited in a progressively shallowing marine environment in front of the rising
Variscan Orogen. Distal turbidites of the Barcaliente Formation are succeeded by the
shallow carbonate ramp setting of the Valdeteja Formation. The upper part of the
ramp deposits interfingers with rapidly lateral changing flysch deposits of the San
Emiliano Formation. Allo- and biostratigraphy provide data to define time lines for
quantitative modelling.
Due to thrusting, the complete thickness of the Carboniferous succession is
unknown. Hence temperature data derived from vitrinite reflection measurements
aid in the interpretation.
Backward modelling is used as a dynamic, deterministic analysis of the development
of accommodation space. Subsequent to the backward modelling, dynamic,
stochastic forward modelling simulates sedimentation and transportation processes.
- 20 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Quantified Carbonate Platform Development: the Rosengarten Transect
(Middle Triassic, Dolomites)
Emmerich, A.
Geol.-Pal. Institute, University Heidelberg, Im Neuenheimer Feld 234, D-69120, Heidelberg, Germany,
emmerich@uni-hd.de
A combination of basin and stratigraphic modelling was carried out on the
Rosengarten platform (Schlern Formation) in order to quantify basin dynamics and
platform evolution. The essential data sets for stratigraphic reverse/forward (PHIL)
and basin modelling (PetroMod) were derived from existing studies and new
detailed analyses on facies architecture and thermal maturity.
We identified two major stages of platform evolution – the first one with high
subsidence rates and aggradational sedimentary characteristics and the second one
with low subsidence rates and strong progradational characteristics. The maximum
of the total subsidence was reached after the first biozone of platform growth 1100m/Ma in proximal and 1000m/Ma in distal parts. Then the subsidence slowed
down to values of about 50m/Ma to 150m/Ma. An explanation for the sudden stop
in subsidence is the coeval development of a huge magmatic chamber in the area of
Monzoni/Predazzo neighbouring the Rosengarten. Constant carbonate production
rates between 750m/Ma (platform slope) and 850m/Ma (platform top) were
determined by sequence stratigraphic forward modelling. These rates proved to be
sufficient to keep platform growth up with sealevel rise during times of high
subsidence and to produce fast progradation in the second stage of platform
evolution.
The mentioned modelling results are corroborated by the porosity evolution of the
sediment package below the slope mimicing the N-S trend of slope progradation.
Values of the regional vitrinite reflectance pattern in the underlying Permian lie
around 0.55%VRr. The temperatures during maximum burial (presumably during
Late Cretaceous times) most probably did not exceed 100°C. However, samples from
the Rosengarten area neighbouring the Monzoni volcanic centre reveal values
between 0.7 and 0.8%VRr indicating that the thermal influence of the Monzoni event
was restricted to its nearest vicinity. The next step of our investigations will be
pinpointing the timing of subsidence with the help of fission track analyses in
apatites.
- 21 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Incorporation of numerical and physical forward modelling into
uncertainty analysis methods
Feurer, J., & Van der Zwan, C.J.
SIEP-SEPTAR, EPT-AEP, P.O.Box 60, 2280 AB Rijswijk,
Jeurg.Feurer@SHELL.com
NL.
Kees.VanderZwan@SHELL.com,
Hydrocarbon occurrences rely on the concurrent presence of a valid structure,
hydrocarbon charge, a reservoir and a seal. The Oil Industry invests millions in the
predicting of these, in technology developments to improve prediction, and many
more millions in dry holes. Shell has a long tradition in Monte Carlo simulation to
manage subsurface uncertainty (e.g. uncertainty of porosity, closed rock volume,
etc), and is increasingly betting on the horse of forward modelling.
Although lithological predictions integrate various well-established disciples (e.g.
conventional and sequence stratigraphy, seismic stratigraphy, etc), the qualitative
and quantitative forecasts remain variably accurate and, at times, simply fall short on
consistency. Forward modelling is an effective means of improving both: the
consistency by encouraging geoscientists to synthesize the (limited) data into one or
more subsurface models, and the accuracy by simulating actual physical processes.
To date forward-modelling tools have remained largely deterministic. This bears the
inevitable consequence of undersampling the uncertainty space and deriving suboptimal statistics. The power of today’s computers is now sufficient to warrant the
development of probabilistic forward-modelling tools capable of processing multiple
alternative subsurface models.
In this presentation an overview will be given of current probabilistic oil industry
methodologies and how these models can be linked to best-fit and scenario-based
forward reservoir models.
- 22 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Role of fluvial transport during orogenesis: New numerical and analogue
modelling techniques
Daniel García-Castellanos, Katarina Persson, Dimitrios Sokoutis,
Ivone Jimenez-Munt
Free University Amsterdam
Erosion is a main process controlling the tectonic evolution of orogens, effecting on
their internal structure. Studies of the interplay between large-scale tectonics and
surface transport usually assume 2D (cross section) settings, whereas river networks
drive surface transport typically in the axial direction (parallel to the orogens). Do
the spatial asymmetries introduced by fluvial transport influence on the tectonic
deformation pattern during continental collision? The purpose of this work is to
evaluate the 3D interaction between lithospheric deformation and fluvial transport
during continental collision. For this purpose, we present results of two new
modeling techniques coupling a fluvial transport numerical model (stream power
approach) with a (left) numerical model of lithospheric viscous deformation
(thermally coupled thin-sheet approach) and a (right) analogue sandbox model of
upper-crustal deformation.
The Numerical Model fully couples a thermo-mechanical model of lithospheric
viscous deformation and fluvial erosion/deposition. The mutual feeback’s effects
between these processes are accounted for.
The hybrid Numerical-Analogue Model fully couples the dynamics of an analogue
deformation model (sand-box) and the fluvial transport numerical model. Both
components are linked via a scanner.
The results show that surface erosion, transport and sedimentation have a significant
effect on the distribution of lithospheric and crustal deformation during orogenesis.
The axial transport along the river network can induce lateral changes on the tectonic
evolution of orogen-basin systems, such as diachroneity. These effects are probably
less important than those induced by inherited heterogeneities and lateral changes in
the tectonic forcing.
- 23 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
A strategy for automated inversion of process-based models
Geel, C.R.& Weltje, G.J.
Department of Applied Earth Sciences, Delft University of Technology, Mijnbouwstraat 120, 2628 RX Delft,
The Netherlands, c.r.geel@ta.tudelft.nl
Application of process-based models in production geology has been hampered by
the difficulty of conditioning such models to well data. Several causes can be
indicated, of which irreversibility is the most important. The occurrence of erosion
surfaces prevents the application of a direct, simple inversion. Instead, a trial-anderror method or an automated goal-seeking algorithm must be employed. The fact
that most process-based models are CPU-intensive prohibits extensive trial-and-error
or automated goal-seeking approaches. Another fundamental problem is the choice
of an appropriate objective function, i.e. a criterion for quantifying the discrepancy
between a certain realisation and the well data. The ideal objective function should
be insensitive to local minima, while its value should be interpretable in probabilistic
terms. As these two aspects are difficult to reconcile, we have focused on the first
requirement.
In this paper we present a method that circumvents many of the above
problems. We use a very fast forward model, which can produce hundreds of
realisations in just a few minutes. At the same time, the model shows a sufficiently
rich behaviour to mimic the first-order dynamics of a shallow-marine environment.
The data to be matched are derived from permeability logs, as this quantity captures
most features of a given grain-size distribution in a single number. Permeability logs
are also readily available for oil wells, while quantities like grain-size distribution or
(litho) facies are usually not available. We use a modified Karman-Cozeny equation
to analytically determine permeability from grain-size distribution and porosity. The
latter is derived empirically from measurements on a series of lognormally
distributed coastal sands. Characteristic permeability-log shapes are converted into
character strings, from which the objective function value can be calculated. The
objective function itself is the Levenshtein distance widely used in spell checking,
speech recognition, DNA analysis, and plagiarism detection. A relatively
straightforward genetic algorithm is used to minimise this objective function.
The method was tested on a several (synthetic) cases with complicated, nontrivial geometries. Up to seven parameters related to oscillations of sea level and
sediment input could be inverted with a maximum error of 20% of their true value
within 45 minutes using an ordinary desktop PC. A typical seven-parameter
inversion requires about 50,000 iterations.
- 24 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
3D simulation of sedimentary facies: application to Langhian reef
buildups in Vallès-Penedès basin (Catalunya).
Gratacos, O.
Faculty of Geology, University of Barcelona, C/ Martí I Franqués s/n, 08028, Barcelona, Spain,
gratacos@geo.ub.es
Prediction of sedimentary facies and geometric architecture of sedimentary basin fills
through process-oriented numerical models is becoming an important and useful
tool in geological studies. Such information provides insight into spatial distribution
of physical, chemical and hydraulic properties within sedimentary deposits.
To date, various sedimentary modelling programs have been developed, most of
them considering either clastic material or carbonate sediments, but very few models
have attempted to consider interplaying, mixed carbonate-clastic sedimentation.
Moreover, most programs are designed in two dimensions in space, which is a major
restriction as geologic processes work in three dimensions creating a great variety of
sedimentary facies types distributed in a complex 3D architecture of sedimentary
bodies.
In this contribution, we present a 3D forward mathematical simulation
(SIMSAFADIM) that simulates clastic transport and sedimentation as well as
processes of carbonate production, transport and sedimentation in three dimensions.
We test the predictive capability of the model by simulating a marine transgression
during Langhian time in the Vallés-Penedés basin (Catalunya, NE Spain) with a
significant interplay between carbonate and terrigenous deposition.
- 25 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Stratigraphic Forward Modelling of deep marine systems using Sedsim
Griffiths, C.
CSIRO, Australia, cedric.griffiths@csiro.au
Sedsim has evolved to be able to model many of the features of submarine and
lacustrine gravity-flow deposits including sandy basin-floor fans, channel-levee
systems, ponded turbidites and debris flows. Examples are shown from modern and
ancient systems, together with explanations of the modelling assumptions.
- 26 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
The tectonic evolution of the northern North Sea from the Mid-Jurassic
form 2D subsidence analysis
Hanne, D.
University of Cambridge, Wiedhof 11, D-31249, Harber, Germany, dtlef.hanne@yahoo.com
Nine seismic lines have been investigated across the Viking Graben. From 2D
subsidence analysis, Pseudo-3D images of strain rate distributions in the Graben in
10 Ma intervals and estimates of the amounts of stretching have been developed. A
Mid-Jurassic and Late-Cretacous rift event (in the North of the Graben) were
identified.
- 27 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Fine-scale forward modelling - example from a Devonian reef of the
Canning Basin
Hasler, C.-A.¹ , Adams, E.W. 2, Wood, R.A.3, Dickson, J.A.D.
University of Cambridge, Downing Street, CB2 3 EQ, Cambridge, United Kingdom, chas02@esc.cam.ac.uk
MIT
3 Schlumberger Cambridge Research, Cambridge, United Kingdom
1
2
The spatial prediction of carbonate reef bodies within reservoirs - as well as that of
carbonate geometries in general - has proved difficult despite many years of research
by oil companies. Forward modelling at a fine scale may be a tool to better
understand and predict the internal discontinuities within the reef bodies. The
modelling is based on the data collected using a very accurate 3D differential GPS
tools on several outcrops from the Devonian reef of the Canning Basin (Western
Australia).
The modelling processes reconstitute the environmental conditions such as the
water-depth, the currents, the turbidity and the luminosity on the sea-floor in order
to predict the lateral distribution of the major protagonists of the Devonian Reef
Complex (stromatopororoids, stromatolites, tabulate corals, microbialites,
coarse/fine sediments, micrite?) The vertical evolution is constrained by the eustatic
evolution and by the ability of all the protagonists to grow and/or produce
sediments.
- 28 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Modelling turbidity currents by CFD simulations
Heimsund, S.1, 2, Hansen, E.W.M.3, Baas, J.H.4 & Nemec, W.1
1 Department
of Earth Sciences, University of Bergen, 5007 Bergen, Norway
snorre.heimsund@student.uib.no
3 Complex Flow Design AS, P.O. Box 1273, 7462 Trondheim, Norway
4 Department of Earth Sciences, University of Leeds, Leeds LS2 9JT, U.K.
2 E-mail:
In this study, laboratory-scale turbidity currents have been simulated by a numerical
approach known as computational fluid dynamics (CFD). Although relatively new in
the field of sedimentological research, this method is widely applied in hydraulic
engineering. CFD refers to the simplified numerical solution of the governing
equations describing fluid flow, namely the continuity, momentum and energy
equations. These are the mathematical formulations of the fundamental physical
principles of fluid dynamics: the mass and energy are conserved, and the Newton
second law is obeyed. For a viscous flow, they are known as the Navier-Stokes
equations. The commercial CFD software package called FLOW-3D has been used in
this study to perform numerical simulations of turbidity currents and to assess the
validity of this deterministic method. FLOW-3D subdivides the flow region into a
grid of variable-sized rectangular cells, with finite-difference (or finite-volume)
approximations used to compute (explicitly or implicitly) and monitor the spatial
and temporal changes of the basic flow values for each cell. The turbidity current is
simulated using a drift-flux technique, a two-phase model that describes the relative
flow of two miscible fluids with different densities. For viscosity evaluation
(turbulence closure) a renormalized group theory (RNG) model is used; employed
are also auxiliary models for gravity, pressure, density, shear stress, particle-fluid
interaction and the advection, erosion, settling and deposition of sediment. A 3-D
model has been constructed to imitate the laboratory ‘delta’ flume facility at the
Utrecht University. A number of numerical experiments have been performed,
focusing on the mean flow properties and flow structure of the whole current,
including also the effects of topography, erosion and deposition. The relative
sensitivity and importance of the individual flow parameters have been assessed
with respect to variation in the initial conditions and seafloor configuration. A
comparison of the numerical results with the Utrecht laboratory data shows their
good correspondence, which indicates that the CFD models give realistic results and
may be quite suitable for the simulation of turbidity currents.
- 29 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Forward Modelling & Prediction of Aeolian Systems Using Fuzzy Logic,
Constrained by Data from Recent and Ancient Analogues
Hern, C.1, Nordlund, U.2, Zwan, C.J. van der1 & Ladipo, K. 3
1 Shell
SEPTAR, P.O.Box 60, 2280AB Rijswijk, The Netherlands, caroline.hern@shell.com
se-74020 Vänge, Sweden
3 PDC, Port Harcourt Nigeria
2 Herrboda,
Aeolian reservoirs yield some of Shell‘s largest gas fields, such as NAM’s
Groningen field. Although, aeolian reservoirs have been studied for many years,
there is still room for improvement in the prediction of such reservoirs. With this
intention, a project was initiated to evaluate the factors influencing aeolian systems,
and deveolp a forward model using ‘fuzzy logic’.
The key aims were to:
 predict the type, amount and distribution of major facies types in aeolian
systems and,
 to compare resultant models with the regional-scale architecture
Fuzzy rules and sets, which define the behaviour of aeolian systems, were
constructed and used to modify the pre-existing fuzzy modelling software. The
modelling procedure was validated by using input data appropriate to the
Rotliegend climate and comparing the resulting models, in terms of thicknesses and
spatial distribution of facies types, to well data from the Upper Rotliegend interval of
the Lauwerzee Trough area, NE Netherlands.
- 30 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Using sub-regional scale forward models to condition reservoir-scale
stochastic scenarios
Hern, C., Lammers, H., Burgess, P. & Nijman, M.
Shell SEPTAR, P.O.Box 60, 2280AB Rijswijk, The Netherlands, caroline.hern@shell.com
Reservoir scale 3D static models are constructed based on available well and seismic
data, yet in many cases well data is sparse and seismic resolution is poor. This lack of
well or seismic control in the area of interest may result in an unconstrained and
unrealistic population of the 3D volume. In order to honour more truthfully the
geology, one approach may be to condition the reservoir scale model to a regional
scale numerical forward model.
Advances in predictive numerical forward modelling have enabled construction of
models constrained by available well data that reproduce and predict realistic
geological architectures at a number of scales. We show how a sub-regional scale
(37km long) forward model of the Grassy Member of the Blackhawk Formation
(Utah), constructed in Dionisos, was used to condition a reservoir scale hybrid
stochastic model. The forward model was clipped to extract a volume representative
of a small reservoir (3 x 2km). The gross distribution of facies associations indicated
in the forward model was used as a background in the stochastic model, into which
shale objects were distributed.
We compare the resultant hybrid model with detailed 3D models built and
conditioned to synthetic wells derived from the outcrop panels.
The methodology illustrates how the forward predictive capability of Dionisos
models at a sub regional scale, can be harnessed and utilised in conjunction with
reservoir modelling packages to fully describe facies scale variation at the reservoir
scale.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Investigation of gravitational mass transport processes - using the
Distinct Element Method as a modern tool in sediment transport
modelling
Huhn, K. & Kock, I.
Research Center Ocean Margins, University Bremen, Am Fallturm 1, D-28334, Bremen, Germany,
khuhn@uni-bremen.de
High-production regions, i.e. the NW African continental slope offshore
Mauritanian, are characterized by high sedimentation rates at the upper slope. These
materials are episodically transported down-slope in form of slides of intact layered
packages or by mixed and disordered debris flows and turbidites. The main purpose
of our studies is to investigate the influence of different key parameters for (a) slope
failure as well as (b) deformation and kinematic behaviour of gravitational mass flow
processes.
For our studies we use a numerical particle-based method - the Distinct Element
Method (DEM). This technique enables a wide range of material parameters and
model configurations. DEM simulations have been proved as an efficient tool to
quantify the influence of material parameters, i.e. basal as well as internal friction,
and geometrical settings for geodynamical processes like gravitational mass flows.
This method enables detailed information about mechanics and kinematics of downslope processes, mass transfer patterns, as well as internal and morphological
structures.
Nevertheless, we have to investigate the influence of model configurations and
assumptions in the face of transferability of model results into a natural system.
Thus, we develop a 2d DEM model which is built up of spherical, elastic frictional
particles. These spheres interact according to nonlinear-elastic Hertzian contact laws.
The total number of particles in each experiment is constant to simulate identical
sedimentation rates. First, we investigate the influence of deposition of sediments.
Therefore, in experiment (a) all spheres settle down under gravity in a triangular
shaped box on top of the upper slope. Removing the box boundaries releases a
gravitational mass flow. In experiment (b), all particles are settled under gravity on
top of a shelf surface and they are transported progressively by a bulldozer to the
upper slope. In both experiments, we change iteratively the basal friction on top of
the slope as well as internal friction of sediments. A decrease of basal friction as well
as of internal friction of sediments causes always an increase of run out length of the
flow while decreasing the thickness. In addition, an increase of internal friction of the
sediment causes evolution of a steeper upper slope in experiment (b) and an increase
in slope stability is observed. Thus, these experiment settings produce much more
natural conditions.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Modelling cycles of fluvial aggradation and degradation using a processbased alluvial stratigraphy model
Karssenberg, D.1, Bridge, J.S.2, Stouthamer, E.1, Kleinhans, M.G.1 & Berendsen,
H.J.A.1
1 The
Netherlands Centre for Geo-ecological Research (ICG), Faculty of Geographical Sciences, Utrecht
University, PO Box 80115, 3508 TC Utrecht, the Netherlands, d.karssenberg@geog.uu.nl
2 Department of Geological Sciences, Binghamton University, PO Box 6000, Binghamton, New York 139026000.
We have developed a prototype process-based alluvial stratigraphy model with
model run times representing time spans on the order of 103-105 years and a temporal
resolution of 1 year. The model represents a river valley and coastal plain with a
lateral spatial resolution on the order of 1-10 km2, defined by grid cells with a
constant size, and a vertical resolution of less than 10-2 m. Sediment is transported by
diffusional transport through a network of channels with a sediment flux boundary
condition at the upstream point of entry and a base level boundary condition at the
downstream edge of the model. Both boundary conditions can be varied in time.
Each channel has a channel belt with a width that increases in time at an
exponentially decreasing rate. The network of channels evolves as a result of channel
bifurcation and channel abandonment. The timing and location of channel
bifurcation is controlled stochastically as a function of the cross-valley slope of the
floodplain adjacent to the channel belt relative the down valley slope. Channel
abandonment, resulting in a bifurcation developing into an avulsion, occurs when
the discharge of one of the distributaries falls below a threshold value.
Floodplain aggradation occurs adjacent to actively aggrading channel-belts on
floodplain surfaces that do not exceed the elevation of the active channel belt.
Floodplain aggradation rate decreases exponentially with distance from the active
channel belt. Channel-belt degradation results in floodplain incision and transport of
eroded sediment from valley walls towards the incising channel belts. The erosion of
valley walls is calculated as a function of stream power for each location on the
valley wall. Compaction of channel-belt and floodplain deposits is modelled as a
function of depth of burial. Tectonic movement can also be simulated by faulting
and/or tilting of the floodplain in any direction.
The model is programmed in a standard spatio-temporal modelling language
that uses built-in functions and that allows easy addition of new model components.
The model can be run in Monte Carlo simulation mode, such that many model runs
are made to evaluate the effects of uncertainty in model input parameters. The model
is still being developed and tested against real-world data. However, examples are
given of the simulated effects of sea level change on rivers, such as: evolution of the
channel network; the upstream migration of knick points; formation of incised
channels and river terraces; and the effects of aggradation-degradation cycles on
patterns of avulsion and alluvial architecture.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Channelised turbidity currents: new insights into flow structure and
secondary circulation
Keevil, G.
School of Earth Sciences, Leeds University, LS2 9JT, Leeds, United Kingdom, g.keevil@earth.leeds.ac.uk
Sinuous submarine channels are major morphological features which act as conduits
for the transport of clastic sediment into the deep ocean. Such channels have long
been considered to be analogous to meandering fluvial channels. These comparisons
are commonly driven by similarities between the planform geometries of submarine
and fluvial channels.
Recent laboratory studies have revealed much about the velocity and density
structure of unconfined turbidity currents. The velocity structure and pattern of
secondary circulation (helical vortices with the long axis aligned parallel to flow)
within meandering fluvial channels is also well understood. However, prior to this
work, very little was known about the velocity and turbulence structure of
channelised turbidity currents.
Results from a series of new experiments will be presented where dense saline flows
were pumped into submerged meandering channel sections. Ultrasonic velocity
probes (UVP) provided high-resolution two dimensional flow fields. This has for the
first time allowed the quantification of the velocity profile of a channelised turbidity
current within a sinuous channel. Additionally these experiments have enabled the
visualisation and quantification of secondary cells within these channels. The results
clearly demonstrate a strong secondary flow cell which is strongest at the bend apex.
The basal component of the flow cell moves from the inside to the outside of the
bend, the reverse of what is expected within a fluvial channel. Such a finding has
great significance when assessing the validity of the comparison between
meandering fluvial channels, where the secondary flow cells influence the migration
and evolution of bends, and sinuous submarine channels. It implies that different
processes control the morphological evolution of sinuous submarine channels.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Predicting discharge and sediment flux of the Po River, Italy since the
LGM
Kettner, A.J. & Syvitski, J.P.M.
Environmental Computation and Imaging Group, Institute of Arctic and Alpine Research (INSTAAR),
University of Colorado, Boulder CO, 80309-0450, United States, Kettner@colorado.edu
INTRODUCTION
The EuroSTRATAFORM project aims at evaluating the influences of physical
characteristics of sediment sources and their temporal variability due to climatic
evolution and human impacts on continental-margin sediment flux. In the
framework of the project a number of rivers were chosen to simulate; among others,
the Po.
A numerical climate-driven hydrological model, HydroTrend, is applied to the
heavily anthropogenic influenced Po basin (drainage area 77,000 km2) in Northern
Italy to predict sediment fluxes and water discharge to the Adriatic Sea since the Last
Glacial Maximum (LGM).
MODEL CONCEPTS OF HYDROTREND
To simulate discharge and sediment discharge fluxes, HydroTrend incorporates
drainage basin properties (river networks, hypsometry, relief, reservoirs) based on
high-resolution digital elevation models (for example HYDRO1k DEM), along with
other biophysical parameters (basin-wide temperature, precipitation, evapotranspiration, canopy, soil depth, hydraulic conductivity, glacier characteristics). A
stochastic model (Morehead et al., 2003) is used to calculate the daily suspended
sediment load fluxes:
 Qs 
Q
     
Q
 Qs 
C
(1)
Wherein Qs is the daily suspended sediment discharge (kg/s), Q the daily discharge
(m3/s), Q s the long-term average of Qs, Q the long-term average of Q,  a lognormal random variable and c a normal random variable.
The long-term average of Qs is defined as:
Qs   3 A R e k T
4
(2)
5
Wherein A is the drainage basin area (km2), R the maximum relief (m), T the basinaverage temperature (C), 3, 4, 5 and k dimensionless coefficients which depend
on climatic zone based on the geographical location of the drainage basins (Syvitski
et al., in press b). studying the case of the Po river, climate changes from Last Glacial
Maximum (LGM) until the present do not reach the threshold values to affect
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
changes in ’s or k. The Long-term average suspended sediment will only be affected
by changes in A, R and T .
The daily bedload Qb (kg/s) is simulated using a modified Bagnold (1966)
equation:
  s  gQ  seb

Qb  



 s
 g tan f
when
u  ucr
(3)
Where s is sand density (kg/m3),  is fluid density (kg/m3), Q is the daily discharge
(m3/s), s is the slope of the riverbed (), eb is the bedload efficiency,  is a
dimensionless bedload rating term, f is the limiting angle of repose of sediment
grains lying on the river bed (), u is stream velocity (m/s), and ucr is the critical
velocity (m/s) needed to initiate bedload transport.
The model with documentation, example files and references is available on the
web: http://instaar.colorado.edu/deltaforce/models/hydrotrend.html.
CALIBRATION TEST, PRESENT DATA VERSUS MODELED
Present-day climate statistics including monthly mean temperature and
precipitation and their standard deviations of the Po drainage basin are retrieved
from daily data records (1977 - 1991) of 20 climate stations weighted in terms of
influence by elevation. The yearly mean temperature, precipitation and their
standard deviations also weighted in terms of influence by elevation are obtained
from monthly data records (1760 – 1995) of 13 climate stations from the Global
Historical Climatology Network of National Oceanic and Atmospheric
Administration, (NOAA) (Vose et al., 1997)
(http://ingrid.ldeo.columbia.edu/SOURCES/.NOAA/.NCDC/.GHCN/).
HydroTrend verifies as an appropriate simulation model for the gauging station
closest to the river mouth before being split into distributary channels. At this delta
apex there is a high correlation between modeled discharges and time series of daily
discharge data (1990-2001) and monthly discharge (1918-present). HydroTrend also
generates similar discharge variability as compared to the 12-year daily measured
discharges (fig. 1). Modeled data correlates significantly with the observed data (r2 of
0.72), as calculated from 100m3/s intervals.
Figure 2 indicates that the monthly mean discharges are underpredicted during
the winter months (November till March) and overpredicted during the summer
(April till September). This deviation relates to the well known 'reservoir' effect
common in river basins containing major reservoir lakes (Bobrovitskaya, 1996), and
the discharge controlled management for hydro-power. Over a third of the discharge
of the Po river discharge is affected by the hydro-power reservoirs (Camusso et al.,
2001).
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
measured
2500
1552
1532
1712
1500
741
1000
534
Number of events
2000
1912
modeled
0
2
11
00
0
3
3
90
00
-
10
00
0-
90
00
80
00
-
70
00
-8 0
00
60
00
-7 0
00
50
00
-6 0
00
40
00
-5 0
00
30
00
-4 0
00
20
00
-3 0
00
10
00
-2 0
00
0- 1
00
0
0
10
00
0
2
1
15
4
34
17
39
27
69
69
237
253
500
3
Discharge ranges (m /s)
Fig. 1 Discharge distribution of12yr daily mean measured versus modeled discharge.
Measured
Modeled
3500
3000
Q (m3/s)
2500
2000
1500
1000
500
De
cem
be
r
No
vem
be
r
be
r
Oc
to
be
r
Se
pte
m
Au
gu
st
Ju
ly
Ju
ne
Ma
y
Ap
ril
Ma
rc h
Fe
br u
ar y
Ja
nu
a ry
0
Time (Months)
Fig. 2 Monthly mean discharge distribution based on 100yr monthly measured versus
modeled data. The dashed lines indicate mean discharge values plus or minus their
standard deviation. The arrows show the huge impact the reservoirs have on the
monthly mean discharge distribution.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
The Po’s discharge is strongly affected by its 5 large reservoirs, sediment fluxes
will likely be influenced even more. HydroTrend to some extent can be adjusted to
incorporate reservoir effects on sedimentation.
The model simulates trapping efficiency TE depending on the reservoir volume
either by the Brown equation, for reservoirs smaller or equal than 0.5 km3, or the
modified Brune equation by Vörösmarty (1997), for reservoirs larger than 0.5km3
(formula 4 and 5).
TE  1 
0.05

(4)
Wherein Δτ is the approximated residence time and is estimated by:
ni
 
V
i
(5)
1
Qj
Where Vi is operational volume of the reservoir i, Q is the discharge at mouth of each
regulated subbasin j. Simulations show a TE of 20.4% of suspended sediment load for
the entire Po drainage basin.
At the delta apex, HydroTrend predicts an average discharge of 1,542 m3 s-1 and
peak discharges comparable to the measured floods of 1951 and October 2000. Based
on the formulas 1, 2 and 3, average suspended sediment load of 16 x 106 t yr-1 with
peak years of 39 x 106 t yr-1 are predicted. Bedload contributes only ~2.5% of the total
sediment output of the Po river system (table 1). There is a good correlation between
bedload transport and high suspended sediment concentrations, figure 4.
Table 1.
Characteristics of the Po River, measured values against a 100yr simulation.
Measured at Modeled
apex (Pontelagoscuro)
Long-term average discharge (m3 s-1) a
1,500
1,542
3
-1
Last century floods (m s )
10,300
10,281
9,600
10,110
8,700
9,779
Average suspended sediment load (t 15 x 106
16 x 106
-1
b
yr )
Peak suspended sediment load (t yr-1) c 35 x 106
39 x 106
Average bedload (t yr-1)
--4.0 x 105
Sediment yield (t km-2 yr-1) b
201
207
a) Nelson, 1970
b) Cattaneo et al., 2003
c) Friend et al., 2002
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
4.5
4
ln Qb (kg/s)
3.5
3
2.5
2
1.5
1
0
2
4
6
8
10
12
14
ln Qs (kg/s)
Fig 4. 100yr daily simulation of the Po, suspended sediment discharge (Qs) against bedload
(Qb).
LGM VERSUS PRESENT SIMULATIONS
Adriatic sea level was about 120 meter below present during the LGM (Fairbanks,
1989). An estimate of the Po basin area during LGM was made based on present-day
DEM and bathymetry data (Sandwell and Smith, 1999). The shoreline was about
350km SE of the present-day Po outlet, because of the shape of the relatively shallow
Adriatic Sea. This implies that part of the Apennine rivers, for example the Metauro,
Potenza and the Chienti, as well as present-day Northern Italian and Croatian rivers
were contributaries to the Po basin which eventually drained into the modern
foredeep basin of the Apennine chain. This shift in the coastline position increased
the total area of the Po drainage basin by approximately a factor of 1.9 compared to
its present estimated area (fig 5). The Alps were almost completely covered by the
late-Würmian ice-sheet, but the ice cap did not add significant area to the Po basin as
the glacier drainage divide roughly followed the basin divide (Baroni, 1996). For this
100 year LGM study we assume no changes in the late-Würmian ice-sheet area.
The monthly climate statistics since the LGM, 21kyBP, are retrieved from the
Community Climate Model1 (CCM1) (Kutzbach et al., 1998). Using the model is
justified by Peyron et al. (1998) who pointed out that the cool steppe vegetations is
coherent with simulations performed using the CCM1 model during the LGM.
According to the model, mean annual temperature is 3 times lower (11.5°C vs. 3.5°C)
and precipitation increases by 25%. A 100 year HydroTrend simulation indicate that
the average discharge increases with a factor two, to 3045 m3 s-1.
Bedload is closely related to the discharge (see formula 3) inducing an increase;
present bedload of 4.0 x 105 t yr-1 versus 8.2 x 105 t yr-1 during the LGM (see fig. 6).
The discharge distribution is more fluctuating during the LGM even though under
- 39 -
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
modern climate the larger area would bring about less fluctuating discharge. The
increase in bedload implies coarser total sediment flux during LGM compared to
present sediment fluxes.
Fig 5. Po drainage basin area at present (black, 77,000km2 with a river length of 670km),
versus hypothetical drainage basin area at LGM (gray, 148,900km2 with a river
length of 1250km).
There appears to be no to little change in the average suspended sediment load
(16.1 x 106 t yr-1 nowadays against 16.2 x 106 t yr-1 during LGM) though suspended
sediment fluxes appear to be less fluctuating during LGM compared to present
simulations (fig. 7). This is remarkable, because the nowadays decoupled small
Apennine rivers (Metauro, Potenza and the Chienti) have sediment yields of ~1,400 t
km-2 yr-1 and go hyperpycnal every 2 to 4 year.
Qbedload present
Q Present
Qbedload LGM
Q LGM
120
9.0E+05
110
8.0E+05
100
7.0E+05
90
6.0E+05
80
5.0E+05
70
4.0E+05
60
3.0E+05
50
2.0E+05
40
1.0E+05
30
0.0E+00
20
1
11
21
31
41
51
61
Number of modeled years
- 40 -
71
81
91
Q (km3 /yr)
Qb (t/yr)
1.0E+06
Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Fig. 6. Bedload – discharge comparison between present s and LGM simulation.
Present conditions
LGM conditions
4.50E+07
4.00E+07
3.50E+07
Qs (t/yr)
3.00E+07
2.50E+07
2.00E+07
1.50E+07
1.00E+07
5.00E+06
0.00E+00
0
10
20
30
40
50
60
70
80
90
Number of modeled years
Fig. 7. A comparison between present yearly suspended sediment discharge versus LGM
suspended sediment discharge.
These simulations indicate a dynamic system under strongly changing boundary
conditions. HydroTrend provides a method to quantify the effects of these dynamic
boundary conditions and as such will generate input estimates for other modeling
efforts. Future study on Po sediment fluxes will focus on a time continuous
simulation since LGM.
REFERENCES
Asioli, A., Trincardi, F., Lowe, J.J., Ariztegui, D., Langone, L. and F. Oldfield, 2001. Sub-millennial
scale climatic oscillations in the central Adriatic during the Lateglacial: palaeoceanographic
implications. Quaternary Science Reviews 20, 1201-1221.
Bagnold, R.A., 1966. An approach to the sediment transport problem from general physics; U.S.
Geological Survey Professional Paper 422 (1), 1-37.
Baroni, C.,1996. The Alpine “Iceman” and Holocene Climatic Change. Quaternary Research 46, 78-83.
Bobrovitskaya, N.N., Zubkova, C. and R.H. Meade, 1996. Discharges and yields of suspended
sediment in the Ob' and Yenisy Rivers of Siberia. In: Walling, D.E. and B.W. Webb (eds) Erosion
and Sediment Yield: Global and Regional Perspectives. Intern. Association of Hydrological
Sciences Publ. no. 236, 1996.
Camusso, M., Balestrini, R. and A. Binelli, 2001. Use of zebra mussel (Dreissena polymorpha) to assess
trace metal contamination in the largest Italian subalpine lakes. Chemosphere 44, 263-270.
Cattaneo, A., Correggiari, A., Langone, L and F. Trincardi, 2003. The late-Holocene Gargano
subaqueous delta, Adriatic shelf: Sediment pathways and supply fluctuations. Marine Geology
193, 61-91.
Fairbanks, R.G., 1989. A 17,000 year glacio-eustatic sea level record: Influence of glacial melting rates
on the Younger Dryas event and deep-ocean circulation. Nature 342, 637-642.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Friend, P.L., Amos, C.L., Panin, N. and F. Trincardi, 2002. Sediment supply and river discharge to the
continental shelf – A synthesis of existing data for the Ebro, Rhone, Po and Danube river systems.
Abstract of Joint European/North American EUROSTRATAFORM meeting, incorporating
EURODELTA and PROMESS, September 2002.
Kutzbach, J., Gallimore, R., Harrison, S., Behling, P., Selin, R., and F. Laarif, 1998. Climate and biome
simulations for the past 21,000 years Quaternary Science Reviews 17, 473-506.
Morehead, M.D., Syvitski, J.P., Hutton, E.W.H. and S.D. Peckham, in press 2003. Modeling the
temporal variability in the flux of sediment from ungauged river basins. Global and planetary
change 815, 1-17.
Nelson, W.N., 1970. Hydrography, sediment dispersal, and recent historical development of the Po
river delta, Italy. In: Morgan, J.P. (eds) Deltaic Sedimentation; Modern and Ancient Society of
Economic Paleontologists and Mineralogists. Special Publication No. 15, November 1970. Tulsa,
Oklahoma, USA.
Peyron, A., Guiot, J., Cheddadi, R., Tarasov, P., Reille, M., Beaulieu, J.L. de, Bottema, S. and V.
Andrieu, 1998. Clomatic Reconstruction in Europe for 18,000 YR B.P. from Pollen Data,
Quaternary research 49, 183-196.
Sandwell, D.T. and W.H.F. Smith, 1999. Bathymetric estimation. In: Satellite Altimetry and Earth
Sciences, Academic Press, 1999.
Syvitski, J.P.M., Kettner, A.J. and S.D. Peckham in press a. Predicting the Flux of Sediment to the
Coastal zone: Application to the Lanyang watershed, northern Taiwan. Journal of Coastal Reserach.
Syvitski, J.P.M., Peckham, S.D., Hilberman, R.D. and T. Mulder in press b. Predicting the terrestrial flux
of sediment to the global ocean: A planetary perspective. Marine Geology.
Vose, R.S., Schmoyer, R.L., Steurer, P.M., Peterson, T.C., Heim, R., Karl, T.R. and J. Eischeid, 1992. The
Global Historical climatology Network: long-term monthly temperature, precipitation, sea level
pressure, and station pressure data. ORNL/CDIAC-53, NDP-041. Carbon Dioxide Information
Analysis Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee.
Vörösmarty, C.J., Meybeck, M., Fekete, B. and Sharma, K., 1997. The potential impact of neoCastorization on sediment transport by the global network of rivers. Human Impact on Erosion and
Sedimentation. IAHS Publication no. 245, 1997.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Modelling bedding and petrophysical characteristics of tidal heterolithic
reservoirs using a process-oriented approach
Martinius, A.W.
Statoil R&D,Arkitekt Ebbelsvei 10, Rotvoll, N-7005, Trondheim, Norway, awma@statoil.com
This poster will present the results of five-year R&D programme to model the true
3D spatial architecture and petrophysical properties of tidal deltaic heterolithic
deposits. Early work focssed on correct implementation of sedimentological
processes, including empirical results from flume tank experiments, in a
mathematical framework representing bi-directional deposition and erosion of a
heterolithic sand-mud system in a tidal deltaic environment. The modelling tool,
SBEDTM, has been successfully used to estimate effective flow properties via
calibration of models against observed sub-surface well data. As well as giving a
valuable insights into the nature of sedimentological processes (e.g. bedding
architecture and bedding cyclicity) the modelling method has helped us to unravel
the nature of flow properties in these heterolithic systems. This has resulted in an
effective permeability prediction function incorporating effective flow and
percolation theory.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Tectonic control on past circulation of the Mediterranean Sea
Meijer, P.1, Slingerland, R.2 & Wortel,R.1
1 Faculty
of Geosciences, Utrecht University, Budapestlaan 4, 3584 CD, The Netherlands, meijer@geo.uu.nl
of Geosciences, Penn State University, USA
2Department
We examine the effect of Late Miocene paleogeography on the circulation and water
properties of the Mediterranean Sea by using an ocean general circulation model.
Results obtained for the past are compared to a control experiment with the presentday geometry. To focus on paleogeography, atmospheric forcing is always based on
the present-day climatology. We seek insight that allows us to test ideas based on
observations and to formulate new working hypotheses. The Late Miocene
represents an important stage in the evolution of the Mediterranean. The present-day
model reproduces the main aspects of the surface to intermediate depth circulation
and water properties. The model does not capture the deep circulation known to
occur at present in both subbasins. When the subbasins are reconstructed to their
Late Miocene shape (keeping intervening sills at present-day levels) the overall
nature of the surface/intermediate depth circulation proves unaffected. The model,
however, predicts intense deep circulation in the eastern Mediterranean – most likely
due to the greater surface area of the reconstructed Adriatic Sea. Using the first
paleoexperiment as a starting point several additional paleogeographical aspects are
examined.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Numerical Modeling of the Sedimentary Systems of Large-scale Coastal
System Tracts
Niedoroda, A.W., Reed, C.W.1, Das, H.1, Donoghue, J.2, Ferraghazzi, S.2 , Wang,
Z.B.3 & Stive, M.4
URS Corp., 3676 Hartsfield Road, Tallahassee, FL, 32303. USA. alan_niedoroda@urscorp.com
Geology Department, Florida State University, Tallahassee, FL, 32306. USA Jdonoghu@mailer.fsu.edi
3 Marine and Coastal Management, WL/Delft Hydraulics, 2600 MH Delft. The Netherlands.
Zheng.Wang@wldelft.nl
4 Delft University of Technology, Stevinweg 1, Room 3.69, 2600 GA Delft. The Netherlands.
M.J.F.Stive@ct.tudelft.nl
1
2
The Coastal System Tract concept (Cowell et al., in press) expresses the importance of
sediment-sharing processes between a variety of individual system elements in a
given coastal region. The surf zone/beach system, the shoreface/shelf system and
the inlet/estuary system are all examples of the individual system elements. There
are many others examples dictated by the scale and nature of the specific problem
undergoing analyses.
The CST-Model has been developed to provide a quantitative tool that represents the
complex interactions between arbituary combinations of the sediment-sharing
elements. This is a large-scale behavior-oriented 2-DH model, based on representations of the physics of the macroscopic morphodynamic processes. The model
operates on an inter-annual time scale so that it can resolve trends in system-wide
morphology over periods of decades to millennia. It is capable of resolving various
combinations of river sources, estuaries and lagoons, flood- and ebb-tide shoal
complexes, and inlets in concert with a littoral surf zone, shoreface, continental shelf
and upper continental slope. The shoreline translates according to the dictates of
sediment transport gradients. Although the individual components are portrayed in
different numerical schemes they are linked by a common time-step so that the nonlinear aspects of system integration are preserved.
The CST-Model has been used to examine several different examples of coastal
system tracts. In one case, the effects of millennial-scale Dansgaard-Oeschger late
Quaternary climate and sea level cycles with amplitudes on the order of 0.5 m were
examined using a system that contains a river, estuary, inlet, barrier island, shoreface
and shelf complex. The system of clinoform development and coastal progradation
predicted in the model are similar to those observed on the central Florida Panhandle
coast. In another case, the development of a Holocene subaqueous shelf clinoform
along the central Italian Adriatic coast was modeled. A number of different source
and forcing parameter patterns were varied to demonstrate features that can be
identified in the internal stratigraphy of the deposits. These compared favorably
with patterns identified in the sub-bottom records.
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The CST-Model examples illustrate how large-scale processes can either be diagnosed with modeling techniques or simulated in order to make predictions. This
model is publicly available to the research community.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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3-D Photorealistic models of geologic outcrops, a tool to collect quantitative data; methodology and histories examples in Utah and Wyoming
Olariu, C.
University of Texas at Dallas, 2601 North Floyd Road, 75080, Richardson, TX, United States,
cornelo@utdallas.edu
The study of outcrops remains a primary tool for understanding facies architecture,
build conceptional model and for reservoir characterization studies. Despite the
desire of geologists to study continuous, large outcrops, these are difficult to
accurately quantify by conventional methods and cliff faces can be tens to hundreds
of meters high and/ or kilometres long.
Using digital cameras, fast laser rangefinders and GPS, 3-D photorealistic
models of the outcrops can be built by:
1. scanning the terrain surfaces of the outcrops;
2. positioning a modest number of photo-control points;
3. digital image collection;
4. building terrain surfaces of the outcrops on the computer;
5. transferring image-coordinates into global coordinates;
6. transforming images on to terrain surfaces.
Photorealistic models of the outcrop can be interpreted on a computer. The
accuracy of the terrain surface is dependent on the laser used but can as good as
millimeters. Also, sedimentary structures observed on the outcrop model depend on
a combination of terrain detail and image resolution. Knowing the real 3-D positions
of bed contacts on the photorealistic model of the outcrop, a continuous quantitative
data such as bed thickness or inclination can be extracted. If the outcrop has a curved
geometry or the same bed contact crop on the sides of a canyon, 3-D surfaces might
be built by curve fitting and ultimately a solid volume model.
The possibility of extracting continuous quantitative data from the outcrops supports
the numerical modeling development of the deposits.
Examples presented will be from delta front deposits of the Cretaceous
Panther Tongue, Utah, and the Wall Creek, Wyoming. Panther Tongue deposits were
interpreted using 3-D photorealistic methods together with ground penetrating radar
(GPR).
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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Upscaling the time parameter in stratigraphic simulation models:
efficient use of high-magnitude low-frequency events
Overeem, I.1 & Storms, J.2
University of Colorado, Institute of arctic and alpine research, Campusbox 450, 80309-0450, Boulder, CO,
United States, irina.overeem@colorado.edu
2 Delft University of Technology, Department of applied Earth Sciences, Mijnbouwstraat 120, 2628 RX Delft,
The Netherlands, j.e.a.storms@citg.tudelft.nl
1
When developing a stratigraphic simulation model, much time and effort is generally
put into upscaling sediment transport processes, rather than time. But even with
present-day computing power, it is extremely difficult to simulate detailed (high
time resolution) sedimentary development over long, geological periods of time. The
efficiency of sediment transport processes is not constant in time but changes with
the variable amount of energy which is available to the depositional system by
means of e.g. water discharge (fluvial-deltaic system) or wave magnitude (coastal
system). To speak with Derek Ager's (1980) words geologic history can be
characterized as "long periods of boredom and brief periods of terror". We here
present an upscaling approach that incorporates the high-magnitude low-frequency
events that appear to be the important building blocks in stratigraphy, without
loosing calculation efficiency in our models. This event-based approach has
successfully been applied in two process-response models: SedFlux and BarSim.
SedFlux is a coupled simulation model that simulates shelf architecture by including
among others the following processes: bedload spreading, dispersal of a delta plume
through either hypopycnal or hyperpycnal plumes, reworking of sea-floor sediment
by storms and failure and subsequent transport as sediment gravity flows (turbidity
currents or debris flows). All these processes are driven by discharge and sediment
input. We select the river flood events that carry 90 % of the sediment from a record
that has daily values, and only simulate those days in detail. The model averages
over the intermittent days and deposition takes place as one single fair-weather
layer. Depending on the erraticness of the river system under study this will save
often
an
order
of
magnitude
in
calculation
time.
BarSim models evolution and stratigraphy of wave-dominated coastal systems. The
model uses variable time-steps to simulate individual storm events and fair-weather
periods. During storms net sediment transport is in offshore direction, whereas fairweather moves sediment back onshore. In addition, sediment supply from for
example suspension or littoral drift only occurs during fair weather. Storm wave
heights and recurrence interval are drawn from cumulative probability distributions
to determine storm conditions and duration of the subsequent fair weather.
We find that the event-based approach as compared to the traditional time-averaged
approach has distinct influence on the modeled geometry and grain-size
distributions. The longitudinal profiles, resulting from either model, show increased
deposition distally. The river peak events in SedFlux shoot out delta plumes further
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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offshore and high-magnitude events in BarSim are able to erode the shoreface and
transport sediment beyond the wavebase, out of reach of the normal fair-weather
processes.
Simulated event beds can be interpreted in terms of reworking ratio, grain-size
variability, and granulometric facies and can almost directly be compared to real
event strata. Also, coupled processes that are threshold controlled are averaged out
under time-averaged conditions. (e.g. turbidity current due to hyperpycnal plumes
in SedFlux were absent under time-averaged conditions). To conclude, upscaling the
time parameter to separate between events and non-events opens new options to
better understand both small-scale stratigraphic and large-scale geometric variability.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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Analogue modelling as a tool for investigating causality in alluvial
stratigraphy
George Postma
Utrecht University, Faculty of Geosciences, Budapestlaan 4, 3584 CD Utrecht, The Netherlands,,
gpostma@geo.uu.nl
Analogue flume models that are properly scaled toward real world prototype riverdelta systems proof suitable to put constraints on existing models when and why
rivers of any substantive size will or will not aggrade and preserve systems tracts
and their bounding surfaces along their course. Flume modelling done so far have
been proven to be adequate in ascribing variation in architectural style to rates of sealevel change (e.g. Van Heijst & Postma, 2001), to subsidence rates in growth fault
settings (Van Heijst et al. 2002), and to rates of climate change (Van den Berg van
Saparoea & Postma, 2003). Analogue flume modelling proved suitable for systematic
exploration of sedimentary system’s sensitivity to allocyclic change. After a brief
review the presentation shows the outcome of the first experiments on autocyclic
behaviour of alluvial system in the new flume facility Eurotank at Utrecht
University.
Review
The most important architectural styles and sequence stratigraphical models of
fluvial systems are briefly reviewed. The large-scale architecture in fluvial-deltaicshelf settings (5th order bounding surface and higher) is defined by the amount of
sediment transport that is induced by the rate of sea level change and the ratio of
discharge (climate signal) and available bed load (the latter depending on
denudation rate and temporarily-stored sediment). Since the amplitudinal variation
in sea-level change is much different for fourth order sea-level changes during
greenhouse and icehouse periods we think that the present is not the key to the past
for understanding fluvial architecture and that present sequence stratigraphical
models need to accommodate for these differences.
Autocyclic behaviour
The first experiments that have been obtained from Eurotank focus on the autocyclic
behaviour of the alluvial system. With the term autocyclic is meant the development
of an the alluvial system without change in the total energy and material input into a
sedimentary system.
Keeping all input variables constant, the development of the alluvial system
between valley outlet and shelf margin follows a three-phase development. In the
first phase, water jets out of the valley causing a cone-shaped, channel-levee
depositional feature on the flat coastal plain. During the second phase, water is
spreading radially over the forming cone reshaping it into a radial-braiding alluvial
fan system. The aggradation rate is high at this stage. In the third phase individual
channels start to form at the toes of the fan. These channels develop down to the
shoreline, while the water flow is still unconfined. Importantly, it is observed that the
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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carrying capacity of the water flow is much reduced after passing the fan toe. After a
while, a multiple channel network start to form by avulsion at the fan apex
producing multiple point sources at the shelf margin. The three phase development
is similar to that found by Van Wagoner et al. 2003 and Dunn et al. 2003.
Discussion
Although a systematic experimental data base is still lacking at time of presentation,
it is clear that the radius of the braided system is increasingly smaller for lower
discharges. Also the time period needed to come to channel formation is shorter for
lower discharges. The observed transition from a radial braided system to a channel
belt system is marked by a slope break being at the boundary of a strongly
depositional landscape producing sheet sandstones and a slightly depositional to
erosive landscape with distinct channel belts. Blair & McPherson (1994) noted a
similar gradient difference of modern alluvial fans and rivers. The three stage
evolution of alluvial systems is also seen in the evolution of a crevasse (Smith et al.
1989; Pérez_Arlucea & Smith, 1999, Farrell, 2001) showing similar development from
sand sheet to channels. Murray and Paola (1994) called a braided system a
fundamental landform, where the only factors essential for braiding are bed load
sediment transport and laterally unconstrained free-surface flow. However, our
experiments show that where the channel belts come into existence the flow is still
unconfined. In our opinion, the carrying capacity, governed by the discharge per unit
area seems much more important than the confinement of the flow. Preliminary data
from analogue experiments shows, indeed, that the position of the break between
these two fundamental landforms depends on discharge and thus will shift back and
forth with climate change.
Further research shall contribute to establishment of boundary conditions where
fundamental landforms shall exist. These conditions are to be estimated from
physical modelling and to be verified along natural examples.
References
Blair & McPherson (1994) J. Sediment Research 64, 450-489.
Dunn et al. (2003) AAPG/SEPM Abstracts
Farrel, K.M. (2001) Sedimentary Geology 139, 93-150.
Murray and Paola (1994) Nature, 371, 54-57
Pérez_Arlucea & Smith (1999) J. Sediment Research, 69, 62-73.
Smith et al. (1989) Sedimentology, 36, 1-23
Van Wagoner et al. (2003), Abstract AAPG/SEPM 2003, Salt Lake City
Van den Berg van Saparoea & Postma (2003) Abstract AGU-EUG Mtg. 2003 Nice.
Van Heijst & Postma (2001) Basin Research, 13, 269-292.
Van Heijst et al. (2002) AAPG Bull, 46, 1335-1366.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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2D Subsidence Modelling of Middle Triassic Carbonate Platform
Development in the Lombardian Alps (Italy)
Seeling, M.
University of Heidelberg, Institute of Geology and Paleontology, Im Neuenheimer Feld 234, D-69120,
Heidelberg, Germany, Michael.seeling@urz.uni-heidelberg.de
An Upper Permian to Upper Triassic succession with a thickness of more than 2000
m is well exposed in the Camonica Valley of the Lombardian Alps (Italy). The clastic
and carbonate sediments were formed on a passive continental margin, which was
occasionally influenced by strong regional transtension. Several carbonate build-ups
developed in the Middle Triassic, e.g. the Pora platform and the Concarena platform
(Esino Fm.) in the late Ladinian. The rimmed Pora platform has a thickness of up to
400 m, a lateral extension of approximately 10 km and shows strong progradation of
megabreccia clinoforms. It covers a time interval between the Archelaus zone and the
Ladinian/Carnian boundary (top of Regoledanus zone). The Concarena platform
includes a succession of approximately 1500 m thickness. It measures only 4 km in
diameter and shows less Progradation than the Pora platform. All typical facies belts
of a carbonate platform are present. Large parts of the reef crest still exist and
flattening out clinoforms flank this isolated platform. Parts of the existing lagoon
consist of hundreds of shallowing upward meter-scale cycles.
Detailed basin analysis with reverse modelling shows a complex pattern of
differential subsidence between the two platforms in the Camonica Valley. The
platform geometries were controlled by an asynchronous development of
accommodation space at the beginning of platform growth, induced by tectonic and
volcanic activity in Ladinian time. Decompaction calculations of the Ladinian
sediments and stratigraphic/geometric restoration of overlying Carnian succession
shows a subordinate influence of compaction-induced subsidence on development of
accommodation space. Total subsidence rates for the Pora platform are between 80
m/Ma (platform core) and 170 m/Ma (basin) and were strongly outpaced by
sedimentation rates. At the end of the Longobardian, the basin had been completely
filled and the initial bathymetry between platform and adjacent basin was nearly
levelled. Karst features (Calcare Rosso) on top of the entire platform indicate
subaerial exposure at the end of platform growth, induced by a global sea-level fall.
Calculations of total subsidence rates for the Concarena platform yield values
between 320 m/Ma and 360 m/Ma. Sedimentation rates were higher than subsidence
rates, but the basin could not bee filled: on the end of platform growth the basin still
existed and fine-grained, still water carbonates were accumulated.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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The Community Surface-Dynamics Modeling System: An Environment
for Developing, Sharing, and Using Sediment Models
Slingerland, R.
Department of Geosciences, The Pennsylvania State University, 16802, University Park, PA, United States,
sling@geosc.psu.edu
On behalf of sedimentary geologists worldwide, the US National Science Foundation
in collaboration with other science-funding agencies is poised to establish an
initiative called the Community Surface-Dynamics Modeling System (CSDMS).
CSDMS is a modeling environment containing a community-built and freely
available suite of integrated, ever-improving software modules predicting the
transport and accumulation of sediment and solutes in landscapes and sedimentary
basins over a broad range of time and space scales. The scientific infrastructure for
CSDMS will be coordinated and funded by government agencies and industry and
structured to allow sedimentary modelers from the geological, oceanographic, and
engineering communities to determine the optimum algorithms, input parameters,
feedback loops, and observations to better predict sedimentary processes and their
products. The system is being designed to address both basic science and applied
problems such as improved assessment of risk from natural hazards, improved
predictive capability of stratal architecture, an understanding of the manner in which
sedimentary basins and erosional landscapes participate in biogeochemical cycles,
and better interpretation of the record of global and regional climate change.
The modeling system consists of three major components coordinated by a system
supervisor in the form of GUI, which provides an interactive environment for user
access. The Standard Utilities component maintains and stores all data and variable
arrays in a compact and quickly retrievable format and contains the Module
Connector, an application that allows users to easily link together process-modules
from the module library to build a model, thus providing graphical, icon-based
model construction. The Module component contains a variety of communitysupplied, compatible computer programs simulating sedimentary processes. Several
modules for a given process may be present, each representing an alternative
conceptualization or approach to simulating that process. Conceptualizations in a
module may be of the traditional PDE form, cellular, or rule-based. The Toolkit
Component contains the basic information technology for generating grids and
solving equation sets, such as high-order PDE and hybrid PDE/cellular solvers,
adaptive meshes, automated mesh and algorithm selection, time-stepping, and
domain coupling procedures. Automatic code generators will construct spatial
simulations and enable distributed processing over a network of parallel and serial
computers, allowing the user transparent access to a network of computing facilities.
Nothing approaching the CSDM project in scope or level of cross-disciplinary
integration has ever been attempted in the sedimentary geology and surface
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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processes communities, but some examples of current multi-system modeling will be
presented to illustrate its potential.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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Avulsion, autogenic or allogenic controlled?
Stouthamer, E. & Berendsen, H.J.A.
The Netherlands Centre for Geo-Ecological Research (ICG), Department of Physical Geography, Faculty of
Geographical Sciences, Utrecht University, E.Stouthamer@geog.uu.nl
Because avulsion is an intrabasinal process it is generally considered to be autogenic.
However, the avulsion process is not only controlled by autogenic but also by
allogenic processes.
The Rhine-Meuse delta is without doubt the most extensively studied delta
regarding avulsion processes on the timescale of the Holocene. Data suggesting an
autogenic nature for the timing of avulsions are:
 the interavulsion period in the Rhine-Meuse delta on average appears to be
constant (~ 945 cal yr);
 the natural levees of all avulsed channels have a constant elevation relative to
groundwater levels, suggesting that the critical superelevation for avulsion
remains constant through time;
 a weak 500 14C yr cycle seems to be present in the avulsion frequency.
However, the avulsion locations are not randomly distributed over the delta.
Avulsion locations are related to allogenic factors, interacting over time and space.
Eustatic sea level rise and glacio-hydro-isostacy played a dominant role from 75004500 14C yr BP, (local) tectonics from 4500-2800 14C yr BP and discharge/sediment
load changes from 2800-1000 14C yr BP. After 1000 14C yr BP avulsions are controlled
by humans.
In conclusion, it seems that avulsion is controlled by both autogenic and allogenic
processes. The relative importance of these processes varies over time and space and
leads to different alluvial architectures.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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Variation in dip of lateral accretion surfaces in subrecent fluvial deposits,
Pannonian Basin, Hungary: a reflection of climatic fluctuations or just
meandering excursions?
Sztanó, O. 1 & Mészáros F. 2
1 Department
2
of Geology, Eötvös University, H-1117, Budapest, Pázmány P. sétány 1/C, sztano@ludens.elte.hu
The Relief Laboratory, H-8442. Hárskút, P.O.Box 1, ferenc@relief.hu
The study area and object
Ultra high-resolution single-channel seismic profiling provided a detailed picture
about the geometry of Pleistocene - early Holocene alluvial deposits underlying the
recent bed of river Tisza. The alluvial architecture of 10-20 m thick (10-30 ms twt)
sediments between the riverbed and its first seismic multiple has been imaged with a
resolution of 0.5 m horizontally and 0.1 m vertically (Tóth et al, 1997).
The ultra high-resolution seismic sections were acquisited along the temperate
climate, high sinuousity meandering Tisza river, which is the largest river within the
Pannonian Basin. From the Pleistocene onward due to moderate rate of subsidence
the ancestors of the Tisza and its distributaries have been filling up the basin in an
overall aggradational style, with minor and local events of incision only.
Seismic interpretation led to the identification of several distinct seismic facies
with characteristic bounding surfaces which were explained in terms of architectural
elements (Sztanó et al, 2002). The most important elements are the followings:
- Bundles of high amplitude oblique, tangential or sigmoidal parallel clinoforms
were interpreted as macroscale inclined strata sets (sensu Bridge 1993). Having a
strong, relatively flat basal reflector these were regarded as the result of lateral
accretion. The series of inclined reflections form several storeys, which are
corresponding to 5-7 m thick sediments, horizontally covering a distance of 250 m
up to 3500 m (!).
- Trough-shaped high to moderate amplitude parallel or converging reflections were
frequently found next to series of inclined reflectors. The troughs are 150-200 m
wide and 5-8 m deep. This geometry was interpreted as channel fill after natural
cut offs.
- Inclined or trough-shaped reflectors often cut sharply into horizontal, weak to good
continuity parallel reflections of significant length. These were interpreted as
vertically accreted fine grained overbank or floodplain deposits.
Both the lateral accretion deposits and the abandoned channel-fills indicate the
development of a relatively large river during Late Pleistocene- Early Holocene times
similar in size to the recent meandering Tisza. In series of lateral accretion deposits
longer than a few hundreds of metres a variation in dip angle of the inclined strata
sets is obvious. The aim of modelling would be to reveal the factors that influence
these geometrical variations, and to distinguish climatically induced
palaeohydrological effects from random meander excursions.
Former modelling of meander evolution
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Simulations by Bridge (1975) focused on changes in plan form and cross section with
respect to meander movement and increase of amplitude and sinuosity.
Scouring and filling produced the relief of the basal surface related to the slope of
lateral accretion surfaces, but angle variations were not adressed yet. Willis (1989)
recognized that point bar deposits thicken and inclined bedset surfaces become
steeper towards the bend apex and with increasing sinousity. Out of these effects the
change in sinuosity seems to be the more important. The role of direction and
position of cross-sections (outcrops) were also displayed. A more detailed modelling
and comparison with real outcrop situations was presented by Willis (1993). It is
shown that with increasing bend wavelength lateral accretion deposit thickness and
dip of bedsets decreases. The gradual reduction of discharges has the same effect on
geometry. Variations in dip angle of inclined bedsets produce two types of
disconformities within inclined bedsets: sets with low angle dips truncated by more
steeply dipping ones are intrepreted as the result of sudden increase in discharge;
while sets having steeper dips below the disconformity overlain by relatively less
dipping surfaces are resulted from a drop of sinuosity during chute cutoff. The above
modells also take variations in vertical grain size and transport direction into
consideration.
Variation in dip angle of inclined bedsets
One of the longest series of inclined bedsets forms an about 3 km long, 7 m thick
storey (Fig.1). Its basal surface runs 10 m below the recent river bed. The true dip of
the bedsets is very low (about 2-3o), but due to vertical exageration the subtle
variations in the dip angle are clear. The seismic section is rather straight in plan
view; the lateral-accretion bedset surfaces most likely represent an oblique section of
the ancient meander bend. These surfaces are often truncated by steeper or offlapped
by flatter ones, followed by reactivations.
The initial downcutting is relatively steep and is overlain by a series of
progressively steepening oblique reflectors. This 500 m long part of the section is
divided into bundles (1-5) by discontinuities, which having a larger dip truncates the
underlying strata, and follow each other in 100 m distances. On the following 1000 m
there is only one single erosional surface (7). However, another kind of discontinuity,
marked by onlaps of more flat lying reflectors is frequent (6, 8, 9, 10). From bundle 5
to 6a a gradual decrease of dip angles, from 6b to 7 an increase and from 8 to 11 a
decrease occurred. Parallel with this flattening a thinning of the unit took place. On
the following 600 m erosional truncations became frequent again, accompanied with
progressive increase of dip angles (11-15) and a thickening of the storey. In bundle 15
the dip angle decreases, in 16-17 it remains constant, but from 18 to 21 a gradual
decrease is evident, however the thickness of the unit does not change. The upper
portion of surface 21 is erosional and even shows a ridge and runnel topography.
Interpretation and discussion
According to modelling results the left side of the section (bundles 1-5) reveals the
birth of a bend with increasing sinuosity parallel with a progressive increase of peak
discharges in regular timespans. From 5 to 6a the growth of the bend wavelength can
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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be supposed followed by a renewed phase of increasing sinuosity (6b-7). With this
expansion the bend most likely reached its largest size, which also indicates the
greatest discharges ever reached. The frequent occurrence of erosional floods during
the beginning points to a variability of climate which later became balanced.
From unit 8 to 11 a considerable shallowing of the channel took place indicating a
gradual decrease of discharge, again with fluctuating climatical background. This
was followed by an increase of sinuosity, discharge and frequency of large, erosive
floods (11-15), coupled with the deepening of the channel. For a short time growth of
bend wavelength can be supposed (15) which was followed by a period of constant
uniform translation during stable conditions (16). After the deep incision (17) a
gradual widening of the channel without changing depth can be suspected, which
might have been associated with a slightly increase in discharge. Surface 21 can be
interpreted as chute cut-off.
Unfortunately from a seismic section paleo-transport directions cannot be read
in order to follow channel orientation and surface shape. Thus an alternative
interpretation for bundles 8-11 might be that the direction of meander migration
changes and the section goes from bend apex to inflection point. In that case it has
nothing to do with disharge variations. Having an excellent 3-D controll on exposed
lateral accretion surfaces and scroll bar morphology Diaz-Molina (1993) suggested
that all erosional surfaces between conformable lateral accretion units demonstrate
changes in channel displacement direction. Although this cannot be excluded the
observed consistent and repeated variations in the dip angle of the lateral-accretion
surfaces were not likely to be produced by random meandering.
If the above assumed variation of discharges is interpreted as the reflection of
climatic changes a geological time frame is needed. In lack of direct data the recent
rate of meander migration can be considered as the best analogue available. That was
between 0.5-1.5 m/year averaged from the last 120 years on this part of Tisza river,
thus deposition of the whole succession may took place during about 3000 years. The
formation of the river (1-5) as well as the growth of the meander bend (6-7) could
have happened at about the Pleistocene/Holocene boundary when the rise of the
temperature was associated with an amplified amount of precipitation and runoff
(climatical variability first followed by more stable conditions). Later on precipitation
decreased resulting in the decrease of discharge, reflected by shallowing of the river
(8-11) in the first part of the Boreal. Calculating with the same average rate of
meander migration later the increasing discharge (11-15) indicates the increase of
precipitation again, followed by constant high values (15-17) during at the onset of
the Atlantic. The end of the section may point to the maximum discharge attained
during the Early Atlantic. The above deduced climatic fluctuations are in accordance
with those observed by several means in the Pannonian Basin (Gábris, 1995).
Conclusions
Internal erosional surfaces indicate major floods in a recurrent period of about 100
years during periods of climate change. The variations in dip angle of lateral
accretion surfaces through changes of morphometric parameters (sinuosity,
wavelength, width/depth ratio) reveal periodic increases and decreases in discharge
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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due to climatic effects. The seismically studied fluvial deposits nicely reflect those
variations in precipitation which took place during the Late Pleistocene –Early
Holocene.
Acknowledgement
The seismic survey was carried out by the Geomega Ltd., Budapest. The study was
supported by the Hungarian National Science Found OTKA no. T.037724, T.032956
and T.034979.
References
Bridge J.S. (1975) Computer simulation of sedimentation in meandering streams. Sedimentology 22, 343
Bridge J.S. (1993) Description and interpretation of fluvial deposits: a critical perspective.
Sedimentology 40/4, 801-810
Diaz-Molina M. (1993) Geometry and lateral accretion patterns in meander loops. In: Marzo M. &
Puigdefabregas C. (eds.) Alluvial Sedimentation, IAS Spec. Publ. 17. pp.115-131, Blackwell, Oxford
Gábris Gy. (1995) River activity as a function of changing palaeoenvironmental conditions during the
Late Glacial – Holocene period in Hungary. In: Frenzel B. (ed). European river activity and climatic
change during the Late Glacial and Early Holocene, Fisher Verlag, 205-212.
Sztanó O., Tóth T., Magyari O., Magyari Á. & Horváth F. (2002) :Alluvial architecture from ultra highresoltution single-channel seismic survey of the meandering Tisza river, Pannonian Basin,
Hungary , 16th International Sedimentological Congress Abstract Volume 357-359
Tóth T., Simpkin P., Vida R. & Horváth F. (1997) Shallow water single and multichannel seismic
profiling in a riverine environment, The Leading Edge, 16/11, pp.1691-1695
Willis B.J. (1989) Palaeochannel reconstructions from point-bar deposits: a three-dimensional
perspective. Sedimentology 36, 757-766
Willis B.J. (1993) Interpretation of bedding geometry within ancient point-bar deposits In: Marzo M. &
Puigdefabregas C. (eds.) Alluvial Sedimentation, IAS Spec. Publ. 17. pp.101-114, Blackwell, Oxford
Fig.1. Variation in dip of inclined bedsets drawn from ultra-high resolution seismic
images were interpreted as lateral accretion surfaces (LA). Numbers mark
bundles.
see next page for enlargment
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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The Role of Numerical Sedimentary Process Models in Hydrocarbon
Exploration and Reservoir Characterization
Tetzlaff, D.
Schlumberger-Doll Research, 36 Old Quarry Road, 06877, Rifgefield, Connecticut, United States,
dtetzlaff@slb.com
Forward numerical models of sedimentary processes were initially developed as a
research tool in sedimentation. Their representation of physical sediment-transport
phenomena has increased their appeal in the oil industry as a complement to more
descriptive geostatistical methods. Here we report some of the successes and
difficulties we have encountered in the development and use of a siliciclastic
sedimentary process model for hydrocarbon exploration and reservoir
characterization.
A useful sedimentation model must represent natural processes in a practical
amount of computer runtime. This need is exacerbated by the fact that forward
models must often be run repeatedly in the search for the initial and boundary
conditions that cause the output to conform to observations. Efficient representation
of the processes of erosion, transport, and deposition appears to require the use of
more than one numerical method, depending on the depositional environment
represented. Steady flow situations (rivers at normal stage, long shore currents, etc.)
appear to be adequately handled by finite-difference schemes, whereas highly
unsteady flow involving sediment transport (floods and turbidites) is more
efficiently
represented
by
“particle”
numerical
techniques.
Users of a sedimentation model’s output (seismic interpreters and log analysts
among others) require that the information produced by the model (sedimentary
deposit geometry, lithology, and rock properties) be converted to a form that is
directly comparable to their data (seismic data and well logs). Therefore, we have
implemented a procedure to obtain petrophysical properties from a sedimentary
model’s output and developed a 3-D hybrid seismic modeling technique based on a
ray-plane-wave approximation. The resulting seismic sections outline lateral extent
and dip of the simulated deposits and exhibit amplitude variations with offset (AVO)
that are directly comparable with seismic data.
We show an application example in which we apply the methods outlined above to a
deep-marine reservoir analogue from the Tanqua Karoo Basin, South Africa. The
example suggests that the combination of these techniques forms a workflow that
constitutes a promising basis for expanding the application of sedimentation models
in the oil industry.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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Models that talk back
Tipper, J.C.
Geologisches Institut, Albert-Ludwigs-Universität, Albertstrasse 23B, D-79104 Freiburg, Germany,
john.tipper@geologie.uni-freiburg.de
1)
Each model that a scientist makes of a system is an expression of a particular
set of ideas. These ideas - they can be dignified by the terms ‘hypothesis’ or ‘theory’
depending on the amount of evidence that exists to support them - are expressed in
the model in a form in which they can readily be worked with; this form may be
physical, or mathematical, or graphical, or even verbal. There are two reasons for
expressing ideas in this way. Either it may be hoped that experimentation with the
model will help in understanding the structure and function of the parent system, or
it may be believed that the model can predict how that system will behave under
specified input conditions. Understanding and prediction can aptly be described as
the twin goals of scientific modelling.
2)
Understanding clearly must precede prediction, but how can a system ever be
known to be understood - or at least be known to be well enough understood to
allow a model of it to be used for prediction? There is a range of answers to this
question, from the principled to the pragmatic. The principled answer is that a
system should be taken to be understood only when it can be fully represented in
terms of fundamental physical laws. The pragmatic answer is that a system can be
taken to be understood as soon as any model has been made of it that can be shown
to predict how it will behave for a wide range of specified input conditions. The
principled position allows modelling only for the purpose of prediction; the
pragmatic position allows modelling both for prediction and for understanding.
3)
Modelling for prediction is carried out when a system is judged to be well
enough understood that a model of it can be used for prediction for the particular set
of input conditions that is of interest - this judgement is of course often entirely selfserving. Modelling for understanding is carried out when a system is judged not to
be well enough understood. Modelling for understanding takes two forms: the
testing of the ideas expressed in a model, and the exploration of the consequences of
varying a model’s assumptions or parameters. Modelling that involves testing is
essentially deductive in its nature - as is modelling for the purpose of prediction;
modelling that is exploratory can be inductive or deductive, depending on the
conditions under which it is carried out.
4)
The standard strategy employed when models are used for testing involves
running the model and its parent system under identical input conditions; the
behaviour of the model is then compared to the behaviour of the system. If the
behaviour of the model is identical to that of the system, the confidence that the
modeller has in the correctness of the ideas expressed in the model is increased; if the
behaviour of the model differs from that of the system, the confidence in the
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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correctness of those ideas is decreased. This strategy is attractively simple and is
therefore widely used.
Its simplicity is deceptive, however, and problems inevitably arise whenever it is
implemented in practice. The most substantial of these are: (1) the problem of
adequate access to a model’s parent system, (2) the problem of judging the
significance of differences in behaviour, and (3) the problem of allowing for
nonuniqueness. These problems are particularly acute for the types of models with
which earth scientists commonly try to work – i.e. for field-scale models of natural
systems operating over long periods of time.
5)
It is helpful to characterise models in terms of the degree to which they are
logically identical to their parent systems. A model that is logically identical to its
parent system is one for which the system is fully understood and for which the
input state is always known. A model that is not logically identically to its parent
system has free parameters or auxiliary hypotheses; the free parameters might be
being used to make up for deficiencies in the basic understanding of how the system
works, and the auxiliary hypotheses might be being used to make up for lack of
knowledge about the system’s input state. A model that is logically identical to its
parent system does not require testing; it can be used immediately for prediction, for
all of the allowable input states. A model that is not logically identical to its parent
system needs at least some testing; it can nevertheless also be used for prediction, for
some input states. The amount of testing that a model needs is measured by the
proportion of input states for which the model cannot be trusted to show the same
behaviour as the system itself; the amount of prediction possible from that model is
measured by the proportion of input states for which the model can be trusted. The
relationship between the amount of testing needed and the amount of prediction
possible is shown schematically in Figure 1, as a function of the extent to which a
model and its parent system are logically identical.
6)
The testing-prediction relationship curve defines two distinct styles of
modelling. One style (below the curve) is modelling that is inherently incapable of
being critical - it is what Medawar has termed ‘academic play’. It tests models less
frequently than is necessary, it uses them for prediction in circumstances where they
cannot be relied on to behave in the same way as their parent systems, and it
includes exploratory investigations that are essentially inductive (Baconian
experimentation). The other style of modelling (above the curve) is modelling
designed always to err on the side of safety. It tests models more frequently than is
really necessary, it uses them for prediction less frequently than would be possible,
and it includes exploratory investigations that are strictly deductive (Kantian
experimentation). The first style of modelling is prevalent whenever models are
made that have unconstrained auxiliary hypotheses and large numbers of free
parameters; such modelling says very little of value about the system concerned,
because models such as these do little more than obey the modeller who made them.
The second style of modelling is effectively possible only for models that are close to
being logically identical to their parent systems - these are models that talk back.
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7)
An example will be given of each of the two styles of modelling, both to
illustrate the essential differences between them and to point out their strengths and
weaknesses.
A model of landscape development in southeastern Australia provides the example
of ‘academic play’, and a model of sedimentary cyclicity provides the example of a
model that talks back.
Figure 1. The testing-prediction relationship curve separates the two styles of scientific
modelling.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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Utrecht, 9 – 11 October 2003
Modelling the impacts of climate change on erosion, sediment
production, and landscape evolution
Tucker, G.
School of Geography & the Environment, Oxford University, Mansfield Road, OX1 3TB, Oxford, United
Kindom, gtucker@nimbus.geog.ox.ac.uk
Sediment supply is one of the primary controls on deposition rate and stratal
architecture. In this talk I review analytical and numerical models of landscape
denudation, sediment production, and coupled subaerial erosion-deposition systems.
The present state of the art consists of a variety of different models. Most of these
represent fluvial and hillslope processes, though some attempts have been made to
capture glacial dynamics as well. All drainage basin evolution models are able to
reproduce branching drainage networks and ridge-valley topography, but these
models make different (and generally testable) predictions about transient responses
to tectonic, climatic, or eustatic change. Efforts at testing alternative models are
ongoing and involve a range of approaches, including tests based on case studies
with known initial and boundary conditions and known forcing.
Several lessons have been learned recently about the sediment-flux responses to
external (climatic, eustatic, and tectonic) forcing. Models predict, for example, that
when the forcing timescale is comparable to the geomorphic response timescale, the
nature of sediment-flux curves differs fundamentally between scenarios of tectonic
versus climatic forcing – the former producing a delayed but sustained response, the
latter producing an immediate but transient response. These response timescales,
and their sensitivity to factors such as source terrain size, can be derived from
analytical or numerical models, but their predictions are mostly untested. In terms of
climate forcing, recent work has unpacked the overly simplistic ‘wet versus dry’
thinking of the past and begun to reveal how particular aspects of climate change can
influence denudation rates and sediment supply. For example, theoretical work
implies that short-term climate variability can have a dramatic impact on sediment
production, which supports the hypothesis that climate change is responsible for
worldwide accelerated sedimentation in the late Cenozoic. Although the mechanisms
leading to geomorphic sensitivity vary, nonlinearity and sensitivity to highfrequency climate change seem to be general properties of many different
geomorphic systems.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Scaled models of syntectonic sedimentation – review of principles and
first results
Urai, J.L. & Kukla, P.A.
RWTH Aachen University
Sedimentary systems which are active under conditions of active tectonics show a
range of different types of non linear responses which are incompletely understood.
Scaled models are useful tools to understand the interactions in both sedimentary
and tectonic systems. However, experiments which might combine these two have
not been attempted yet. In this paper we review the basics of designing scaled model
experiments of both tectonic and sedimentary systems, and discuss the limitations of
current techniques.
Some of the limitations of current experiments have been resolved by a new sandbox
now in operation at Aachen University which operates submerged in water. This
way, models containing water-saturated layers of sand and clay can be deformed.
Recent developments in image analysis technology allow real-time high resolution
analysis of the displacement field at length scales less than a grain’s diameter, and
resolution of an unprecedented level of detail in the organization of deformation
patterns.
This system is suitable for experiments where a simple sedimentary system is
simulated during movement on an active fault. We present first results of such
experiments and discuss the scope for larger scale and more complex simulations
involving growth faults.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Outcrop and seismic constraints for 3D numerical stratigraphic forward
modeling
Van Buchem, F., Granjeon, D. & Eschard, R.
Institut Français du Pétrole, Rueil-malmaison, France
Stratigraphic forward modeling allows to quantify the interaction between the three
main “processes” that control sedimentation: accommodation (tectonism, eustasy
and compaction), sediment supply (clastic supply and carbonate production) and
sediment transport. A key problem, however, is to determine the relative
contribution and influence of each one of these parameters. The only way to address
this problem is to work with the best documented and understood case studies
available. In addition, the insight gained from them, feeds the memory of the model,
and can be used as constraints in less well documented studies.
In this presentation we will give two examples of carbonate systems, one mixed
carbonate/siliciclastic system, and two siliciclastic systems. In most of the examples
high resolution sequence stratigraphy has been applied to unravel the fine scale
architecture of these systems.
-
-
-
-
The first carbonate example is the Natih Formation of Cenomanian age (Upper
Cretaceous) that outcrops in northern Oman (van Buchem et al., 2002). Our work
demonstrated that in this formation twice an organic-rich intrashelf basin was
formed mainly controlled by the response of the sedimentary system to the rate
of sea level rise. Tectonism only played a minor role in the initiation of the
intrashelf basins. The stratigraphic modeling effectively produced these basins,
based on differential sedimentation rates of the carbonates in response to the sea
level fluctuations.
The second carbonate example is from the Upper Miocene in Mallorca. The work
by Pomar (2001) showed that a change in ecosystem caused a change from a low
angle ramp to a rimmed platform. Using the ecological parameters of this study
in the stratigraphic modeling (depth of carbonate production, type of producers),
allowed to reproduce this transition in stratigraphic organisation.
In the Lower Miocene of south central Turkey a mixed carbonate siliciclastic
system has been studied in seismic scale outcrops (Bassant, 1999). Here the
interplay between carbonates and siliciclastics was the main challenge, with
siliciclastics inhibiting carbonate sedimentation during highstand and fall of sea
level (around the point source), while during sea level rise an ecological
‘window’ was created for carbonate sedimentation. Introducing a sensitivity to
siliciclastic input for the carbonate producers permitted to model this complex
interfingering pattern.
The Eocene of offshore Brasil has been studied using wells and high resolution
3D seismic (Pinheiro-Moreira, 2000). This database allowed to determine the 3D
organisation of the turbidite system. Stratigraphic modeling led to a validation of
the seismic analysis in this deep offshore environment, and to a better
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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understanding of the timing, geometry and facies of turbidites in two different
basin margin settings (ramp and shelfbreak; Granjeon et al., 2001).
- The last example concerns the Colorado basin in Argentina. This basin was
initiated during an early Mesozoic rifting period, followed by a Cretaceous to
Miocene sag period, to ultimately reach the present day passive margin
configuration. Only the upper third (Upper Cretaceous to Quaternary) of the
sedimentary column is covered by wells, located at the margins of the basin. A
stratigraphic simulation was constraint by excellent seismic data and these few
wells, to quantify the geological parameters and evaluate the facies distribution
in the non-drilled areas (Mancilla et al., 2002). Basin modeling was then used to
asses the hydrocarbon potential of this basin (Haring et al., 2002).
Though stratigraphic modeling is in many ways a powerful tool to test the coherency
and imagination of the geologist, the ultimate test of the modeling results is the
comparison with the hard field and subsurface data. The case is made here that the
real advances in stratigraphic modeling will come from top quality geological
studies, allowing to quantify the parameters of dynamic sedimentological models in
a high resolution time framework.
Acknowledgements: Dionisos is a 3D stratigraphic forward model, developed by IFP
and a consortium of companies including Total, Shell, Repsol-YPF, Chevron-Texaco,
Petrobras, Agip, IMP, and Pemex.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Impact of discharge and sediment flux on Basin Margin Architecture: An
experimental approach
Van den Berg van Saparoea, A.P., Postma, G. & Dalman, R.
Universiteit Utrecht, Faculteit Aardwetenschappen, Budapestlaan 4, 3584 CD, Utrecht, The Netherlands,
apvdbvs@geo.uu.nl
In most cases it is very difficult to evaluate the stratigraphic record in terms of
formational processes. Important parameters in fluvial-deltaic settings are relative
sea-level and the ratio of discharge (Q) and solid load (Qs). We use analog modeling
for unraveling the role of each of these formational processes. The changes in the
modeled system are monitored by means of digital elevation maps (DEM's) of the
surface, and are calibrated against the last glacial cycle stratigraphic record of the
Colorado (Texas, USA) fluvial-deltaic system.
The influence of relative sea-level at constant Q/Qs ratio has been investigated
in a previous series of experiments (Van Heijst et al. 2001, Basin Research). In the
experiments described here Q/Qs ratio is varied, while the rate of change in relative
sea-level is kept constant. Our preliminary results indicate that the efficiency of
sediment transport increases with higher Q/Qs ratios. A system with high Q/Qs ratio
is predominantly progradational, while a system with a low Q/Q s ratio shows
progradation and aggradation over the entire shelf. Furthermore, a high Q/Q s ratio
leads to increased headward erosion rates in the fluvial valleys incised in the shelf.
Therefore, connection of the shelf valleys with the trunk river occurs earlier than in
case of a lower Q/Qs ratio, which means that even though the system is fluvial
dominated (i.e. strongly progradational), the influence of sea-level fluctuation on the
fluvial domain is strong. A sudden increase in discharge (and thus increase in Q/Qs
ratio), as is postulated to have occurred in the Colorado system, results in the model
in instantaneous adjustment (lowering) of the equilibrium slope in the fluvial valley,
and increased sediment yield at the river valley mouth. The climate shift also causes
increased avulsion frequency and aggradation over almost the entire shelf. If the
pulse coincides with the late sea-level fall (past the fall inflection point), it will delay
the onset and magnitude of headward erosion on the shelf and so decreases the
influence of sea-level on the river system. A shift in climate can apparently have a
strong influence on the development of the system, modifying importantly the
impact of glacio-eustatic sea-level changes on the system.
In conclusion:
-
High Q/Qs ratios produce strongly progradational systems, high knickpoint
migration rates in the valleys and relatively early connections of shelf and
fluvial valleys;
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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-
Low Q/Qs ratios produce predominantly aggradational systems, low
knickpoint migration rates and relative late connections of shelf and fluvial
valleys;
-
Climate shift towards wetter conditions causes a strong sediment pulse at the
river mouth, increases avulsion activity and so enhances wide distribution of
sediment over the shelf.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
High resolution 3D Forward Stratigraphic modelling of Cretaceous
carbonate platform systems
VAN DER ZWAN, C.J.1, MASSE, J.-P.2, BORGOMANO, J.1, 2, LAMMERS, H.1 & FENERCI-MASSE, M.2
SIEP-SEPTAR, P.O.Box 60, 2280 AB, Rijswijk, The Netherlands, Kees.vanderZwan@shell.com
University of the Provence, Labo Sedimentologie, 3, place Victor Hugo, 13331, Marseille, France,
jborgo@up.uni-mrs.fr
1)
2)
3D Forward stratigraphic modeling is applied in the petroleum industry to predict
the presence and quality of reservoirs, source rocks and seals both on exploration
and production scales. These models consist of 3-dimensional representations of
facies attributes that can be related to physical properties of reservoirs, seals and
source rocks. The forward modeled facies and geobodies can also be used to
constrain production scale reservoir architectures. The main input parameters to the
3D stratigraphic modeling in any depositional settings are: (1) tectonic subsidence,
(2) initial bathymetry, (3) eustatic sealevel and (4) sediment supply. In a clastic
setting, the latter parameter reflects the amount of sediment entering the system. In a
carbonate setting this reflects in situ production and re-distribution of carbonate
material. The first three parameters can be obtained or reconstructed from standard
seismic and deterministic geological interpretation or are directly availa ble from
regional sources. The fourth parameters, carbonate production is the subject of
ongoing research, is dependent of many other ecological and environmental
parameters and requires sensitivity analysis
Recent high-resolution outcrop studies of Lower Cretaceous systems in Southern
France improved our understanding of the development of Cretaceous carbonate
platforms. This data set has shown the interrelationships between water depth,
energy levels and the various facies associations in a 'Rudist' platform setting. These
data have been used to calibrate the 3D forward stratigraphic modelling of similar
Cretaceous carbonate platform systems in the subsurface at the scale of producing oil
fields.
The software package DIONISOS accurately modelled the stratigraphy and facies
distribution of a Cretaceous carbonate platform in the Cassis and Mont Puget
outcrops near Marseille (SE France) and in a Cretaceous producing field. In Cassis
and Mont Puget, inner and outer platform settings were modelled, respectively,
whereas in the Cretaceous Field various scenarios were used to test the sensitivity of
the controlling parameters. Evaluation of the resulting models shows that the most
important parameter in stratigraphic forward modelling of such carbonate platforms
is changes in "accommodation space". This parameter determines the space available
to be filled by carbonate growth. The changes in carbonate growth potential have less
impact, provided carbonate growth is sufficient to fill the space created.
Forward models have been built for inner and outer platform settings both in
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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Utrecht, 9 – 11 October 2003
outcrops and in producing fields. Independent calibration of these forward models
indicates that they compare closely, with a vertical resolution of one meter, with
stratigraphic architecture of outcrops and fields.
The ability of stratigraphic forward modelling to build such accurate and highly
detailed models demonstrates that stratigraphic forward modelling is a valuable new
technique not only to improve our understanding of the subsurface, but also for the
prediction of reservoir architecture both on an exploration and production scale.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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Utrecht, 9 – 11 October 2003
Combination of Structural Balancing, Reverse Basin and Forward
Stratigraphic Modelling: Southern Cantabrian Basin (NW-Spain)
Vesolovsky, Z.
Geologisch-Paläontologisches Institut, University of Heidelberg, Im Neuenheimer Feld 234, D-69120,
Heidelberg, Germany, zbynek.veselovsky@urz.uni-hd.de
The processed transect (24km) situated at the southern margin of the Cantabrian
Mountains (NW-Spain) comprises the whole basin infill between top of basement
(560Ma) and time of maximal burial (34Ma). This part of the Variscan orogen is
represented by a foreland thrust and fold belt, further shortened during Alpidic
orogenesis, offering magnificent outcrops in each individual thrust sheet. In order to
carry out basin modelling at this tectonically affected region, a multidisciplinary
approach of detailed field mapping, structural balancing and stratigraphic modelling
is required.
Total tectonical shortening of the basin, derived from 2D structural balancing of the
deformed basin infill, amounted to 54% at minimum. 2D reverse basin modelling
investigated the quantitative development of the basin architecture and long-term
evolution of accommodation space in time. Stratigraphic forward modelling
quantified sedimentary processes (erosion and sedimentation rates), refined the
sequence stratigraphic model, and offered geometrical minimum/maximum models
of the sedimentary patterns.
Three major subsidence trends obtained from 2D reverse basin modelling reflect
different plate-tectonic development stages of the basin. Precambrian to Ordovician
times recorded uniform tectonic subsidence rates (-11 to 19 m/Ma). Differential
subsidence triggered by local tectonics (-28 to 66m/Ma) generates marked changes of
depositional environments (Silurian until Late Devonian). Our study indicates major
influence of total subsidence and sediment supply liable for the remarkable
alternating siliciclastic and carbonate deposits during the Devonian. Eustatic sealevel fluctuations were only of subordinate importance. In the Upper Carboniferous,
eastward migrating depocentres coupled with high rates of tectonic subsidence (-177
to 300 m/Ma) reflect movements of the Variscan front.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
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Utrecht, 9 – 11 October 2003
Non-unique sequence stratigraphic architectures
Waltham, D., Udofia, M. & Nichols, G.
Department of Geology, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK,
d.waltham@gl.rhul.ac.uk
Sequence stratigraphic architectures are controlled by subsidence, eustatic sealevel
and sediment supply. A key problem, both for real-world architectures and for
computer models, is that there may be more than one combination of these controls
which produces the same geometry. In this paper we investigate the general
conditions under which this non-uniqueness occurs and we illustrate this using
computer generated cross-sections which, indeed, show identical architectures
resulting from differing control-functions.
The simplest case is that of a non-erosive model with a constant coarse/fine ratio in
the input sediment. Such models produce identical results for all runs which have
the same sealevel versus sediment supply curve. More general cases with timevarying coarse/fine ratios and time-varying tectonics can be handled by requiring
these curves to also be fixed when plotted against sediment supply.
All of the preceding examples are special cases of models in which the incremental
change in stratigraphy is controlled by the amount of accommodation space but not
by its rate of creation or destruction. This requirement is violated if an erosion rate is
introduced to the model. Surprisingly, however, multiple near-identical geometries
can still be produced for erosive models provided the sealevel curves are suitably
adjusted.
Finally, the methodology derived from the above conclusions is applied to a 2D
seismic line from the Baltimore Canyon.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Insights into Carbonate Platform Drowning Mechanisms using
Stratigraphic Forward Modeling
Warrlich, G. & Burgess, P.M.
Shell International Exploration and Production B.V., P.O.Box 60, 2280 AB Rijswijk, The Netherlands
Mechanisms of carbonate platform drowning remain poorly understood, since
modern production rates imply that even the most rapid rates of relative sea-level
rise are insufficient to outpace production. Other proposed drowning mechanisms
include water temperature changes, changing nutrient levels, plate movement into
higher latitudes, erosion or stripping of sediment from platform tops by transport,
and rapid water depth increase during lag periods (deep flooding). We have used
two different stratigraphic forward models to investigate the operation of the latter
two mechanisms. One model concentrates on sediment transport on the platform
top, and the other that uses cellular automata to control carbonate productivity and
hence simulates a lag process. Model runs combine long term subsidence with a 100
ky eustatic signal and typical shallow water carbonate production rate to determine
under what combination of these parameters drowning occurs.
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Analogue and numerical forward modelling of sedimentary systems; from understanding to
prediction
Utrecht, 9 – 11 October 2003
Modelling Source Rock Distribution and Quality Variations:
The New OF-Mod 3D Technology
Zweigel, J.
SINTEF Petroleum Research, S.P. Andersens veg 15b, 7465 Trondheim, Norway, Janine.zweigel@iku.sintef.no
In exploration the ability to predict hydrocarbon occurrence and quality variations
within a prospect - prior to drilling - is of large importance. Particularly, recently
developed 3D modeling techniques are gaining significance with respect to
volumetric hydrocarbon predictions. The source rock is the basis of every petroleum
system and the first pre-requisite for a hydrocarbon accumulation to occur. But
source rock distribution, type and quality variations are still among the least
constrained parameters during basin modeling studies.
The OF-Mod program is a process-based modeling tool, which mimics the
development and the variation of source rock facies. Consequently, it allows
quantitative prediction of source rock potential away from well control and results in
a significantly improved input for kinetics, expulsion and migration studies. The
concept was designed in early 98 and in meantime the 2D version of the software has
been applied in many national and international studies and has gathered scientific
approval.
The further development of the software into a 3D version is a consequence of the
technological evolution during the last years and will lead to a significantly
improved picture of the complex interaction of processes effecting source rock
deposition. In a theoretical example we will illustrate the possibilities, differences
and consequences of 2D and 3D source rock models with respect to quantitative
estimates. Additionally, we will show the capabilities of the new 3D tool with special
attention to integrated, high-resolution basin modeling studies and, in contrast,
application in exploration frontier areas, where only little information is available.
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