Modelling Unconventional Wells
with Resolve and Reveal
Juan Biörklund (Gauloise Energía)
and
Georg Ziegler (Wintershall Holding)
Modelling Unconventional Wells
Reveal Features
Designed to study specialized near well bore effects and
assess their impact on the production from the reservoir
 Adsorption
 PVT Modelling
 Diffusion
 Reservoir Modelling
 Rock Mechanics
 Well Modelling
 Rock Failure
 Chemical EOR
 Fracturing
 Water Chemistry
Modelling Unconventional Wells
Capabilities (Resolve & Reveal)
 Quick Calculations
 Tight reservoirs with complex well geometries
 Systems with up to 20,000 wells with 100 wells being
drilled per month
 Shale Oil / Gas Wells
 Horizontal, inclined and fractured wells
 Gas adsorption, diffusion, directional stress dependent
permeability variations etc...
Modelling Unconventional Wells
Concept
 Dimensionless transient reservoir response
capturing the well, fracture and reservoir geometry
 Dimensionless pseudo-pressure pseudo-time (pD tD)
 Match this response to production history
 Modify reference parameters k and phi(rw2)
 Adjust PVT reference conditions for pD and tD
Modelling Unconventional Wells
Concept (cont.)
 Perform predictions
 Use matched pD tD and super-position to predict Pwf
 Transient IPR for rate estimation
 Well scheduling
 Automate the procedures using visual workflows
 Model definition and workflow in Resolve
 Indirectly access simulation capabilities of Reveal
Modelling Unconventional Wells
Shale Gas Well
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Modelling Unconventional Wells
Microseismic
Frac Xf is 3 -5 x longer
than seen in FracPro,
proved with Microseismic
Multi-Fracs does not interfear
near wells (approx. 300m)
(Sketch not same as seen)
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Modelling Unconventional Wells
Fracture Input Parameters
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Modelling Unconventional Wells
Fracture Finite Element Grid
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Modelling Unconventional Wells
History Match
 History match a shale well
- Additional Input Data  Young’s modulus (248000 bar).
 Poisson’s ratio (0.275).
 Biot’s coefficient (0.75).
 Langmuir adsorption curve (70 scc/g).
 Fracture permeability variation (no data).
 Compaction table (Palmer & Mansoori – SPE 52607).
 Fracture geometry and properties (NRT Log & Gohfer)
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Modelling Unconventional Wells
History Match
History matching : Reveal model
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Modelling Unconventional Wells
Input Parameters
Modelling Unconventional Wells
Measured
Pressure
Rate
History Match: Reveal Model
Calculated
Pressure
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Modelling Unconventional Wells
pD tD Curves - Resolve
 pD tD curves
 Why
 A method that allows us to perform rapid calculations
with complex well geometries
 What they are
 Dimensionless transient reservoir response that
captures the well, fracture and reservoir geometry
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Modelling Unconventional Wells
pD tD Curves - Resolve
pD tD curves (pseudo-pressure pseudo-time)
6.3266  10 3  2kh P0 dp
pD 
p B
Q
24  0.2637 10 3 k
tD 
rw2

t
0
dt
cT
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Modelling Unconventional Wells
pD tD Curves - Resolve
 Optimization
 Resolve - Powerful Optimizing Tool
on Field Level Production
 Why Resolve
 Handles large number of wells
 Easy to analyze well performance
 Infinite scenarios to find best match
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Modelling Unconventional Wells
pD tD Curves
Use GAP with Eclipse / Reveal / pD tD
One well
Reveal
Model
One well
pd td
curve
Two well
Eclipse
Model
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Modelling Unconventional Wells
Resolve: Modelled vs. History
Modelling Unconventional Wells
Shale Oil Well
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Modelling Unconventional Wells
Oil Models: Resolve & Reveal
Issues
 No gas break-through seen in the simulation
 What is the frac geometry causing this behaviour?
 Tight Reservoir Module uses only analytical method (pD tD)
 3 Fracs simulated as one, inflow problems
Solutions
 Model the fracs explicitly with Reveal frac gridding option
 Evaluate resulting pD tD curves from analytical vs. numerical
 Detailed Resolve model explains where GOR increase when
pressure is below Pb at certain fracs
Modelling Unconventional Wells
Resolve pD tD Match
Dimensionless parameters – no geometry info
Modelling Unconventional Wells
Resolve Workflow
Modelling Unconventional Wells
Control Reveal with Resolve
Setup Resolve model and ran several cases to test sensitivity
on different parameters and interaction between them such as:
 Porosity, Stimulated K, Matrix K
 Fracture half length, Fracture height
 Stimulated Rock Volume (SRV)
 Compressibility
RESOLVE Logic
Modelling Unconventional Wells
Resolve / Reveal Sensitivities
Case_Name Porosity Permeability Compressibility Fracture Half Length Fracture Height
Case_24
0.04
0.0008
1.00E-05
262
82
Case_25
0.04
0.0008
1.00E-05
262
82
Case_26
0.04
0.0008
1.00E-05
262
82
Case_27
0.04
0.0008
1.00E-05
262
82
SRV
13
13
13
13
MatrixK
0.0001
0.0002
0.0003
0.0005
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Modelling Unconventional Wells
Oil Reservoir Model
What is different between a Resolve analytical and a
Reveal numerical model?
Transfer fracture model from Resolve tight module to
Reveal to back calculate geometry.
Modelling Unconventional Wells
Reveal Oil Reservoir Model
Pressure after
one month
Model variable compaction table, stress dependent
perm and changing cleat compressibility
Modelling Unconventional Wells
27/11/2013
02/03/2014
30/06/2014
3.74
3.80
3.65
3.90
3.96
Porosity Reduction with Pressure
4.01
Effect of Cleat Compressibility
Modelling Unconventional Wells
12/12/2013
31/01/2014
30/06/2014
36.0
37.1
38.2
39.3
40.4
Reduction of Oil Density over Time
41.5
Changing Oil Density over Time
Modelling Unconventional Wells
Reservoir Model - Conclusions
 Porosity and compressibility have similar effects on BHP
match
 Changes on SRV affects the late match
 Stress - Permeability function has an effect on the transient
behaviour (early decline / build up)
 BHP calculation need careful considerations due to the
instability of low rate wells.
 Stress dependent permeability needs to be included in the
Reveal models to obtain a match
Modelling Unconventional Wells
Thank you for your attention
Questions?
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