Package 1
Origin, Deposition Mechanisms, Exploration
and Occurence of Crude Oil and Natural Gas
Reservoir Engineering, Forecasts, Deep
Drilling and Production Engineering
Composition and Classification of Crude Oil
and Natural Gas
Transportation and Storage of Crude Oil and
Natural Gas
Definition
Crude oil is the name given to all organic
compounds which are liquid under reservoir
conditions.
Petroleum composition:
- hydrocarbons
-S, O, N, P compounds
-metal compounds (V, Ni, Cu, Co, Mo, Pb, Cr, As)
H2S and water
Elementary composition: C 79,5-88,5%, H 10-15,5%
Constituents of petroleum
Alkanes
Naphtenes
Aromatics
Classification of crude oils
Paraffin based -found in deeper zones
Naphtene or asphalt based –found in
upper level
Mixed-based –found in middle zones
Composition on worldwide basis:
~30% paraffins, 40% naphtenes, 25%
aromatics
Natural Gas
Dry and wet natural gases
Components: methane, higher
hydrocarbons, nitrogen, carbondioxid,
hydrogen sulfide, helium
Associated gas, closely connected to
crude oil
Natural gas---non-associated
Formation of crude oil
predominantly of organic origin
Petroleum source rock-deposits in sedimentary basin contain
organic residues of terrestrial, limnic, fluvial and marine originconversion under anaerobic conditions-resulting in bitumen or
kerogen
Source rock should contain 0,5% TOC
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Anoxic zones: nonmarine lakess (lake Tanganyika), closed inland seas
with positive water balance (Black Sea deep zones), ascent of marine
current from greater depths (Benguela current Africa, Humboldt current,
Peru), open ocean (global climatic warming with large transgressions in
Jurassic and middle Cretaceous period)
Crude oil formation from phytoplankton, bacteria-in the Silurian—
Devonian period
Formation: organic material in sapropels is decomposed, decayed
by anaerobic bacteria, organic material adsorbed onto fine clay
particles, which sink to the sea floor. Sedimentation condition in
Pliocene were similar to that of novadays in the offshore regions of
the sea.
Hydrocarbon formation
Diagenesis, Catagenesis,
(at depths of 1000-5000 m and 175 oC) Metagenesis
Migration of oil droplets
from argillaceous source rocks into porous reservoir rocks
Lateral migration through capillary paths
Vertical migration- fine fissures
During migration occurs separation from water,
gravitational separation: gas-oil-water
Chemical degradation leads to smaller and more
stable compounds
Maturation process concludes with the
conversion to methane
Reservoir rocks and trap structures
Fluvial sand, Beach and barrier sand, Wind-blown sand, Marine platform sand
Deep water sand, Reefs, Reef limestone debris, Chalk
Occurences
Production and reserves
Production and reserves
Oil exploration
preliminary exploration, exploratory wells
Geological exploration
Satellite images
Examination of rock samples
Stratigraphic investigations
Geophysical investigation
Magnetic measurements
Gravimetric measurements
Geoelectric measurements
Seismic methods
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Refraction
Reflection methods 3D method
Geochemical investigation
Exploratory drilling
The entire exploration-to-production
chain was reviewed and adapted to
greater water depths:
1. The development and use of (3D) seismic was
intensified.
2. Innovative drilling and production structures were
designed. Because these structures could not be
installed on the seabed at such great depths, FPSO
(Floating Production Storage and Offloading) and TLP
(Tension Leg Platform) systems were developed.
3. Efforts were made to come up with new materials for
the flexibles (able to withstand high pressures at great
water depths, etc.).
4. Horizontal and multibranch wells came into general
use, reducing the number of wells.
Estimated proved crude oil reserves in the world
(A)
Liquid petroleum consumed in the United States during the
past 50 years came from three sources
Main parameters for Conventional oil
Measurement
Produced-to-date
Reserves
Discovered-to-date
Yet-to-Find
Measure
873 Gb
928
1801
149
Yet-to-Produce
1077
Ultimate recovery
1950
Current consumption (2001)
Current discovery rate
Current depletion rate (ann.
prod. as % of Yet-toProduce)
22 Gb/y
6 Gb/y
2%
Peak Oil. It truly is a turning point for mankind
Conventional oil - and that will be defined - provides most of the oil produced today,
and is responsible for about 95% all oil that has been produced so far.
It will continue to dominate supply for a long time to come. It is what matters most.
Its discovery peaked in the 1960s. We now find one barrel for every four we
consume.
Middle East share of production is set to rise. The rest of the world peaked in 1997,
and is therefore in terminal decline.
Non-conventional oil delays peak only a few years, but will ameliorate the
subsequent decline.
Gas, which is less depleted than oil, will likely peak around 2020.
Capacity limits were breached late in 2000, causing prices to soar leading to world
recession.
The recession may be permanent because any recovery would lead to new oil
demand until the limits were again breached which would lead to new price shocks
re-imposing recession in a vicious circle.
World peak may prove to have been passed in 2000, if demand is curtailed by
recession.
Prices may remain weak in such circumstances but since demand is not infinitely
elastic they must again rise from supply constraints when essential needs are
affected
Oil price of today:
Crude Oil, Gasoline and Natural Gas
Futures
Prices for August 23, 2004
NYMEX Light Sweet Crude
-0.67
$47.46.05
IPE Brent
-0.51
$43.03
Gasoline NY Harbor
-0.0098
$1.2575
Heating Oil NY Harbor
-0.0149
$1.2147
-0.242
$5.310
NYMEX Natural Gas
Conclusion about reserves
Peak oil is a turning point for Mankind,
when a hundred years of easy growth
ends. The population may be about to
peak too for not unrelated reasons. The
transition to decline is a period of great
tension when priorities shift to selfsufficiency and sustainability. It may end
up a better world, freed from the
widespread gross excesses of to-day.
Reservoir engineering
Porosity
Physical properties of the pore saturating
fluids: density, compressibility, viscosity
Reserves = Resources x Recovery factor
Multiphase flow
Recovery factors: microscopic, areal,
vertical
The oil, gas and water distribution
in a pore
a) Water; b) Gas; c) Oil; d) Rock
Oil recovery efficiency
a./ depletion drive
b./ external gas drive,
small gas cap
c./ external gas drive,
large gas cap
d./ water drive
Modeling of reservoir and
production performance
Material balances method
Reservoir simulation
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Steady-state flow
Unsteady-state flow
Decline curve methods: exponential,
harmonic, hyperbolic
History of drilling
Deep drilling engineering
a) Parked drill pipe;
b) Drill hook; c)
Rotary swirrel; d)
Flexible hose; e)
Rotary table; f)
Preventer; g)
Vibrating screen
(shaker); h) Pit; i)
Cement sheath; j)
Casing; k) Hollow
drill pipe; l)
Circulating drilling
mud; m) Drill collar
as part of the drill
string; n) Roller cone
bit; o) Rock strata; p)
Reservoir rock
horizon
Rotary drilling
Drilling tools: roller
bit
Drilling mud:
thixotropic liquid,
contains additives,
like bentonite,
cellulose,
emulsifiers,
inhibitors, density
is between 1.1
and 1.4 g/cm3
Horizontal drilling
with active
steering
Various types of bit
A) Roller bit with
coarse teeth (for soft
formation); B) Roller
bit (for medium hard
rock); C) Roller bit
with fine teeth (for
tough rock); D) Roller
bit with hard metal
inserts (for very hard
formations); E) Roller
cone bit; F) Jet bit; G)
Diamond full-hole bit
Horizontal drilling strategies
A) Conventional; B) Drainhole, medium radius technology; C) Drainhole,
short hole technology
Mining drilling method
Externally and internally smooth drill pipe
Greater drilling progress
Geophysical borehole measurements:
electrical methods, sonic measurements,
radioactivity measurements, determination
of geophysical fields
Productivity tests before casing, short in
duration because unstable borehole
Samples from the reservoir content,
chemical and physical studies
Schematic diagram of double core barrel
a) Coupling to drill pipe; b) Overshot for pulling
out with wireline; c) Outer tube, rotates core
bit; d) Inner tube, nonrotating; e) Bearing; f)
Mud passage; g) Ball valve; h) Core catching
spring; i) Core catching cone; j) Mud channels
Comparison of oil and mining core drilling
A) Oil core drilling (double tube
core bit); B) Mining core drilling
(cable core bit)
Key deep offshore technologies
Deep Offshore Production Records
Casing and cementation
Several concentric strings of
casing pipes installed
according to geological and
engineering requirements
partly during drilling.
Casing is cemented
Loads on casing:
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Differential pressure
Radial component of the
formation stress
Tensile strength from own
weight
Bending stress, especially in
horizontal holes
Thermal stresses
Tubing string with packers
transports the fluid produced to
the surface
Cementing
1. Massive bond of casing and
formation
2. Isolation of permeable
formation
3. Corrosion protection
Cement + water + additives =
slurry
pumped through the borehole into
the annulus between casing
and formation, at elevated
temperatures retarders and
antifriction agents must be
added.
Production engineering
The purpose of the exploitation and production planning
of hydrocarbon reservoir is to produce optimum amount
of sealable products at minimum cost and with close
attention to all aspects of safety and ecology
Problems in oil production:
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Time of water injection, adjust the pressure
Dependence of the productivity index on viscosity of the oil and
water cut
Gas production and availability in the gas lift method
Advantages and disadvantages of the artificial lift methods
In gas production:
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Occurence of toxic and problematic substances
Heterogeneous multilayer and selective water incursion
Avoiding blowouts
General production engineering
Completion, Setting up production
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Wellhead, casing, cementing, tubing strings,bottom hole completion: „wireline
equipment”. Two types: open-hole completion, casing on top of producing
formation
Perforation
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tubing-coupled perforating, it is a controlled explosion
Well and reservoir treatment
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Well treatment
Obstruction can be caused: solids from the mud, water block, swelling of the
clay, chemical precipitation, emulsification.
Obstructions can be removed by acid treatment (HCl or HF, surfactant)
Reservoir bed treatment: pressure acidizing, hydraulic fracturing, injection of oil,
water or acid together with viscosity enhancing agent, proppant (fluvial sand)
Workover
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Workover hoist, wireline technique, coiled tubing, diameter 2,54-5,08cm, used at
a depth of up to 5500m
Horizontal wells: open hole, open hole with slotted or prepacked liner, slotted
liner with external casing packers in the open hole, cemented and perforated
liner.
Bottom-hole equipment in the reservoir zone
A) Main dolomite, uncased; B) Carboniferous, casing with liner; a)
Tubing, 2 7/8 inch (2.22 cm); b) Cement; c) Production packer; d)
Casing, 7 inch (17.8 cm); e) Liner hanger; f) Liner, 5 inch (12.7 cm)
Tubing-conveyed perforation (TCP)
Oil production engineering
1. Flowing
production
2. Gas lift
3. Centrifugal
pumps
4. Piston pumps,
sucker rod or
hydraulic
Continuous gas-lift operation
A) Schematic; a) Annulus; b) Valves closed; c) Tubing; d) Valves open; e)
Production zone; B) Pressure distribution at different depths; a) Annulus
pressure; b) Pressure curve in tubing for production well; c) Pressure curve
in tubing for inoperative well
Different types of pump
A) Subsurface rod pump with walking beam drive; B) Electric submersible
centrifugal pump; C) Hydraulic subsurface piston pump with pressure oil supply
in the open system;
a) Casing; b) Tubing string; c) Wellhead; d) Pump rod; e) Subsurface pump; f) Drive pump, g) Production
pump; h) Pressure oil pump with i) Pressure raising pump on the suction side; j) Motor; k) Sealing
adaptor; l) Gas separator; m) Nonreturn valve; n) Tubing drain valve; o) Three-core cable; p) Circulation
piece; r) Pressure oil tank; s) High voltage transformer; t) Autotransformer; u) Switch cabinet; v) Walking
beam; w) Gearing; x) Tubing anchor; y) Production packer
Collection and treatment of crude oil
Gas separation
Dewatering and desalting
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Emulsion breaking: early feeding of demulsifier,
moderate heating, separation in a tank
Special problems in crude oil production
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Paraffin precipitation
Chemical precipitates
Sand: safe production rate, filters, consolidation by
resins
Corrosion
Flow diagram of an oilfield
a) Compressor; b) Drying; c) Line; d) Gas separator; e) Heater; f)
Separator; g) Desalter; h) Tank; i) Secondary sedimentation; j) Filter
Natural gas production engineering
Special requirements in natural gas
production
High pressures and pressure differences
Extreme temperature differences
Aggressive gas constituents
Gastight tubing, special sealing materials
Controlled and monitored production
Safety at the surface, underground safety
valves
Deep storage reservoirs
Sour gas well
a) Well head; b) Anchor casing; c)
Cement; d) Intermediate casing; e)
Injection annulus; f ) Tubing; g) Production
packer; h) Liner; i) Perforations
Treatment
of natural
gas
Sulfur removal
Removal of
mercury
Dehydration
Removal of
hydrocarbons
Removal of
carbondioxid
and sulfur
components
Dehydration and cooling of natural gas
a) High pressure separator (free water knockout); b) Heater; c) Air
cooler; d) Separator; e) Joule – Thomson valve; f ) Gas – gas heat
exchanger; g) External cooling system for low-pressure wells
Hydrocarbon removal from natural gas
a) – c) Adsorbers; d) Heater; e) Cooler; f ) Chiller; g) Separator; h) Phase
separator
Physical-chemical scrubbing of natural gas
a) Absorber; b) Air cooler; c) Regenerator; d) Air condenser; e) Intermediate
flash stage with reabsorber; f ) Reboiler; g) Phase separator; h) Expansion
turbine
Liqiud oxidation process
Absorption of
hydrogensufide
Oxidation to sulfur
Reoxidation of active
component with air
Separation of
elementary sulfur
a) Absorber; b) Oxidizer; c) Settling tank; d) Centrifuge;
e) Recirculating pump; f ) Air blower; g) Chemical
additive pump; h) Sulfur slurry pump; i) Sulfur melter
Membrane separation of impurities
Adsorption
processes
Activated charcoal,
zeolites
Complete
natural gas
treating
plant
a) Sour gas
manifold;
b) Town gas
manifold;
c) Disposal well
– · – · – Steam;
– – – – Condensate
Liqiud Natural Gas
Liquefied natural gas on low temperature:
-160oC
Pretreat the gas
Refrigeration
Storage
Transportation: tankers
Nine-stage cascade liquefaction process
a) Compressor;
b) Condenser;
c) Accumulator;
d) Phase
separator;
e) Heat
exchanger
Underground storage facility for natural gas
European
natural gas
pipelines
Trans-Alaska pipeline south of Delta Junction. The pipeline
extends 800 miles from Prudhoe Bay to Valdez.
Alaska Range is in the background.