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Basin and Petroleum Systems Modelling: Applications for Conventional and Unconventional
Petroleum Exploration Risk and Resource
Assessments
By Dr Bjorn Wygrala Schlumberger
21-22 November 2013
5. Temperature and
Pressure
Education Days Moscow 2013
2
1. Opening Session: Industry Challenges and Opportunities
Conventional Petroleum Systems
2. Deepwater and Salt
3. Structural Complexity
4. Reservoir in Petroleum Systems Modeling
Theoretical Aspects
5. Temperature and Pressure
6. Petroleum Generation and Migration
Unconventional Petroleum Systems
7. Shale Gas/Oil
8. Gas Hydrates
9. Closing Session: Petroleum Systems Modeling in Context
3
Contents
Temperature
Processes, Models and Features
Temperature Pressure
Heat Flow Analysis
with Crustal Models Pore Pressure Analysis
with Compaction
Kinetics Petroleum Generation
Multicomponent
Reactions
PVT
Fluid Flow
Petroleum Migration
& Accumulation
Darcy Flow, Invasion
Percolation, Flowpath
and Hybrid Modeling;
all multi-component
Fluid Properties
Flash Iterations
Geomechanics Rock Stresses
Seal Failure and
Fault Properties
5
Oil and Gas Generation and Temperatures
Oil and Gas generation in source rocks is a function of
temperature and time!
In order to determine when and where oil and gas was
generated, we need to determine the temperatures in the
source rocks through geologic time.
This is commonly described as the Thermal History
6
Heat Transfer in Sedimentary Basins
water
basement
lithotype 3
lithotype 2
lithotype 1
basal heat flow bottom temperature (Tbot)
sediment water interface temperature (Tswi)
heat transfer
upper boundary
condition
lower boundary
condition
7
Heat Transfer Processes
The heat flow q [mW/m²] is defined as the amount of heat
energy [J] transferred per unit time [s] and per unit area [m²]*.
* After BATES and JACKSON (1983)
Heat can be transferred by:
Conduction – diffusive process whereby kinetic energy is transferred
by intermolecular collision. It is the most important
process in the crust and lithosphere
Convection – the heat energy is transported by motion of a fluid. Most
important process in the asthenosphere
Due to the temperature difference between the earth's surface and its hot
interior, heat flows to the surface.
Radiation – the heat energy is transported by electromagnetic
radiation. It is not important in subsurface heat flow.
8
Definitions: Thermal Conductivity
bulk= (1-f) rock + f water Arithmetic Average
bulk = rock(1-f)
waterf
Geometric Average
The thermal conductivity λ [W/mK] is the ability of a body to transfer heat
energy by conduction.
The bulk thermal conductivity bulk consists of 2 elements:
- the rock matrix thermal conductivity rock and
- the thermal conductivity of the pore fillings, e.g. water water.
Lithology λ [Js-1m-1K-1]
Sandstone 3.0
Shale 1.95
Water 0.65
Granite 2.4 – 3.8
Ice 2.2
salt 5.4 – 7.2
Thermal Conductivities
Rock Pore Fluids
10
1D Steady State Solution
11
Transient Effect – Rapid Sedimentation/Erosion
12
3D Heat Flow Equation
radwww QTvdivct
TcTgraddiv )(
Conduction Transient Term Convection Radioactive Source
Sediment 1
Sediment 2
Sediment 3
Sides:grad T = 0
Lower Boundary: Basal Heat Flow q
Water
Igneous Intrusions: Tint
λ c1, 1
λ c3, 3
2, 1c
Upper Boundary: Surface Temperature T
or Sediment Water Interface Temperature Ts
swi
Ts
Tswi
Ts
Fluid Flow
v
13 13
Thermal Perturbations due to Thermal Conductivity Differences Conceptual Model
Wygrala, 1989
higher thermal
conductivity (salt)
lower thermal
conductivity (all
other lithologies)
Heat Flow into
base of model
Temperature increase
above salt dome
Temperature decrease
below salt dome
isotherms show
temperature
perturbations
heat flow lines show heat
flow directions
Temperature at surface of model
Comments: The thermal conductivity contrast leads to increased heat flow through the salt dome which acts as a heat flow conduit. This results in:
- Temperatures: a relative increase above the salt dome, and a decrease below
- Heat flow: a relative increase within the salt dome, and a reduction on the sides of the salt dome
The only way to understand and predict possible anomalies is with a multi-dimensional thermal simulation. This is also essential in order to
calibrate wells on or in the vicinity of salt domes. Note that the model must extend to a larger distance below the base of the salt dome in order to
avoid inaccuracies in the thermal simulation.
14 14 Magri et al., 2008
Temperature increase
above salt dome
Temperature decrease
below salt dome
Thermal Perturbations due to Thermal Conductivity Differences Case Study
15 15
3D Petroleum Systems Model – Campos Basin
Salt domes in 3D model Surface heat flowin mW/m
2
75
58
37
thermal anomalies
caused by salt domes
Comments: Whether a thermal anomaly exists on the sediment surface and how strong it is depends mostly on:
- the size and geometry of the salt dome
- the depth of the top of the salt dome beneath the sediment surface
The only way to understand and predict possible anomalies is with a multi-dimensional thermal simulation.
16 16
3D Petroleum Systems Model – Controlling Parameters
W/m/K
mW/m3
low conductive
moderate conductive
high conductive
very high conductive
no radioactive
low radioactive
high radioactive
Basement20% Sandt & 40% Shale & 40% Carb
5% Sand & 80% Shale &15% Carb
ShaleMarlSaltSandstone
50% Sand & 40% Shale &10% Carb25% Sand & 60% Shale &15% Carb
Lithology
Thermal Conductivity (vertical)
Radioactive Heat Production
17
Boundary Conditions in Sedimentary Basins
water
basement
lithotype 3
lithotype 2
lithotype 1
igneous intrusion
basal heat flow bottom temperature (Tbot)
fluid flow
grad T = 0
grad T = 0
Tint
sediment water interface temperature (Tswi)
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a) At the time of intrusion b) After 10000 years
d) After 50000 yearsc) After 5000 years
50 Co 50 C
o
50 Co
50 Co
100 Co
100 Co
150 Co
150 Co
150 Co
648 Co
1000 Co
180 Co347 C
o
100 Co
100 Co
Magmatic Intrusions - Example
19
Heat Transfer in Sedimentary Basins
water
basement
lithotype 3
lithotype 2
lithotype 1
basal heat flow bottom temperature (Tbot)
sediment water interface temperature (Tswi)
heat transfer
upper boundary
condition
lower boundary
condition
20
Climate Change During Earth's History
540 mybp present
1.25 mybp present
Surface
Temperature (Northern Germany)
Global
Mean
21
Surface temperature for Northern Europe at 70 degrees latitude
Surface Temperatures
22
Water depth vs. Temperature
Depth profiles of bottom water temperatures for several
transects in the Northwest Atlantic Ocean margin.
From: POELCHAU et al. 1997
23
Heat Transfer in Sedimentary Basins
water
basement
lithotype 3
lithotype 2
lithotype 1
basal heat flow bottom temperature (Tbot)
sediment water interface temperature (Tswi)
heat transfer
upper boundary
condition
lower boundary
condition
24
Typical heat flows of sedimentary basins
From: ALLEN & ALLEN (1992)
25
Lower Boundary Conditions
Crust
Upper Mantle
Sediments
Basement
Base Temperature 1333 0 C
Basal Heat Flow
Stretching model
26
Crustal Stretching Model
The McKENZIE model (extensional basins)
27
Burial History Diagrammes
TIMED
EP
TH
?Hiatus
Sedim
entation
Erosion
Layer 1
Layer 2
Sedimentation: a time interval during which the increase in depth is known at
every point of time.
Erosion: a time interval during which changes in depth are only known if the
amount of erosion is known and thus the depth can be reconstructed.
Hiatus: a time interval during which depth is not changing; but it is only known if
erosion is known or can be excluded.
28
Burial history Plot with Temperature History
Screenshot PM 8.0
Example of burial history given by the data of Mandal-Ekofisk Oilfield
(see Petroleum Systems Modeling exercises).
29
Summary: Heat Transfer in Sedimentary Basins
water
basement
lithotype 3
lithotype 2
lithotype 1
basal heat flow bottom temperature (Tbot)
sediment water interface temperature (Tswi)
heat transfer
upper boundary
condition
lower boundary
condition
30
Contents
Pressure
31
Overpressure
“Overpressure is the result of the inability of formation fluids to escape
at a rate which maintains equilibration with a column of formation water
which exists to the surface” Swarbrick 1994
NO
Compaction
Dewatering possible Pp <
Sandstone
Shale
overburden
No dewatering Pp >
seff=sz-Pp
Terzaghi’s law
overburden Compaction
32
ph…Hydrostatic Pressure k…Permeability
p…Pore Pressure v…Viscosity
pl…Lithostatic Pressure C…Compressibility
f…Porosity …Density
Lithostatic pressure potential
pl = (r-w) g h ( 1 - f )
Hydrostatic and Lithostatic Pressures
Hydrostatic pressure =
static water column
ph = w g h
Lithostatic pressure =
combined rock and
fluid column
Plith=Ph + Pl
De
pth
Pressure
33
Hydrostatic and Lithostatic Pressures
De
pth
Pressure
Pressure reversal
Shale pressure acts as
a guide to pressure in
adjacent reservoirs
Shale pressure not a guide to
reservoir pressure
34
Compaction
Porosity-Depth curves for sandstones and shales from various published sources.
From: Wygrala (1989)
35
Gulf of Mexico Model
Salt Domes
36
Salt Blocks
37
Lithologies
Salt
Sandstone
Shale
38
Compaction
44%
32%
26%
39
Overpressures
40
Pressures in a Thin Sandy Unit
30.68
30.69
30.42
30.76
ugradk
divv
Pressure differences in
sandstones are orders of
magnitudes smaller than
pressure differences in
shales
41
Hydraulic Head Pressure
42
Hydraulic Head driven Water Flow
43
Hydraulic Head driven Water Flow
44
Processes, Models and Features
Temperature Pressure
Heat Flow Analysis
with Crustal Models Pore Pressure Analysis
with Compaction
Kinetics Petroleum Generation
Multicomponent
Reactions
PVT
Fluid Flow
Petroleum Migration
& Accumulation
Darcy Flow, Invasion
Percolation, Flowpath
and Hybrid Modeling;
all multi-component
Fluid Properties
Flash Iterations
Geomechanics Rock Stresses
Seal Failure and
Fault Properties