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)

18

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