1

Reservoir Simulation

Khaled FEKI

K.FEKI

2

THE CHALLENGE OF RESERVOIR SIMULATION …

K.FEKI

3

DYNAMIC RESERVOIR SIMULATION

K.FEKI

4

Incentives for running a flow simulation

K.FEKI

5

Computer Modeling

The reservoir model Fluid flow Equation within the reservoir The reservoir is modeled by subdividing the reservoir volume into an array, or grid, of smaller volume elements, which called: gridblock, cell, or node.

The well model Fluid flow that represents the extraction of fluids from

the reservoir or the injection of fluids into the reservoir

The well bore mode Fluid flow from the sand face to the surface

The surface model constraints associated with surface facilities, such as platform and separator limitations

K.FEKI

6

Reservoir simulator

K.FEKI

7

Reservoir simulation model

K.FEKI

8

Reservoir simulation model

K.FEKI

9

Main modeled phenomena

K.FEKI

10

Definitions

K.FEKI

11

Types of models

K.FEKI

12

Types of simulators

K.FEKI

13

Types of simulators

K.FEKI

14

Black Oil model

K.FEKI

15

NUMERICAL MODELS: DISCRETIZATION

K.FEKI

16

Reservoir Simulation PLANNING

K.FEKI

17

A question of Scale

K.FEKI

18

Prediction Future performance

History Matching

Prediction

Geological Model

Reservoir Simulation Model

Reduce Operation ExpensesIncrease Recovery

K.FEKI

19

Problem definition

K.FEKI

20

Data review

K.FEKI

21

Main Types of Data

K.FEKI

22

Study approach

K.FEKI

23

Study approach

K.FEKI

24

GRID TYPES

K.FEKI

25

GRID TYPES

K.FEKI

26

Sugar box geometry

K.FEKI

27

Sugar box geometry

K.FEKI

28

Corner point geometry

K.FEKI

29

Reservoir description : PROPERTIES

K.FEKI

30

Reservoir description : PROPERTIES

K.FEKI

31

Reservoir Discritization

Defination: the reservoir is described by a set of gridblocks (or gridpoints) whose properties, dimensions, boundaries, and locations in the reservoir are well defined.

Block centered grid Point distributed grid

ΔX

ΔY

i i+1i-1

ΔXK.FEKI

32

Block Identification and Ordering

K.FEKI

33

Block Identification and Ordering

• Natural ordering• Zebra ordering • Diagonal D2 ordering• Alternating diagonal D4 ordering• Cycle ordering• Cycle-2 ordering

K.FEKI

34

GRID SIZE SELECTION

K.FEKI

35

ACTIVE and DEAD CELLS

K.FEKI

36

GEOLOGICAL CONSTRAINTS

K.FEKI

37

CHOICE OF VERTICAL DISCRETIZATION

K.FEKI

38

Using LGR to model gas coning

K.FEKI

39

Block-centered grid

K.FEKI

40

Block-centered grid

K.FEKI

41

Block-centered grid

K.FEKI

42

Dip or fault ?

K.FEKI

43

CPG grid intercell flow

K.FEKI

44

Fault description in CPG grid

K.FEKI

45

Example of CPG reservoir model

K.FEKI

46

Fault description in CPG grid

K.FEKI

47

Reservoir layering: Use of log Correlation

K.FEKI

48

Upscaling

• Optimum level of and techniques for upscaling to minimize errors

Gurpinar, 2001

Khalid Aziz, Petroleum reservoir simulationK.FEKI

49

Rock properties: Main parameters

K.FEKI

50

Rock properties: Net thickness and porosity

K.FEKI

51

Rock properties: Compressibility

K.FEKI

52

Rock properties: Compressibility

K.FEKI

53

Horizontal & Vertical Permeability

K.FEKI

54

Horizontal Permeability

K.FEKI

55

Vertical Permeability

K.FEKI

56

History Matching

K.FEKI

57

History Matching

K.FEKI

58

History Matching

K.FEKI

59

FIRST STEP - GENERAL FIELD MATCH - RUN 1

K.FEKI

60

FINAL STEP - GENERAL FIELD MATCH - RUN 3

K.FEKI

61

Predictions

K.FEKI

62

Predictions

K.FEKI

63

Predictions

K.FEKI

64

Fluid flow equations

• Conservation laws– Conservation in mass

Assume: Isothermal condition complete and instantaneous phase equilibration in each cell

– Conservation in energy– Conservation in momentum

• Additional constraints• Wells and facilities• Large number of non-linear equations

K.FEKI

65

Fluid flow equations

• Type of fluid in the reservoir• Flow regimes• Reservoir geometry• Number of flowing fluids in the reservoir

Incompressible Slightly compressible Compressible Steady State flow Unsteady State flow Pseudo Steady State flow• Radial flow• Linear flow• Spherical and Hemispherical flow• Single Phase flow• Two phase flow• Three phase flow

K.FEKI

66

IN OUT

Reservoir SimulatorPressureSaturation

Newton-Raphson (IMPLICIT)all primary variables are calculated at the same time.

IMplicit Pressure Explicit Saturation (IMPES)The IMPES procedure solves for pressure at the new time level usingsaturations at the old time level, and then uses the pressures at the new time level to explicitly calculate saturations at the new time level

K.FEKI

67

Numerical Models

Black oil model Depletion Water Injectiono Component: oil water gaso Phase: Oil water gas

Gas injection to increase or maintain reservoir pressure Miscible flooding as the injection gas goes into solution with oil Carbon dioxide flooding, with the gas soluble in both oil and water Thick reservoirs with a compositional gradient caused by gravity Reservoirs with fluid compositions near the bubblepoint High-pressure, high temperature reservoirs Natural-fracture reservoir modeling.o Component: C1,C2, ….So2,H2S,N2,..o Phase: Oil water gas

Polymer and surfactant injectiono Component: Water oil surfactant alcoholo Phase: Agues oleic microemulsion

Compositional modelChemical model

K.FEKI

68

Reservoir simulators

ECLIPSE GPRS SENSOR NEXUS UTCHEM Boast 3 COMET3 …

Objective Accuracy Time Limitations User friendly Easy to integrate …

K.FEKI

69

• Commercial reservoir simulator for over 25 years

• Black-oil • Compositional • Thermal • Streamline

Eclipse reservoir simulator

K.FEKI

70

Eclipse reservoir simulator Local Grid Refinement Gas Lift Optimization Gas Field Operations Gas Calorific Value-Based Control Geomechanics Coalbed Methane Networks Reservoir Coupling Flux Boundary Environmental Traces Open-ECLIPSE Developer's Kit

Pseudo-Compositional EOR Foam EOR Polymer EOR Solvent EOR Surfactant Wellbore Friction Multisegmented Wells Unencoded Gradients Parallel ECLIPSE

K.FEKI

71

Grid definition : Example

K.FEKI

72

Grid definition: Quiz

K.FEKI

73

Reservoir layering: Quiz

K.FEKI

74

Rock properties: Main parameters

K.FEKI

75

Thank You!

K.FEKI