Reservoir Simulation

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Reservoir Simulation

Khaled FEKI

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DYNAMIC RESERVOIR SIMULATION

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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

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Reservoir simulation model

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Main modeled phenomena

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Types of models

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Types of simulators

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NUMERICAL MODELS: DISCRETIZATION

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A question of Scale

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Prediction Future performance

History Matching

Prediction

Geological Model

Reservoir Simulation Model

Reduce Operation Expenses

Increase Recovery

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Problem definition

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Main Types of Data

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Study approach

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GRID TYPES

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Sugar box geometry

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Reservoir description : PROPERTIES

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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+1 i-1 ΔX K.FEKI

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Block Identification and Ordering

• Natural ordering

• Zebra ordering

• Diagonal D2 ordering

• Alternating diagonal

D4 ordering

• Cycle ordering

• Cycle-2 ordering

K.FEKI

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ACTIVE and DEAD CELLS

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CHOICE OF VERTICAL DISCRETIZATION

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Block-centered grid

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Block-centered grid

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CPG grid intercell flow

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Example of CPG reservoir model

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Reservoir layering: Use of log Correlation

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Upscaling

• Optimum

level

of

and

techniques

for upscaling to

minimize errors

Gurpinar, 2001

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Rock properties: Main parameters

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Rock properties: Compressibility

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Horizontal & Vertical Permeability

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Vertical Permeability

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History Matching

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FIRST STEP - GENERAL FIELD MATCH - RUN 1

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Predictions

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Predictions

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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

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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

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Pseudo Steady State flow

• Radial flow

• Linear flow

• Spherical and Hemispherical flow

• Single Phase flow

• Two phase flow

• Three phase flow

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IN OUT

Reservoir Simulator

Pressure Saturation

Newton-Raphson (IMPLICIT)

all primary variables are calculated at the same time.

IMplicit Pressure Explicit Saturation (IMPES)

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Numerical Models

 Black oil model

 Depletion

 Water Injection

o Component: oil water gas o 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 injection

o Component: Water oil surfactant alcohol o Phase: Agues oleic microemulsion

Compositional model

Chemical model

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Reservoir simulators

 ECLIPSE

 GPRS

 SENSOR

 NEXUS

 UTCHEM

 Boast 3

 COMET3

 …

 Objective

 Accuracy

 Time

 Limitations

 User friendly

 Easy to integrate

 …

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• Commercial reservoir simulator for over 25 years

• Black-oil

• Compositional

• Thermal

• Streamline

Eclipse reservoir simulator

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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

Pseudo-Compositional

EOR Foam

EOR Polymer

EOR Solvent

EOR Surfactant

Wellbore Friction

Multisegmented Wells

Unencoded Gradients

Parallel ECLIPSE

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Grid definition : Example

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Reservoir layering: Quiz

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