reservoir simulation

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Reservoir Simulation

Khaled FEKI

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THE CHALLENGE OF RESERVOIR SIMULATION …

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DYNAMIC RESERVOIR SIMULATION

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Incentives for running a flow 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 simulator

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Reservoir simulation model

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Reservoir simulation model

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Main modeled phenomena

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Definitions

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Types of models

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Types of simulators

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Types of simulators

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Black Oil model

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NUMERICAL MODELS: DISCRETIZATION

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Reservoir Simulation PLANNING

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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 ExpensesIncrease Recovery

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Problem definition

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Data review

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Main Types of Data

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Study approach

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Study approach

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GRID TYPES

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GRID TYPES

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Sugar box geometry

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Sugar box geometry

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Corner point geometry

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Reservoir description : PROPERTIES

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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+1i-1

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Block Identification and Ordering

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Block Identification and Ordering

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

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GRID SIZE SELECTION

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ACTIVE and DEAD CELLS

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GEOLOGICAL CONSTRAINTS

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CHOICE OF VERTICAL DISCRETIZATION

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Using LGR to model gas coning

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Block-centered grid

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Block-centered grid

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Block-centered grid

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Dip or fault ?

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CPG grid intercell flow

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Fault description in CPG grid

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Example of CPG reservoir model

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Fault description in CPG grid

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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

Khalid Aziz, Petroleum reservoir simulationK.FEKI

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Rock properties: Main parameters

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Rock properties: Net thickness and porosity

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Rock properties: Compressibility

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Rock properties: Compressibility

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Horizontal & Vertical Permeability

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Horizontal Permeability

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Vertical Permeability

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History Matching

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History Matching

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History Matching

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FIRST STEP - GENERAL FIELD MATCH - RUN 1

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FINAL STEP - GENERAL FIELD MATCH - RUN 3

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Predictions

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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• Large number of non-linear equations

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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 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 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

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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

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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 Open-ECLIPSE Developer's Kit

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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Grid definition: Quiz

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Reservoir layering: Quiz

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Rock properties: Main parameters

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Thank You!

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