Reservoir Simulation

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 K.FEKI

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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 Reservoir Simulation Model

Geological Model

History Matching

Reduce Operation Expenses Increase Recovery

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Prediction

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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 i-1

i

i+1

ΔY ΔX

ΔX K.FEKI

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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

K.FEKI 48 Khalid Aziz, Petroleum reservoir simulation

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 K.FEKI

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Fluid flow equations • • • •

Type of fluid in the reservoir  Incompressible Flow regimes  Slightly compressible Steady State flow Reservoir geometry  Compressible Unsteady State flow • Radial flow Number of flowing fluids in the reservoir • • • • •

Pseudo Steady State flow Linear flow Single Phase flow Spherical and Hemispherical 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) The IMPES procedure solves for pressure at the new time level using saturations 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

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Numerical Models  Black oil model  Depletion Compositional  Water Injection model  o  o    o  o   o o

Gas injectionoil towater increase Component: gasor maintain reservoir pressure MiscibleOil flooding as the injection gas goes into solution with oil Phase: water gas Carbon dioxide flooding, with the gas soluble in both oil and water Polymer and surfactant injection Thick reservoirs with a compositional gradient caused by gravity Component: Water oil surfactant alcohol Reservoirs with fluid compositions near the bubblepoint Phase: Agues oleic microemulsion High-pressure, high temperature reservoirs Natural-fracture reservoir modeling. Component: C1,C2, ….So2,H2S,N2,.. Phase: Oil water gas

Chemical model

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Reservoir simulators        

ECLIPSE GPRS SENSOR NEXUS UTCHEM Boast 3 COMET3 …

      

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Objective Accuracy Time Limitations User friendly Easy to integrate …

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Eclipse reservoir simulator • Commercial reservoir simulator for over 25 years

• • • •

Black-oil Compositional Thermal Streamline

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Eclipse reservoir simulator    

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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 K.FEKI

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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