Basics of Reservoir Simulation

LIST OF FIGURES

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INTRODUCTION

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Prerequisites

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1. OVERVIEW – MINIMUM REQUIRED DATA INPUT

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1.1 The grid

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1.2 Petrophysics

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1.3 Fluid properties

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1.4 Soil properties

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1.5 Equilibration

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1.6 Well specification

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1.7 Dynamics

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1.8 Output

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1.9 Simple Eclipse data file contents

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A. Syntax

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B. Data file (“BASIC data input example”)

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A note on units

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2. THE RUNSPEC SECTION

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Grid dimension – keyword DIMENS

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Phases

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Unit system

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Start date

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Unified / Non-unified files (chapter 11)

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Data checking only

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Table dimensions

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Well data dimensions

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NSTACK (chapters 17-18)

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Aquifer specifications – AQUDIMS (chapter 14)

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Grid options (chapter 13)

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Rock compressibility options (chapter 6)

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Local Grid Refinement (chapter 15)

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3. STRUCTURED GRIDS (CORNER POINT GRIDS) (GRID SECTION)

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The Corner Point Grid

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Defining a corner point grid in Eclipse

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Moderately complex grids – FILL

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4. PETROPHYSICS (GRID SECTION)

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Average permeability

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Transmissibility

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Inactive cells

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5. FLUID PROPERTIES (PROPS SECTION)

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Tables in Eclipse

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Relative permeability and Capillary Pressure

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Two-phase curves (water – oil)

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Three-phase relative permeabilities

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PVT data

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Water

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Dead Oil

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Dry Gas

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Live Oil

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6. SOIL COMPRESSIBILITY (PROPS SECTION)

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7. INITIALISATION (SOLUTION SECTION)

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Datum depth

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Contacts

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The Nacc parameter – accuracy of initial fluids in place calculations

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Equilibrium – discussion – advanced issues

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8. TIME DEPENDENT INPUT DATA (SCHEDULE SECTION)

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8.1 WELL DEFINITIONS AND CONTROL

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Well Specification (WELSPECS keyword)

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Well Completions (COMPDAT keyword)

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Production / Injection data (Keywords WCONPROD / WCONINJE)

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Economic well constraints (keywords WECON, WECONINJ)

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Other often used Well control keywords

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8.2 TIME STEPPING

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Order of actions

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8.3 CONVERGENCE CONTROL I (KEYWORD TUNING)

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9. REGIONS

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10. SIMPLIFIED INPUT AND MODIFICATION OF ECLIPSE ARRAYS

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BOX

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EQUALS

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ADD, MULTIPLY

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COPY

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COPYBOX

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11. ECLIPSE OUTPUT, FORMATS AND FILES

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File names

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Textual output

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The RPTXXX keywords

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Time dependent vectors – SUMMARY data

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Restart data and restart files

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12. RESTARTING A SIMULATION

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The SKIPREST keyword

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13. FAULT MODELLING – NON-NEIGHBOUR CONNECTIONS

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The 7-point stencil

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The fault layout – non-neighbour connections

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Fault transmissibility multipliers

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Defining a fault manually – the ADDZCORN keyword

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14. AQUIFER MODELLING (GRID SECTION)

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Aquifer definition

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Aquifer connection to reservoir

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15. LOCAL GRID REFINEMENT

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15.2 LGR on an irregular volume – Amalgamation

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Figure 1.

Regular Cartesian Grid

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Figure 2.

Regular XY-Cartesian Grid

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Figure 3.

Irregular structured grid

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Figure 4.

Unstructured grid

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Figure 5.

Cell indices and coordinate indices in a structured grid

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Figure 6.

Three of the four cells sharing a coord line, and some corner points

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Figure 7.

Cross-section view of a fault in a corner point grid

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Figure 8.

A shaly layer modelled as a gap (non-grid) in a corner point grid

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Figure 9.

Discretisation notation

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Figure 10.

Typical two-phase relative permeability curves

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Figure 11.

Volume factor and viscosity, dead oil (from example PVDO table)

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Figure 12.

Volume factor and viscosity for dry gas (from example PVDG table)

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Figure 13.

Variation of live oil volume factor, below bubble point and two branches

above (from example PVTO table)

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Figure 14.

Pressure variation near well bore – without skin and with positive skin

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Figure 15.

The 7-point stencil schematic

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Figure 16.

Sand to sand communication across a fault (vertical cross section)

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Figure 17.

Example XY-view of fault

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Figure 18.

Example use of continuity flags in ADDZCORN, left hand x-direction

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Figure 19.

Examples of use of combinations of cell index and zeros to move ind. corners

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Figure 20.

Examples of use of inactive cells to define aquifers (grid viewed from above)

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Figure 21.

Gas cone near a horizontal well, fine grid, vertical cross section

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Figure 22.

As figure 21, but on a coarse grid

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Figure 23.

Extending resolution of fine cells non-uniformly, XY-view

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Figure 24.

Example where one cell in original grid has been replaced with an LGR

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Figure 25.

Example LGR on irregular area (XY view)

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Figure 26.

A horizontal well on a standard grid (XY view)

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Figure 27.

As Figure 26, but using LGR near the well

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Figure 28.

Actual well path (grey) and grid approximation (black) (XY-view)

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Figure 29.

Natural ordering of a 4 x 3 x 2 grid

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Figure 30.

Coefficient matrix for a 4 x 3 x 2 grid (x means “nonzero element”)

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Figure 31.

Solving a nonlinear problem with the Newton-Raphson method

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Figure 32.

Labelling the seven diagonals in a 7-diagonal matrix

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Figure 33.

A grid with ZYX ordering

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Figure 34.

System structure for grid in Figure 33

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Figure 35.

Grid as in Figure 33, but with fault

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Figure 36.

System structure for faulted grid

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