Reservoir Simulation Pre and Post-Processing
Authors: Thomas L.K. , Sandoval R.K. , Evans C.E. , Dixon T.N. , Reist R.D. 
Published: December 2007

This paper describes the development of a general purpose system for pre and post-processing reservoir simulator data. This system was designed by Reservoir Simulation engineers with years of experience and is designed to assist engineers when modifying simulation data and performing history matching. The software and interface for most of the system were written in C++ and are object-oriented.

Introduction

Productivity tools for reservoir simulation are extremely important, especially today as the number of grid blocks used in major field studies may reach into the hundreds of thousands. The ability to intelligently make flow unit changes based on ready access to all pertinent data is a necessity in history matching.

Specific features in this software include display of corner-point-geometry grid data with local grid refinement, faults, PVT data, relative permeability, multi-phase flow data, log data, well trajectories, rate-time data, tracer maps, etc. History match plots of measured and calculated pressures, wellbore pressures, RFT, PLT, GOR, WOR, API gravity, etc. versus time are displayed.

These tools enable the engineer to graphically manipulate data by class, groupings or individual values. This software also enables the user to set cell properties by defining a mathematical expression containing other properties as variables. Drag-and-drop is used in key areas to facilitate creating new objects and for copying data. The ability to display multiple images of well performance and reservoir behavior allows the engineer to history match large scale simulator models in a timely manner.

Pre-Processing

CSim is the simulation pre-processor developed for use with Sensor. It allows the engineer to defme wells, platforms, separators, cell properties, schedule data, PVT data, relative permeability data, wellbore hydraulics, formation compaction and history data. CSim supports both rectangular and corner-point grids.

Data entry for cell properties can be performed by entering one value at a time, by dragging the cursor over cells, by circling cells or through mathematics. The Cell Math option allows the engineer to calculate cell property values. The mathematical expression can contain ether cell properties or (i, j, k) location as variables. The mathematical expression can be applied to the entire model, a layer or slice, by region number or rock type and by location relative to the fluid contacts. Cell Math supports standard functions and the ternary operator, thereby allowing the user to write formulas containing if-then-else logic.

Mathematical operations include the permeability from k- relationships, residual oil and connate water saturations from facies type and porosity, and porosity from porosity-impedance relationships.

The main window displays an image of a color-filled grid for a layer or slice. Platforms, separators, wells and wellbores are superimposed on the image. CSim takes advantage of graphic images whenever applicable to enhance usability. For example platforms, separators and wells may be selected from the screen. Other graphic capabilities include dragging of data points on plots when making adjustments and graphical editing of grid lines.

Drag and drop is used for creating objects by dropping them on an appropriate location or for deleting objects by dropping them onto the trash can. Each data entry screen reflects the data which is being entered, manipulations which the user may wish to perform on the data and the relationship between the data and objects defined in the model. All relationships between data are known by the program and appropriate actions are taken as the model is adjusted. For example, if a well is deleted, all history data and schedule data associated with the well are also deleted.

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