ABSTRACT: Framework for Constructing Clastic Reservoir Simulation Models

Koenrad J. Weber, L. C. Van Geuns

Techniques to convert geological information into engineering models have made rapid progress during recent years. In fact, so much is being published on the subject of reservoir characterization that is it timely to provide a framework for modeling as a function of reservoir type and heterogeneities.

The development geologist has to play an active role in data gathering in cooperation with the other disciplines. Early identification of major characteristics influencing fluid flow is required to design optimal data gathering schemes. Already at this stage, good communication between geologists and engineers is essential as well as replacing jargon with practical descriptive terminology.

Every modeling effort is aimed at specific purposes, which, in turn, determine the required degree of detail. In this context, the range of applicability of the various modeling approaches is reviewed. Much depends on the data density relative to reservoir architecture. Schemes indicate the chance of reliable deterministic correlation, and when to turn to alternative solutions such as probabilistic modeling. A database of sand-body geometries for each facies is a basic requirement.

The heterogeneities are treated as a nested system best approached from small to large. This stepwise upscaling to grid-block-size properties with appropriate averaging procedures is demonstrated with a few examples. Verification of the accuracy of the modeling and averaging procedures through timely well test analysis is considered crucial to ensure realistic results.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990