THE SPE IMAGE LIBRARY SPE 18305

Engineering Control in Reservoir Simulation: Part I

18305

Saleri, N.G., and Toronyi, R.M., Chevron Geosciences Co.

SPE Members

Copyright 1988, Society of Petroleum Engineers

This paper was prepared for presentation at the 63rd Annual Technical Conference and Exhibition of the Society of Petroleum Engineersheld in Houston, TX, October 2-5, 1988.

This paper was selected for presentation by an SPE Program Committee following review of information contained in an abstract submitted by the author(s). Contents of the paper, as presented, have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material, as presented, does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Papers presented at SPE meetings are subject to publication review by Editorial Committees of the Society of Petroleum Engineers. Permission tocopy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. WritePublications Manager, SPE, P.O. Box 833836, Richardson, TX 75083-3836.

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ABSTRACT

This paper presents a broad critique of the current state of reservoir simulation and its applications with an emphasis on its three key shortcomings:(1) lack of established industry standards forsimulation (2) non-uniqueness, and (3) inherent uncertainties in reservoir modeling. Examples are discussed to demonstrate how these factors can and have led to misinterpretation and misuse of simulation results.

THE SPE IMAGE LIBRARY SPE 18305

INTRODUCTION

The objective of this paper is to initiate a critical self-evaluation by the industry on the use of simulation in reservoir management. During the last decade, reservoir simulation has gained increasing acceptance in this area; yet, its full utilization is stil constrained by several unresolved questions. In fact there is a prevalent skepticism in the industry regarding its role as a consistently reliable reservoir management tool.

Compounding the problem are common misperceptions in the industry regarding the limitations versus capabilities of simulation. Often it is criticized for not producing reliable results which are beyond its capacity (e.g.. ultimate recovery). This is an outcome of its being equated to a deterministic tool, e.g., a chemical process simulator. In reality, it is a probabilistic vehicle much like weather forecasting models. What further amplifies the industry's misgivings regarding simulation is the prevalence of uncontrolled and arbitrary practices in simulation with too little emphasis on engineering and geologic control.

Simulation can be a very valuable and effective tool. This, however, depends entirely on (a) its acceptance and implementation by the user community as a probabilistic tool with inherent uncertainties and (b) the exercise of stringent engineering and geologic control measures and a structured methodology in its utilization.

This pape is a step in the direction of the two principles noted above. It forms the first leg of a three-part series: (I) A Critique of Current Practices, (II) Methodology, and (III) Examples. Parts II and III are presented as an addendum to this paper. Part I presents a critique of the current state of simulation and its applicationswith an emphasis on three key shortcomings: (1) lack of established industry standards forsimulation, (2) non-uniqueness, and (3) inherent uncertainties in reservoir modeling.

Part II proposes a general methodology for conducting simulation studies. The methodology allows a systemati (as opposed to an uncontrolled) approach to model selection, construction, validation, and predictions thus reducing the potential for the commonly noted misuses. Included are steps for engineering and quality control.

Part III presents three examples of Chevron studies where the methodology has been successfully used.

THE SPE IMAGE LIBRARY SPE 18305

CRITIQUE OF CURRENT PRACTICES

The discussion will consist of four main topics:

1. Overview of literature

2. Current practices

3. Shortcomings of reservoir simulation 4. Misuses

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