Abstract

When conducting a reservoir simulation study, the simulation engineer should recognize not only the accuracy and applicability of the data input, but the simulator as well. This paper discusses grid orientation, time-step size, and omega effects on the accuracy and speed of the calculations for a reservoir depletion study of the Pembina Keystone Belly River M Pool. Also of interest in this study was the usefulness of a fence diagram in helping to understand the producing characteristics of some of the wells in the field. The method of history matching is also discussed.

As there is no unique set of reservoir parameters which produce a history match, it is important that the simulation engineer describe in the report both the reservoir parameters required to achieve a history match, and to what degree these parameters were adjusted from the core, log, and laboratory data used to initialize the model. This paper outlines the detail of presentation required to describe thoroughly the adjustments needed to achieve a history match for the Pembina Keystone Belly River M Pool.

Introduction

Reservoir simulation models are powerful tools for evaluating field development potential. Development schemes involving enormous amounts of capital are recommended based on computer output from mathematical models. It is therefore imperative that the simulation engineer understands not only basic reservoir engineering, but also the accuracy and applicability of the mathematical equations in the model which describe the physical processes active in the reservoir. Also, since a reservoir simulation study is so detailed and intricate, it is difficult for both management and other working interest owners to evaluate the technical aspects of the study. Therefore, the onus is on the simulation engineer to ensure technical validity and to provide the working interest owners with as much information about the study as is reasonably possible.

The objectives of this paper are:

  • to illustrate how to evaluate the effects grid orientation, time-step size, and mathematical solution technique have on the results computed by the simulator,

  • to suggest methods of data presentation which describe the adjustments to the core, log, and laboratory data needed to achieve a history match, and

  • to provide some reservoir and development information on the Pembina Keystone Belly River M Pool.

These objectives will be accomplished within the framework of a discussion of a reservoir simulation study of the Pembina Keystone Belly River M Pool. The Pembina Belly River M field history and reservoir description will be presented briefly, followed by the steps involved in model initialization, history matching and performance predictions. Common simulation detail such as a cross-sectional model for generation of pseudo relative permeability curves will be noted, but less common aspects of the study, such as time-step size optimization and minimization of computer execution time will be discussed more thoroughly.

Historical Background

The Pembina Keystone Belly River M Pool was discovered in 1962.

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