Abstract

The decision making process related to the recovery strategy during the development of a petroleum field is very complex because it involves a great amount of money and parameters and it is necessary to consider the risk associated with geological, economical and technological uncertainties.

An adequate choice of production strategy provides a satisfactory reservoir performance, improving the field recovery. Therefore, it is very important to have methodologies (1) to improve the quality of the results and (2) to accelerate the process.

This paper shows some optimization procedures applied to production strategy planning process. The procedure was developed for several types of reservoirs and includes producer and injector vertical wells. Furthermore, it uses reservoir simulation to improve the reliability of the prediction of production performance. The procedure was developed in a flexible way, allowing the application to different situations. The results of some of these cases are presented.

The methodology proposed does not provide a unique solution. It presents a set of alternatives that are analyzed in the decision making process for the planning of a recovery strategy, considering the objectives of the project.

Introduction

The planning of strategies for the development and management of petroleum reservoirs is one of the most important activities in reservoir engineering. The strategies are elaborated considering a previously defined objective, regarding physical, operating and economic restrictions. An adequate recovery strategy depends mainly on the geological characteristics of the reservoir and on the operational schedule defined for the field. A high number of parameters influence the decision making process. Therefore, it is not feasible to evaluate all possible combinations. It is necessary to evaluate the most important parameters related to the problem and develop an approach for this problem in order to achieve satisfactory solutions.

Petroleum reservoirs are very complex and there are great difficulties involved in proposing correct reservoir models. The use of numerical simulation provides a preview for the reservoir performance, considering a geological model previously prepared from several parameters obtained during the field appraisal. The use of numerical simulation is appropriated for the planning of strategies for the development of petroleum fields. It requires more time, however, it makes the process more reliable, leading to better results.

This work proposes a methodology containing an optimization procedure based on reservoir simulation that evaluates both individual well and field performance and the objective-function chosen was Net Present Value (NPV). The methodology helps managers to make decisions that lead to an adequate recovery for the reservoirs and to maximize profits and minimize risks associated to the investments. An example is presented where water injection strategy planning is performed with numerical simulation of an Atlantic offshore field in Campos Basin - Brazil. It can be shown the importance of reservoir simulation in the optimization of recovery strategies for petroleum reservoirs including water injection.

Literature Review

The planning of adequate recovery strategies for petroleum reservoirs has a great economic importance and several studies have been realized for the development of procedures applied to this problem.

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