What Is Reservoir Engineering

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RESERVOIR ENGINEERING

What

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Reservoir Engineering?
P. L. ESSLEY. JR. ‘iEhtEER AIME I I SINCLAIR RESEARCH, INC. TULSA, OKIA.

Abstract
Reservoir engineering involves more than applied reservoir tnechanics. Tfw objective of engineering is optintization. To obtain optinumt profit jrotn a field the engineer or the engineering team must identify and define all individualreservoirs and their physical properties, deduce each reservoir’s performance, prevent drilling of utlnecessary wells, initiate operating controls at the proper time, and consider all important econontic factors, including income taxes. Early and accurate identification and definition of the reservoir systent is essential to effective ettgineering. Conventional geologic techniques seldom providesufficient data to identijy and define each individual reservoir; the engineer tnust suppletnent the geologic study with engineering data and tests to provide the necessary infortnation. Reservoir engineering is difficult; The most successful practitioner is usually the engineer who, through extensive efforts to understand the reservoir, tnanages to acquire a few more facts and thus needs fewerassutnptions.

Introduction Reservoir engineering has advanced rapidly during the last decade. The industry is drilling wells on wider spacing, unitizing earlier, and recovering a greater percentage of the oil in place. Techniques are better, tools ‘ are better, and background knowledge of reservoir conditions has been greatly”improved. In spite of these general advances, many reservoirs are beingOr[ inal manuscript recdved in Society of Petro Y eum Engineers office Aug. 8, 1964, Re. vised mnnusdtM received Nov. 2. Paper resented at 39th SPE Annual Fall Meeting k’ eld in Houston Oct. 11-14, 1964,

developed in an inetllcient manner, vital engineering consideratiorm often are neglected or ignored, and individual engineering efforts often are inferior to those of a decade ago. Reservoirengineers often disagree in their interpretation of a reservoir’s performance, It is not uncommon for two engineers to take exactly opposite positions before a state commission. Such disagreements understandably confuse and bewilder management, lawyers, state commission members and laymen. Can they be blamed if they question the technical competence of a professional group whose members cannotagree among themselves? There is considerable difference between the reservoir engineering practiced by different companies, The differences between good engineering and ineffective engineering generally involve only minor variations in fundamental knowledge but involve major differences in emphasis of what is important, Some companies or groups emphasize calculation procedures and reservoirmechanics, but pay little attention to reservoir geology. Others emphasize geology and make extensive efforts to identify individual reservoirs and deduce their performance during the development period or during the early operating period. They use reservoir engineering equations and calculation procedures’ primarily as tools to provide additional insight of a reservoir’s performance, Those utilizing thelatter approach generally are the most successful. The. differences in practice observed indicate that many individuals, including managers, field personnel, educators, scientists and reservoir engineers do not understand the full scope of reservoir engineering or how the reservoir engineer can be used

most effectively. A better understanding of the ba~c purpose of reservoir engineering and howit can be utilized most effective y should result in improved engineering. Reservoir Engineering — A Group Effort
The Purpose of Engineering The goal of engineering is optimization. The purpose of reservoir engineering is to provide the facts, information and knowledge necessary to control operations to obtain the maximum possible recovery from a reservoir at the least possible cost. Since a...