The Alphabet Soup of IOR, EOR and AOR: Effective Communication Requires a Definition of Terms

Abstract

Abstract The purpose of this paper is to call attention to the need to establish a mutually acceptable definition of the terms Enhanced Oil Recovery (EOR) and Improved Oil Recovery (IOR). It is hoped that the SPE will take note of the need to define the terms and use them as guidelines in reviewing of manuscripts for publications and presentations at its worldwide SPE meetings. A workable definition of the terms is necessary not just for improved communication, but also for recoverable reserves, contract negotiations, Government incentives, taxation purposes, and regulatory authorities when looking at fiscal issues. To get the discussion started, the authors propose workable definitions of the IOR and EOR terms based largely on an informal survey within the SPE EOR/IOR Technical Interest Group (EOIO TIG). Historical Use of the EOR and the IOR Terms Historically, there was reasonable consensus about the meaning of the EOR term. It was believed to denote tertiary oil recovery processes, such as chemical, thermal and gas miscible processes, among others. The IOR term followed, but without definition and was frequently used interchangeably with EOR. The two terms have been used in a very casual way in many different languages since the 1950's, often as synonyms. All the early symposia organized by the SPE and the Department of Energy used the term EOR and were meant to cover the new and, at that time exciting methods such as steam flooding, carbon dioxide flooding and, the then emerging chemical recovery processes. The EOR term became tarnished when some projects failed due to technical or economic reasons. Conference and symposia organizers then started to use the term IOR with the vague notion that, expanding the domain of EOR would attract more attention and more participants at their conferences. A case in point is the biennial SPE/DOE Conference in Tulsa, Oklahoma. The change from EOR to IOR in the early 1990's was prompted by the belief that broadening the domain of the conference to something over and above the original scope of EOR would attract more attendees. From then on, most conferences and symposia used the IOR, or the IOR/EOR term. Only the venerable Oil and Gas Journal, known for its biennial coverage of the "Worldwide EOR Activity" held steadfastly with the original EOR term (Ref.1). Definition of Terms: Primary, Secondary and Tertiary Further discussion will be well served by a brief review of the "primary", "secondary" and "tertiary" terms. These terms are generally understood and accepted (although a formal definition of these terms does not exist, either). They reflect and describe the natural progression of oil production from its inception to the point where economic production is no longer feasible. The concepts are well illustrated by the Oil and Gas Journal (Fig.1), in its biennially published Worldwide Survey of EOR Activities.