Methods for Recovering More Oil from Known Fields: ABSTRACT

Waterflooding is the dominant fluid injection method used to recover secondary oil. It is economically attractive but leaves in the ground a large fraction (~ 50%) of the oil originally found. In the United States, for more than 30 years, research has been active in developing improved methods which are capable of producing a substantial part of the oil not recoverable by waterflooding (tertiary oil). The methods are usable in the secondary mode (instead of waterflooding) or in the tertiary mode (after waterflooding or natural water drive). Many methods are involved; most of them use water as a major injection constituent. The most promising methods for enhanced oil rcovery (EOR) involve either miscible displacement or thermal means to free the hard-to-recover oil. Althou h more than 400 field projects have been started with about 226 now (1-1-80) active in the U.S., and about 100 projects outside the U.S. (predominantly thermal type in Venezuela and Canada), the commercial use is now limited nearly entirely to secondary mode applications. Prospects in the tertiary mode have demonstrated technical operability. The economic potential, however, is uncertain, being related to changing price-cost relations. A critical factor in the successful selection and operation of EOR applications is an understanding of the nature of the geologic makeup of subject reservoirs. Thus, the exploitation geologist is expected to contribute substantially to EOR activities. End_of_Article - Last_Page 930------------