Publications

Waterflooding is the dominant fluid injection method used to recover secondary oil. It is economically attractive but leaves in the ground a large fraction ( *L 50%) of the oil originally found. In the USA, for more than 30 years, research has been active in developing improved methods whicl are capable of producing some of the oil left 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 recovery (EOR) involve either miscible displacement or thermal means to free the hard-to-recover oil. Although more than 400 field projects have been started with about 225 now active in the USA, with an addition of about 100 projects outside US, predominantly thermal type, in Venezuela and Canada, the commercial use is now limited nearly entirely to secondary mode applications. Projects in the tertiary mode have demonstrated technicd operability. The economic potential, however, is uncertain, being related to changing price-cost conditions and the nature of the specific reservoirsanatomy (reservoir rock description).