The Kern River field in California currently produces over 100,000 bbl of heavy crude oil per day from several steam-drive projects. Conservatively, recoverable reserves of 600 million bbl remain as the prize of enhanced oil recovery techniques. Operating costs for steam-drive projects are high because for every three barrels of crude produced, one barrel is burned to generate the steam. To effectively operate such projects, geologic conditions of the reservoir must be thoroughly understood. Close coordination between the geologist and the engineer is needed to evaluate and follow steam-drive performance on a pattern-by-pattern basis. Detailed cross sections and isopach maps of the reservoir sands and their overlying

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heat capping shales are prepared by the geologist. Then, working with the engineer, correlations of reservoir heat patterns are made by matching actual temperature response and production trends within their geologic constraints. These geologic-engineering evaluations of existing projects have often pointed out the need for significant changes in steam-injection profiles, steam rates, and other operating conditions. The geologist has an important role to play not only in forward planning for steam-drive projects, but also in formulating operational plans and decisions throughout the life of the project.

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