Geological Application in E.O.R.--A Synergistic Approach

William T. Long, George F. Hepler

A joint effort by both geologists and engineers is essential to ensure the successful development of an enhanced oil recovery (E.O.R.) project. Constant interaction among the reservoir engineer, petrophysical engineer, and geologist is needed in formulating a reservoir model and monitoring the actual performance of the project. Two case studies demonstrate the cooperative work by engineers and geologists to accurately describe a reservoir targeted for, or undergoing steam-enhanced oil recovery. To provide an accurate reservoir description, variations in reservoir quality and associated geometry were evaluated from conventional cores, computer-generated cross sections and isopach maps of various petrophysical parameters. The engineers provided the catalyst for study implem ntation.

A principle E.O.R. candidate in the southeastern San Joaquin basin is the lower Pliocene Etchegoin Formation, a progradational shoreface deposit and upper Miocene Chanac Formation, an associated coastal flood plain or distal alluvial-fan deposit. Determining reservoir facies distribution, texture, composition, and pore fluid salinity pose a significant challenge when generating a geologic reservoir model. The model suggests a preferred orientation for injected fluid movement.

In the eastern Los Angeles basin, the Anaheim reservoir (lower Pliocene Fernando) is a complex system of interfingering submarine fan channels composed of irregular lenses of conglomerate (clast supported) with a fine-grained matrix, permeable sands and impermeable silts. Parameters were derived in order to differentiate conglomerates and sands, allowing adequate characterization of the Anaheim reservoir for thermal enhancement.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.