COUNTRYMAN, ROBERT L., Chevron USA, Bakersfield, CA
Title: ABSTRACT: Influence of Geology on the Design and Maintenance of Steam-Assisted Thermal EOR Projects in the Southern San Joaquin Basin, California, USA
AAPG/SVG INTERNATIONAL CONGRESS/EXHIBITION
March 14-17, 1993
California, the fourth largest oil producing state and the largest steam assisted thermal EOR (SAT EOR) producing region in the United States, produced 350.7 MMBO in 1990. SAT EOR accounted for 180.8 MMBO (52%) of which 163.9 MMBO (91%) came from fields in the southern San Joaquin Valley. SAT EOR production began in California in 1960 and, over the past 30 years, geologic studies have proved crucial in all successful projects. Most project failures, either economic or technical, can be traced to a lack of adequate geologic input during either the initial design/implementation or subsequent reservoir management stages.
Reservoirs range from structurally and/or stratigraphically simple to highly complex. Detailed geologic study is essential to define the external shape of a target reservoir for subsequent engineering design. Further study of internal details of the reservoir can anticipate potential clay or sanding problems, identify possible internal fluid barriers, and catalog other reservoir inhomogeneities. After initial project implementation, a second geologic review is recommended to incorporate new well data and modify the original interpretation. Once on-line, continuous monitoring of the target reservoir for temperature variation and fluid movements is essential to maintain peak efficiencies, time adjustments to steam injection rates, and fine-tune reservoir performance. Although such reser oir management is primarily an engineering function, geologic input is critical to understanding internal reservoir inhomogeneities and barriers affecting fluid and heat movement.
Case studies from Kern River, Midway-Sunset, and Cymric fields provide examples of how proper geologic studies can reduce capital investment, increase recovery efficiency, and maximize profitability.
AAPG Search and Discovery Article #90988©1993 AAPG/SVG International Congress and Exhibition, Caracas, Venezuela, March 14-17, 1993.