BATER, WILLIAM, and CATHERINE A. RIGSBY, California State University, Long Beach, CA

ABSTRACT: Subsurface Structural Investigation of a Portion of the Southwestern Section of the Long Beach Oil Field

The Long Beach oil field is one of the several en echelon faulted anticlines associated with Newport-Inglewood structure. The field has been a prolific producer of oil for more than 70 yr. As production diminishes, secondary and tertiary recovery will be required for further exploitation. This study delineates the subsurface structures of a portion of the Long Beach oil field and related newly mapped structures to current theories on the regional tectonics of the Los Angeles basin. This detailed reevaluation of the field provides a much needed framework for the implementation of secondary and tertiary recovery techniques.

The study area is located south of Spring Street and between California and Orange avenues in the city of Long Beach. Subsurface structures in this area are delineated and plotted on structure contour maps and cross sections using old oil field data, open trench studies, and a review of data from a shallow surface investigation.

The Long Beach oil field is bisected by two major strike-slip faults (the Cherry Hill fault and the Signal Hill faults) that define an anticline. Movement along the faults is interpreted as simple wrench faulting along the Newport-Inglewood trend with vertical faulting at depth and flower structures in the near surface. Cross faulting is inferred, but sparse data make confirmation difficult. Because of the geological and economic importance of this site, further study is essential. A planned geophysical study will complete the investigation and add confidence to existing interpretations.

AAPG Search and Discovery Article #90992©1993 AAPG Pacific Section Meeting, Long Beach, California, May 5-7, 1993.