FISHBURN, M. D., U.S. Department of Energy, Elk Hills, Tupman, CA

ABSTRACT: Future Deep Exploration Potential at Elk Hills, Kern County, California

Naval Petroleum Reserve 1 (Elk Hills) is located in the southwestern part of the San Joaquin Valley, one of the most prolific producing areas of the United States. Although the basin is reaching a mature state of development in the shallower zones, the deeper zones have only been penetrated in scattered areas, and little is known of their overall geologic framework or diagenetic history.

Three deep tests have been drilled at Elk Hills since 1976. Significant achievements were obtained from two: 934-29R and 987-25R. Well 934-29R bottomed in Cretaceous sediments at 24,426 ft, and well 987-25R topped low-grade metamorphic basement complex at 18,761 ft after penetrating over 800 ft of salt.

Cores and tests from these deep wells indicate that good potential for hydrocarbon exists below the Oligocene, and that hydrocarbons are being generated much deeper than previously thought. Higher than normal pressures at these depths enhance the opportunity to find large reserves. Vugular porosity encountered in rocks at 17,400 ft and at total depth in well 934-29R is an interesting phenomenon that may point to unusual diagenetic conditions not expected under deep burial conditions. A redrill of well 934-29R in 1993 will test the Oceanic sand at a better structural position. The zone tested condensate, gas, and water from a drill-stem test in the original hole at 17,400 ft. A commercial completion at this depth at Elk Hills will lead to additional deep tests in the reserve and may ge erate interest throughout the entire southern San Joaquin Valley for deeper plays by other oil companies.

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