Abstract

Naval Petroleum Reserve #1 (Elk Hills) is located in the southwestern San Joaquin basin in one of the most profilic oil producing areas in the United States. Although the basin is in a mature development stage, the presence of favorable structures and high-quality source rocks continue to make the deeper portions of the basin, specifically Elk Hills, an inviting exploration target. Of the three deep tests drilled by the United States Department of Energy since 1976, significant geologic results were achieved in two wells. Well 987–25R reached low-grade metamorphic rock at 18,761 feet after penetrating over 800 feet of salt below the Eocene Point of Rocks Sandstone. In well 934–29R, the deepest well in California, sedimentary rocks of Cretaceous age were encountered from 23,800 feet to total depth of 24,426 feet.

Well 934–29R penetrated several major sand units, most of which encountered significant gas shows. Minor amounts of gas with no water were produced below 22,000 feet. Production tests at 17,000 feet produced 46 degree API gravity oil. Geochemical analysis of cores and cuttings indicated that the potential for hydrocarbon generation exists throughout the well and is significant since the possibility of hydrocarbon production exists at a greater depth than previously expected.