Abstract: Temblor Formation Stratigraphy and Depositional Systems, NPR-2 and Elk Hills Areas, Kern Co., California

MILLIKEN, MARK, Rocky Mountain Oilfield Testing, Casper, WY; TOR NILSEN, Consulting Geologist, San Carlos, CA

Deep marine turbidite sandstones of the upper Oligocene and lower Miocene Temblor Formation form gas and gas condensate reservoirs near the northern boundary of NPR-2 in the Elk Hills, Asphalto, Railroad Gap, and NE McKittrick fields of the western San Joaquin Valley. The producing intervals include sandstones and shales of the upper Santos and Carneros Members. Cumulative (1997) Elk Hills production was 2300 MBO and 8300 MMCF. Temblor production (primarily Carneros) for the adjacent Railroad Gap and Asphalto fields combined (1990) was 6000 MBO and 110,000 MMCF.The Carneros Member consists of four principal sandstone bodies, First through Fourth. Each sandstone body is a separate lowstand submarine fan system derived from erosion of both uplifted basement rocks and marginal nonmarine and shallow marine facies of the Temblor Formation sourced in the southern Diablo Range. Hydrocarbon traps are in northwest-trending, asymmetrical, en-echelon anticlines. These structures may be fault-propagation folds related to deeper thrust faults.

Fan deposits of the Carneros Member include amalgamated beds of fine- to coarse-grained turbidite sandstones forming blocky log signatures. The sand bodies filled a topographic low, with only minor variations in thickness and grain size. Porosity is low, due to cementation by calcite and quartz. Fractures are common in cores. Where absent, the First Carneros sandstone was eroded by uplift that locally removed most, if not all, of the overlying Media Shale Member. This angular unconformity caused confusion in earlier reports with regard to fault interpretations. A paleo-topographic high, possibly located in the NPR-2 area, may have been the source of a submarine landslide found to be widespread at the base of the First Carneros sandstone.

AAPG Search and Discovery Article #90911©2000 AAPG Pacific Section and Western Region Society of Petroleum Engineers, Long Beach, California