--> Abstract: Geology and Production Characteristics of the 29R Structure, Elk Hills, Kern County, California, by J. L. McIntyre, S. A. Reid, and G. S. McJannet; #90992 (1993).

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McINTYRE, J. L., and S. A. REID, Bechtel Petroleum, Tupman, CA, and G. S. McJANNET, U.S. Department of Energy, Elk Hills, Tupman, CA

ABSTRACT: Geology and Production Characteristics of the 29R Structure, Elk Hills, Kern County, California

Several small Miocene reservoirs occur in association with the 29R structure at Elk Hills: upper Miocene 29R/24Z shales, 2B sand, and 24Z sand of the Elk Hills Shale Member of the Monterey Formation, and lower Miocene Carneros Sandstone and upper Santos Shale Members of the Temblor Formation. Ninety-six wells produce from these reservoirs, and twelve water injectors and one gas injector support production from the 24Z sand. Total cumulative oil production and remaining reserves through October 1992 are about 85 million bbl of oil and 115 million bbl of oil, respectively. Together these reservoirs encompass portions of 14 sections, an area of about 7 sq mi.

The 29R structure is a northwest-trending, asymmetric, doubly plunging anticline. Within the Monterey, and possibly the Temblor, the fold bifurcates along the western nose; the northern branch extends into the 24Z pool. Fold asymmetry implies that folding is related to thrust faulting rather than wrench faulting. The thrust fault, if present, must flatten or terminate below unfaulted younger Monterey zones on the more steeply dipping northern flank.

The geometry of the reservoirs is influenced by the timing of deposition with respect to structural growth. Tabular upper Santos, Carneros, and lower 29R shale reservoirs were deposited on a subsea basin floor of low relief. Lower 24Z and 2B sands were deposited during early structural growth in slight topographic lows. Increasing relief due to anticlinal growth resulted in more abrupt terminations of the upper 24Z and 2B sands and thickening of upper 29R and 24Z shales on the flanks.

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