SANDE, JEFFREY J., Shell Western E&P Inc., Bakersfield, CA

ABSTRACT: A Summary of Horizontal Wells Drilled by Shell Western E&P Inc. in Steeply Dipping Turbidite Sand Reservoirs, Midway Sunset Field, Kern County, California

The Kernridge Production Division of Shell Western E&P Inc. has drilled three successful short-radius horizontal wells in a mature steam drive in Midway Sunset Field, Kern County, California. The upper Miocene Sub-Hoyt E sands have been undergoing steam-drive development since 1978. A descending steam chest occupies more than half the average 400-ft gross E sand thickness. The horizontal wells have been drilled at the base of these sands, 10 ft above the oil-water contact. The horizontal wells should improve recovery efficiency, accelerate production, improve the oil-steam ratio, and therefore increase project profitability.

The E sand reservoir is comprised of moderately sorted, turbidite mid to upper submarine fan channel sands. The sands are massive to thin bedded, with diatomaceous shales interbedded throughout. Average depth to the oil water contact is 1350 ft. The sands dip at 45 degrees to the northeast. Oil gravity is 13 degrees API.

The horizontal wells have cost 2-3 times more than a vertical well. However, initial production after steam soak for the first two horizontal wells, whose average lateral length is 400 ft, has been 2-3 times greater than a vertical well. The third well has yielded 4 times greater production rates from a 700-ft lateral. Horizontal wells are a viable option for the ultimate development of the steam drive reservoirs in Midway Sunset field. A medium-radius horizontal well was planned in late 1992 for the E Sands, and studies by all engineering disciplines are underway to improve horizontal well technology and performance.

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