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Abstract: Improved Oil Recovery from a Mature Monterey Formation Sandstone Reservoir Using Low Cost Intermediate Radius Horizontal Producers at Elk Hills, Kern County, CA

OWENS, BRIAN, Occidental of Elk Hills, Inc., Tupman, CA; JANA MCINTYRE, Occidental of Elk Hills, Inc., Tupman, CA; MARK STARCHER, Occidental of Elk Hills, Inc., Tupman, CA; GLEN HONSTEIN, Drilltek, Bakersfield, CA 

A cross-functional team at Elk Hills implemented a profitable development strategy in a mature Monterey Formation sandstone reservoir that required a novel approach. The use of intermediate-radius (IR) horizontal wells re-drilled from shut-in vertical wells and completed with slotted liners enabled the development of incremental reserves. Success in this project has led to application of the IR horizontal re-entry technique in other Elk Hills reservoirs.

Since 1982, crestal gas injection has been employed to support oil production from the Northwest Stevens (NWS) A1-A2 reservoir. Oil recoveries have been high and by early 1998 declining oil production and a rising GOR made continued gas injection economically questionable despite an oil column of 100 to 150 feet. The design of the existing horizontal wells represented the prevailing completion strategy: medium-radius drilling with cemented and perforated liners. A quick, low cost solution was needed due to the impending blow-down. Intermediate-radius producers were pursued.

The first IR horizontal well was drilled in the NWS A1-A2 reservoir in October 1998. This well was placed about 50 feet above the oil-water contact and successfully completed with a 3 1/2" slotted liner. The well initially produced at 680 bopd, exceeding expectations. Ten IR well have been drilled in NWS including one dual horizontal. Seven of the wells were highly successful while one well had a high water cut and may be re-drilled. The performance of the new IR horizontals is similar to the medium-radius predecessors despite the lower reservoir pressure and reduced oil column.


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