--> --> Abstract: Horizontal Drilling Program, Stevens A1-A2 Sands, Northwest Stevens Area, Naval Petroleum Reserve No. 1, San Joaquin Basin, California, by J. B. Conard; #90945 (1997).

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Abstract: Horizontal Drilling Program, Stevens A1-A2 Sands, Northwest Stevens Area, Naval Petroleum Reserve No. 1, San Joaquin Basin, California

CONARD, JOANN B.

On behalf of owners DOE and CUSA, BPOI has kicked off a new horizontal infill drilling program in the A1-A2 Sands of the Northwest Stevens area, Naval Petroleum Reserve No. 1 (Sections 7R and 18R, T30S-R23E, San Joaquin Basin, California). The first two wells, drilled in 1996, proved successful, with IPs of 1077 and 539 BOPD. Program plans include drilling up to seven more horizontal wells as redrills of underutilized vertical wellbores.

Horizontal drilling technology has revitalized production in this mature pool, where thin oil band, updip gas injection and other factors make vertical drilling significantly less economic than horizontal drilling.

The hydrocarbon trap occurs where north-trending Stevens A1-A2 Sand channels cross the northwest-plunging Northwest Stevens/Tule Elk Anticline. The eastern channel edge forms an updip and lateral seal. Reservoir quality is excellent in these upper Miocene Monterey turbidites - with sand thickness up to 300 feet, porosity averaging 18%, and permeability averaging 102 md.

The A1-A2 oil band lies low on the flanks and nose of the anticline, between -8350 ft and -8500 ft TVSS in current elevation. In map view, it forms a horseshoe shape that opens to the east-southeast, against the eastern channel edge. The proposed 10-acre horizontal infill wells form a radial pattern to tap prospective fairways across the entire A1-A2 reservoir section. The horizontal leg of the wellbores occurs near the base of the 150' oil band, to: (1) maximize benefit from gravity drainage and updip gas injection pressure maintenance; and (2) minimize gas channeling from updip gas sources.

Search and Discovery Article #90945©1997 AAPG Pacific Section Meeting, Bakersfield, California