Texaco Exploration & Production Inc. may have found the key to unlock North Shafter oil field in California's San Joaquin Valley. The company's perseverance paid off with completion of a horizontal well for initial production of 1,194 b/d of 26.5° gravity oil and 476 Mcfd of gas on a 34/64 in. choke with 300 psi flow pressure and 523 b/d of load water. TD is 10,204 ft.
The 3-3H Tulare, in 3-28s-25e, Kern County, is at the south end of the field.
The horizontal hole tapped 2,206 ft in Miocene McLure shale.
The next step toward completion was a frac job by Dowell using atypical, advanced technology developed at Texaco's Bellaire, Tex., lab.
The well's flow rate is expected to decline, then stabilize after about 30 days. Texaco owns 100% working interest in the well and plans more drilling that could add significant life to North Shafter field.
The section on which the horizontal well is located is the one on which Amoco discovered the field in December 1983. The 13,934 ft discovery well turned up oil shows in McLure shale topped at 7,380 ft. After Amoco deemed two wells noncommercial, a succession of operators owned them.
The discovery well remained the field's only producer until Texaco teamed with Texas Crude Energy Inc., Houston, in 1995. The result was completion of the 1-34 Tulare, in 34-27s-25e, a north offset to the discovery well. After frac it flowed at rates as high as 500 b/d before declining rapidly, but more wells were drilled.
San Joaquin Facilities Management, owner of the field's first two wells, ran a frac job on the 1-A Shafter in 1996. Through the end of the year, the two wells had produced 84,700 bbl of oil.
Eight wells in addition to the fast flowing new well are on production now, including six owned by Texaco/ Texas Crude and two operated by San Joaquin. Production from the Texaco/Texas Crude vertical wells averages 30-50 b/d of oil.
Copyright 1997 Oil & Gas Journal. All Rights Reserved.
