Eocene Wilcox gas reserves are growing in far South Texas.
Tesoro Petroleum Corp., San Antonio, has confirmed Bob West field in Starr County near the Mexican border and is drilling several other wells in adjacent counties.
Tesoro's latest completion is 2 Guerra, confirmation well in Bob West field. The field is east of the Falcon Reservoir portion of the Rio Grande River.
Drilled to 17,290 ft, it flowed 5.009 MMcfd of gas through a 12/64 in. choke with 6,080 psi flowing tubing pressure from Lower Wilcox perforations at 11,850-911 ft. Dual completion is being considered, said Kenneth Durham, Tesoro vice-president of exploration.
The well is a southeast offset to Tesoro's 1 Guerra discovery, completed in June 1990 for calculated absolute open flow (CAOF) potentials of 22 MMcfd and 51 MMcfd from two Wilcox zones other than those expected to produce in 2 Guerra.
The discovery well flowed 6.133 MMcfd of gas through a 12/64 in. choke with 6,334 psi flowing tubing pressure from perforations at 10,340-422 ft. And it flowed 6.075 MMcfd of gas through a 12/64 in. choke with 7,130 psi flowing tubing pressure from perforations at 10,654-684 ft.
Tesoro is completing 1 USA-Guerra, drilled to 13,415 ft northeast of the discovery well, and is drilling 3 Guerra, projected to 15,160 ft, farther southeast of the discovery well.
Gas production began Mar. 26 on the spot market from the discovery well, 31/2 miles north of Chapeno and 3 miles north-northeast of Middle Wilcox gas production in Falcon Dam field.
Production is about 12 MMcfd from the discovery well through a 10 in., 8 mile line Tesoro laid to an existing Tejas Gas Corp. pipeline system. Tesoro hopes to have the 2 Guerra and 1 USA-Guerra hooked up in 4-6 weeks.
The wells are on a farmout from Enercorp Resources Inc., Houston. All are directionally drilled except the discovery well.
MORE EXPLORATION
Tesoro is drilling for Wilcox gas in other areas of South Texas.
It completed 2 Pena in Alworth field of Zapata County, 25 miles northeast of Bob West field.
CAOF at the 2 Pena, 5 miles northwest of Guerra, is 110 MMcfd of gas.
The well flowed 4.873 MMcfd of gas through a 12/64 in. choke with 5,340 psi flowing tubing pressure from Upper Wilcox (Hinnant) sand perforations at 9,756-9,834 ft. Total depth is 10,000 ft. Tesoro holds 77.45% until payout.
This well and 1 Pena, an earlier Hinnant completion, are on shallow rights acquired from Tom Brown Inc., Midland, Tex.
About 15 miles southeast of Bob West field, Tesoro is drilling 1 Texaco Fee, a 100% Tesoro owned wildcat in Starr County. It is permitted to 19,000 ft or Upper Wilcox on a postulated large structure.
Site is 4 miles northwest of Roma and 1 mile east of West Roma field, where one well operated by Coastal Oil & Gas Corp. produces gas from Eocene Queen City 5,700 ft sand.
Tesoro was unsuccessful at 1 Vela in Northeast Lopeno field in Zapata County, north of Bob West field. The well, drilled to 8,691 ft, found a depleted shallow zone.
South Texas exploratory and development drilling hiked Tesoro's gas reserves in the year ended Sept. 30, 1990, to 11.1 bcf of gas from 600 MMcf.
Tesoro plans to drill about nine South Texas exploratory and development wells during 1991.
Copyright 1991 Oil & Gas Journal. All Rights Reserved.