G. Alan Petzet
Exploration Editor
Deep and not so deep exploration is under way in the southeastern Delaware and northwestern Val Verde basins in West Texas.
Northern Terrell County is seeing a good agenda of Permian Wolfcamp development drilling in spite of testy gas prices.
None of the present drilling appears to be targeted to Ouachita facies along the Marathon portion of the Ouachita Overthrust, although oil production from several of those fields has been respectable.
And a number of exploratory tests to 20,000 ft and deeper are under way or on tap in eastern Pecos County and Terrell County.
20,000 FT ACTION
Hunt Oil Co., Dallas, staked a deep wildcat 4 miles east of Gomez field in Pecos County. Hunt's 1 Tomahawk, 9 miles northeast of Fort Stockton, is projected to 25,000 ft.
Exxon Exploration Co. staked 13 Henry Wilbanks, a deeper pool wildcat in Gomez Ellenburger gas field 11 miles north of Fort Stockton. Projected depth is 22,500 ft. Ellenburger production in the area is from about 20,800 ft.
And Conoco Inc. spudded Oct. 8, 1991, at 1 Abilene Christian University, a planned 20,000 wildcat.
Presumably an Ellenburger test, this well is about 35 miles northeast of Sanderson, Tex.
Conoco's wildcat is about 3 miles northeast of McKay Creek field, discovered in 1979 along the Ouachita-Marathon overthrust belt. The field produces oil from Mississippian-Devonian age Caballos at about 6,000 ft.
Ellenburger, if productive, could contain methane with high carbon dioxide content as it does at other significant fields in the area.
PRICES, PENETRATION
Gas prices and the potential to improve penetration rates hold the keys to developing the gas field of northern Terrell County, says Riata Energy Co., Amarillo.
Riata operates gas wells in Pakenham, K M, K M West, K M '7,300,' Little Canyon, Leatherwood, and East University Block 34 fields.
The reservoirs are stratigraphic traps with as many as four Wolfcampian sections that shale out against the tilted leading edge of the Ouachita Overthrust Belt to the south.
El Paso Natural Gas Co. and Valero Transmission Co. purchase gas from the area where Riata has nine wells connected to pipelines. Valero's prices are to be about $1.40/MMBTU in January 1992 and perhaps $1.10-1.15/MMBTU in February, Riata said.
Riata hopes to drill as many as eight more Wolfcamp gas wells during 1992 and believes drilling costs can be reduced using air hammers. The 10,000 ft Wolfcamp wells cost about $900,000/well.
The company believes it has about 30 prospective locations for additional gas wells on its leases in the area.
CO2 POTENTIAL
Conoco and other operators could be looking to develop new CO2 potential and tap existing reserves in the area.
Some CO2 is being flared from large Brown-Bassett field.
Riata has about 35 MMcfd of total deliverability in three wells shut-in at Leatherwood (Devonian) field, and close to 70% of the stream would be CO2.
CO2 also could be a partial objective of deep Ellenburger exploration in the area. Aggregation of sufficient volumes might justify a pipeline northwestward to Permian basin oilfields for enhanced recovery projects.
Some Permian basin fields have been served by CO2 from gas processing/treatment plants, but CO2 from wells would be a more reliable source for EOR projects.
OVERTHRUST SUCCESSES
Ouachita rocks of the Caballos, Pennsylvanian-Mississippian Tesnus, and Lower Pennsylvanian Dimple formations have produced in only a few fields in south-eastern Pecos and northern Terrell counties.
Texas Railroad Commission figures show that the Caballos reservoir at McKay Creek field had produced 914,047 bbl of oil through Jan. 1, 1991, and produced 78,934 bbl of oil during 1990. Five wells were producing at yearend 1990.
The former Texas Pacific Oil Co. opened McKay Creek field in 1979 at the 1 Word. It pumped 211 b/d of oil from Caballos at 6,162-6,238 ft.
TRC figures show that one Caballos reservoir in Thistle field of Pecos County produced 1.02 million bbl from mid-1984 through Jan. 1, 1991, and had five wells producing at yearend 1990. The reservoir made 121,246 bbl during 1990.
Shell Western Exploration & Production Co. opened Caballos Novaculite oil production in Thistle field in 1984. The 1-4 Downie Ranch pumped 341 b/d of oil from 2,732-2,830 ft, Petroleum Information data show.
Shell's 2 Downie Ranch, a workover in the field, flowed 213 b/d of oil from the pay at 1,690-1,810 ft a year later. And in 1990, Shell's 304 Downie Ranch flowed 55 Mcfd of gas from Caballos B at 1,592-1,660 ft.
Farther west in southeast Pecos County, Overthrust zones have produced gas in Pinon, West Ranch, and Bitterweed fields. Tenneco opened Pinon field in 1983 with Dimple and Caballos completions. The 1 Green flowed 1.856 MMcfd of gas from Dimple at 3,672-3,774 ft, and the 2 Green flowed 4.015 MMcfd from Caballos at 4,839-4,954 ft.
Fina Oil & Chemical Co. now operates Pinon field.
J. Cleo Thompson opened Tesnus gas pay in 1989 in West Ranch field of Pecos County. The 2201 West Ranch flowed 428 Mcfd of gas from 4,126-4,412 ft.
Total depth is 5,770 ft.
Tenneco opened Caballos gas pay in Bitterweed field of Pecos County in 1988. Its 1-5 West Ranch flowed 4.221 MMcfd of gas from 4,980-5,194 ft.
OTHER DEVELOPMENTS
Development of Permian Wolfcamp gas reserves is proceeding in northern Terrell County.
Riata's 1 Mitchell, in Pakenham field, flowed 1.4 MMcfd of gas through a 14/64 in. choke with 2,205 psi flowing tubing pressure from perforations at 9,766-10,320 ft. CAOF is 5.8 MMcfd of gas.
Tenneco Oil Co. and Fina Oil & Chemical Co. originally permitted the well in 1988 as the 1 Big Horn Ridge. It was drilled to 19,653 ft and temporarily abandoned in early 1991, Petroleum Information reported.
Riata in 1987 completed the 1-59 Mitchell, for 1.138 MMcfd of gas from Wolfcamp perforations at 8,432-8,612 ft.
Amoco Production Co. opened Pakenham field in 1975. The RA Pakenham Ranch Co. Ltd. flowed 640 Mcfd of gas from Wolfcamp at 7,406-63 ft.
Hombre Oil & Gas Co., Midland, opened Wolfcamp gas pay in K M oil field in 1990. Its 1-R Mitchell flowed 1.609 MMcfd of gas from perforations at 7,242-344 ft. Riata later purchased Hombre's interests.
Worth Petroleum Co. opened Worth field in 1984 at 1 Pakenham, in Terrell County 33 miles northeast of Dryden.
It flowed 2.8 MMcfd of gas from Wolfcamp perforations at 11,358-375 ft.
The discovery well is 5 miles southwest of Allison field, which produces gas from Detrital at about 9,400 ft and Devonian at 10, 700 ft.
Copyright 1992 Oil & Gas Journal. All Rights Reserved.
