Horizontal drilling in the Cretaceous Austin chalk trend of South Texas continues to set a fast pace.
The Texas Railroad Commission has issued nearly 900 permits to drill horizontal wells in the Pearsall field area alone from 1984 through February 1991.
TRC issued 1,485 permits for horizontal wells statewide during that period, including 1,285 since Jan. 1, 1990.
Statewide, operators have reported completion of 685 horizontal wells. That includes 472 in Pearsall field, where TRC has issued 882 permits, and 121 in Giddings field, where 305 permits have been issued.
Frio County, site of Pearsall field, led Texas counties with 494 permits and 278 horizontal completions.
Among the busiest Pearsall operators is Oryx Energy Co., Dallas, which holds about 260,000 net acres in and around the field. It estimates more than 300 wells will be required to develop its holdings, including 75 it has already drilled.
Oryx said that the estimate could increase as it expands into about 150,000 untested net acres.
Industry's drilling pace is particularly brisk 45 miles east of San Antonio in the First Shot field area, which covers parts of three counties southwest of Giddings field.
Oil drilling and reentry work is under way in many areas, and horizontal Austin chalk gas/condensate completions have been reported in Dimmit and Burleson counties.
ORYX PRODUCTION
Oryx's Austin chalk drilling program yielded 5.4 million gross bbl of oil and 2.7 net bcf of natural gas last year. It expects to produce about 8.8 million bbl of Austin chalk oil this year.
Oryx also expects the average successful horizontal well to add as much as 450,000 bbl of proved crude oil equivalent reserves and initially to produce 750 b/d net.
FIRST SHOT FIELD
Drilling is fervent in the First Shot field area near the junction of Gonzales, Wilson, and Karnes counties, even though the pace and number of wells do not rival those in Pearsall or Giddings fields.
Several operators are exploring for and developing Austin chalk oil in the greater First Shot area.
They include Chesapeake Operating Co., Austin; Leede Oil & Gas, Englewood, Colo.-, Royal Oil & Gas Corp., Brayton Oil Co., Tana Oil & Gas Co., and Apex Operating Co., Corpus Christi; Santa Fe Energy Operating Co., Wainoco Oil & Gas Corp., Conoco Inc., and Cox & Perkins Exploration Co., Houston; Petro-Hunt Corp. and Petratex Resources Co., Dallas; and Chippewa Resource Co., Denver.
Other operators are working on horizontal wells in the same general area in Nixon, Southeast Nixon, Marcelina Creek, Cindy Ann, and Higgins fields of Wilson County.
PRESIDIO'S DISCOVERY
Presidio Oil Co., also of Englewood, gauged 1H Coates Ranch, a discovery in Wilson County 7 miles west of the main part of First Shot field of Gonzales County.
It flowed at a rate of 2,375 b/d of oil and 2.1 MMcfd of gas through a 48/64 in. choke with 1,040 psi flowing tubing pressure from Austin chalk.
The well, on the East Marcelina Creek prospect, is 100% owned by Presidio. It tested a prospect generated and assembled by Paramount Petroleum Co. Inc., Houston, and Paramount affiliate Discovery Oil & Gas.
Presidio owns an average 92% working interest in about 14,500 acres in the immediate area of the strike.
Presidio is attempting to complete 1H Maddux-Paramount, a First Shot field well in Karnes County 2 miles north of Gillett.
And it is drilling 1H Wilke-Paramount, a horizontal chalk development well 3 miles east of the 1H Coates Ranch in Elm Creek field of northern Karnes County.
Presidio plans to drill six to nine more Austin chalk wells this year. It owns interests in about 33,500 acres in the trend, where it has run extensive seismic surveys the past year.
MERIDIAN'S PROGRAM
Meridian Oil Inc., Houston, which opened First Shot field last summer, has completed another strong horizontal Austin chalk oil well in the field and signed an Austin chalk operating agreement with Marathon Oil Co.
Meridian completed 1 Schaefer-Manford Unit, 2 1/2 miles south-southwest of Smiley in Gonzales County.
It flowed at a calculated daily rate of 8,974 b/d of 380 gravity oil with 11.7 MMcfd of gas and 7,424 b/d of water from open hole at 9,187-11,792 ft.
Meridian ran the test while the rig was on location.
It ran 3 1/2 in. drill pipe to 7,775 ft, and flow was through the 7 5/8 in. by 3 1/2 in. annulus through two 1 9/16 in. chokes, Petroleum Information reported. Permit for the well was issued to Sanchez-O'Brien and Texaco Inc., and Meridian assumed operations at about 8,175 ft, once drilling of the horizontal part of the hole began.
Meridian opened First Shot field in mid-1990 at 1H Smith, 4 1/2 miles south-southwest of Smiley and 2 miles south of Giddings field.
The discovery well flowed 12,254 b/d of oil, 4.9 MMcfd of gas, and 3,032 b/d of water through two 2 1/16 in. chokes with 300 psi flowing tubing pressure from open hole at 8,783-11,368 ft. Horizontal displacement is 2,899 ft.
MARATHON-MERIDIAN VENTURE
Marathon and Meridian agreed to explore and develop 45,000 acres of Meridian leases along the Austin chalk trend. Marathon will operate 15-20 horizontal wells on fifteen 3,000 acre tracts in five counties the next 13 months. It can earn significant working interests in the tracts.
Marathon holds interests or options in about 90,000 acres in 12 counties in the chalk trend. Meridian owns additional offsetting leases totaling more than 200,000 acres.
Marathon has extensive horizontal drilling experience in Michigan and West Texas and has drilled the deepest true vertical depth (TVD) horizontal well in the U.K. North Sea. It completed four horizontal wells on other Marathon interest acreage in the Austin chalk play last year and anticipates drilling a total of more than 30 wells in the play this year.
ATASCOSA COMPLETION
Atascosa County, lying between Frio and Wilson counties, has its first successful horizontal well completion.
Texas Royalty Corp., Tyler, completed 1 Brauchle in Pearsall field, 7 miles northwest of Charlotte.
The well, with a horizontal drainhole length of 2,555 ft, flowed 523 b/d of oil and 175 Mcfd of gas through a 24/64 in. choke with 160 psi flowing tubing pressure from Austin chalk B-1. TVD is 5,674 ft.
While drilling at a horizontal length of 1,566 ft, the well cut a fracture that blew all drilling fluid from the hole, the company said. Within 30 min oil flow at the surface was 350 bbl/hr.
Texas Royalty flowed the well 12 hr through a 2 in. choke with 300 psi flowing casing pressure. The well flowed 3,500 bbl of oil before the company began attempts to control it to resume drilling. Drilling then continued "live."
Texas Royalty has more than 4,000 acres under lease in Pearsall field and plans to develop the tracts during the next 3 years.
It was starting 1-A Yancy, a 4,000 ft offset to 1 Brauchle. Horizontal length of the new well is to be 3,000 ft.
The next well will be 1 Avant, a 2,700 ft horizontal well to be drilled in late June 1/4 mile southeast of Dilley in Frio County.
TRC has issued five permits to drill horizontal wells in Atascosa County (OGJ, Jan. 21, p. 41). At least one was dry. The other three are in various stages of preparation to drill or drilling/completion.
OTHER CHALK DRILLING
Alexander Energy Corp., Oklahoma City, plans to operate at least 20 of 30 Austin chalk horizontal wells to be drilled in Burleson County.
Evaluations show gross reserves could exceed 5 million bbl of oil and 28 bcf of gas, including 773,000 bbl and 5 bcf net to the Alexander Energy/John Hancock Mutual Life Insurance Co. 1987 limited partnership.
Alexander plans to drill 2H Morris in Somerset field of Bexar County, north of the Austin chalk trend fairway. Objective is a 2,000 ft horizontal leg in Austin chalk at about 3,780 ft.
Adams Resources Exploration Co., Houston, is reentering 2H Birch Creek Park in Burleson County, 15 miles southeast of Caldwell, Tex., in Giddings field. A 2,800 ft horizontal leg is to be drilled in Austin chalk.
The vertical well was completed in 1983 flowing 103 b/d of 50.2 gravity oil, 562 Mcfd of gas, and 53 b/d of water through an 11/64 in. choke with 1,775 psi flowing tubing pressure from open hole at 9,857-10,238 ft.
GAS/CONDENSATE WELLS
A few horizontal gas and gas/condensate completions are cropping up in the greater Austin chalk play.
GLG Energy Co., Austin, recently tested Texas' second horizontal gas producer.
The 1 Briscoe, in the Pearsall field area in Dimmit County, flowed 2.363 MMcfd of gas and 67 b/d of condensate at 486 psi flowing tubing pressure from Austin chalk open hole at 5,933-6,407 ft.
Union Pacific Resources Co. completed the first horizontal gas well in Texas last October.
Its 1 Cottonwood Bayou, in Giddings field of Burleson County, flowed 2.068 MMcfd of gas through a 38/64 in. choke with 915 psi flowing tubing pressure from open hole at 9,976-12,073 ft.
Copyright 1991 Oil & Gas Journal. All Rights Reserved.