Union Pacific Resource Co. (UPRC), Fort Worth, is preparing to test a trilateral horizontal well in Brazos County, Tex., in which each lateral penetrates a different formation.
UPRC's 1 Patranello-Varisco Estate entered upper Cretaceous Austin chalk just below 6,700 ft in Giddings field, lower Cretaceous Buda below 7,200 ft in Curtin field, and lower Cretaceous Georgetown below 7,300 ft in Northeast Caldwell field. UPRC owns an 86.2% interest in 1 Patranella-Varisco and Howell Corp., Houston, 13.8%.
UPRC and Howell spudded 1 Patranella-Varisco early in September and finished drilling the Buda early in October, the Georgetown in mid-October, and the Austin chalk late in October.
The well, expected to cost about $1.5 million, cut about 4,700 ft of Austin chalk and 4,500 ft of both Buda and Georgetown reservoirs, with each lateral reaching as far as 4,900 ft from the surface location.
Altogether, UPRC and Howell drilled about 13,300 ft of horizontal sections. The laterals are stacked, with all following about the same azimuth.
UPRC and Howell completed each lateral in open hole. Production plans call for commingling oil and gas from all three laterals into a single string of 2 7/8 in. production tubing in the vertical section of the wellbore.
Well testing plans are not final. Test options include commingling production from all three zones from the outset, testing only the Austin chalk by isolating the other zones with packers or a bridge plug, or delaying perforation of production tubing at the chalk to test combined Buda and Georgetown flows.
UPRC this year consistently has had 20-25 rigs drilling UPRC operated horizontal wells, mostly to the Austin chalk in Fayette, Burleson, Brazos, Grimes, Robertson, Lee, Washington, Newton, and Jasper counties, Tex. The company expects to maintain that pace of horizontal drilling for the remainder of 1993 and into 1994.
By yearend, UPRC expects to have completed about 210 horizontal wells in South Central Texas among about 500 in North America.
UPRC said its overall horizontal drilling costs are diminishing, partly because of new technology and improved efficiency by more experienced contractors and crews. However, while most earlier horizontal wells attempted by UPRC were grassroots prospects, the company now is doing many horizontal redrills and reentries as well. So direct cost comparisons are difficult.
Copyright 1993 Oil & Gas Journal. All Rights Reserved.
