MOBIL HORIZONTAL HOLE TAPS TWO PAY ZONES

Mobil Exploration & Producing U.S. Inc. has penetrated two Gulf of Mexico gas reservoirs a half mile apart with a single horizontal hole. After drilling horizontally through the first targeted gas interval, Mobil turned the well's horizontal section slightly upward to penetrate the second zone 189 ft higher. Mobil drilled the well from E platform on High Island Block A-574 in the western gulf about 100 miles off Galveston, Tex. Greg Cox, area producing manager in Mobil's New Orleans

Feb. 6, 1995

2 min read

Mobil Exploration & Producing U.S. Inc. has penetrated two Gulf of Mexico gas reservoirs a half mile apart with a single horizontal hole.

After drilling horizontally through the first targeted gas interval, Mobil turned the well's horizontal section slightly upward to penetrate the second zone 189 ft higher. Mobil drilled the well from E platform on High Island Block A-574 in the western gulf about 100 miles off Galveston, Tex.

Greg Cox, area producing manager in Mobil's New Orleans office, likened the feat to pushing a steel pipeline up a half mile incline to the 20th floor of a building.

He estimated the cost of drilling into both reservoirs with a single horizontal hole at slightly more than $2 million, only two-thirds of the likely cost of drilling two holes.

"Horizontal wells are being used increasingly by the industry to breathe new life into mature producing such as the Gulf of Mexico," Cox said.

"They can increase production rates and make marginal fields economic."

At High Island A-374, Mobil first directionally drilled 3,584 ft of hole, intersecting the lower reservoir at 2,900 ft measured depth at a position 1,500 ft away from the rig's surface location. Next, the company drilled through about 1,000 ft of pay, then angled the hole about 4 above horizontal and drilled another half mile to penetrate the upper pay.

Both producing zones are about 100 ft thick, and Mobil horizontally cut about 1,000 ft of pay in each reservoir.

Mobil is producing about 11.7 MMcfd of gas from the lower of the two zones, about the rate at which it flowed on tests. After that zone is depleted, Mobil intends to plug back to the upper interval, also expected to produce 11-12 MMcfd.

Operator Mobil holds 53% interest in the well, Northwestern Mutual Life Insurance Co. 36%, and Total Minatome Corp. 11%.