Gulf of Thailand wildcat flows high CO 2 gas

Block B8/32 Drillstem Test Results [19958 bytes]

A group of companies that includes Pogo Producing Co., Houston, has tested gas with a high carbon dioxide content in its latest discovery on Block B8/32 in the Gulf of Thailand.

Pogo reported the group's 2 Pakakrong wildcat flowed a combined 16 MMcfd of gas on drillstem tests of two sands at undisclosed depths. Partners calculated a flow of 10 MMcfd with as much as 80% CO₂ from one zone and 6 MMcfd with as much as 60% CO₂ from the other.

A third drillstem test at 4,198-4,218 ft flowed 1,636 b/d of oil through a 1/2 in. choke with 257 psi flowing wellhead pressure.

Pogo Chairman and Chief Executive Officer Paul G. Van Wagenen said Block B8/32 partners were encouraged by 2 Pakakrong's oil flow but disappointed at the high CO₂ contents in the well's gas zones.

Tests of earlier wildcats on the B8/32 concession found small CO₂ contents.

Block B8/32 operator Maersk Oil (Thailand) Ltd. unit of Maersk Olie og Gas AS, Thaipo Ltd. unit of Pogo Producing, and Thai Romo Ltd. unit of Rutherford Moran Oil Corp., Houston, each own a 31.67% interest in the 1.3 million acre concession. Thai company Sophonpanich Co. Ltd. owns 5%.

The group is exploring the Pakakrong and Benchamas structures in Maersk operated areas of Block B8/32.

Also on Block B8/32, Thaipo operates the 70,000 acre Tantawan production license area, where development drilling has been in progress since mid-1995. Partners expect to start Tantawan production in fourth quarter 1996 (OGJ, Mar. 11, p. 33).

Thaipo and Thai Romo each hold a 46.3% interest in Tantawan development and Sophonpanich 7.4%.

More work to do

Van Wagenen said CO₂ content was less than 3% in the group's 1 Pakakrong discovery well. The wildcat flowed a combined 25.5 MMcfd of gas and 738 b/d of oil and condensate on drillstem tests of two Pakakrong zones at 4,428-4,910 ft.

The 2 Pakakrong well is on a previously untested fault block, about 1 mile southeast of the 1 Pakakron discovery.

CO₂ cuts in Benchamas and Tantawan wells have not exceeded 20% and usually have been less than 10%.

"These results only tell us that we have more work to do in order to understand the complex Pakakrong structure," Van Wagenen said.

The two Pakakrong wells followed drilling of the fourth well on the Benchamas structure.

Partners early last February said the fourth successful Benchamas wildcat in four attempts flowed a combined 25 MMcfd of gas and 5,012 b/d of oil and condensate on drillstem tests of three intervals at 8,532-9,027 ft. Choke sizes on the tests ranged from 40/64 to 1/2 in. and flowing wellhead pressures from 867 to 1,323 psi.

The Sedco 601 semisubmersible rig will move from 2 Pakakrong to the Tantawan area, about 30 miles southeast, to begin drilling delineation wells. The first two wells are to be 10 Tantawan and 11 Tantawan.

Also on Tantawan, Thaipo and partners are drilling development wells with the Trident 15 jack up rig. Sedco Forex International Drilling Inc. owns and operates both rigs.

Van Wagenen said that, following delineation drilling at Tantawan, Sedco 601 likely will resume exploratory drilling at Benchamas and Pakakrong, as well as other unexplored structures on Block B8/32.

Block B8/32 update

As of Mar. 1, 1996, Thaipo and partners since late 1992 had drilled nine successful exploratory wells in 10 attempts on the seismically defined Tantawan structure (OGJ, Mar. 4, p. 75). Ten Tantawan development wells also have been drilled since mid-1995.

The 3 Tantawan wildcat in late 1993 chalked up the biggest flow, a combined 8,684 b/d of oil and condensate and 40.66 MMcfd of gas from five zones at undisclosed depths.

Partners in June 1995 said the 9 Tantawan wildcat on the far north side of Tantawan structure found hydrocarbons in several zones at undisclosed depths but was not drillstem tested. The well is 11 miles north of the 1 Tantawan discovery and 7 miles north of the previous northernmost Tantawan exploratory well.

The group plans to install production and wellhead platforms on Tantawan in mid-1996 and ultimately to drill 30 development wells.

Tantawan gas is to be sold to the Petroleum Authority of Thailand (PTT) under a 30 year contract signed in November 1995 (OGJ, Nov. 13, 1995, p. 34). Gas sold under the agreement is to flow through a 36 in. subsea pipeline PTT is laying about 25 miles west of Tantawan. Partners plan to handle Tantawan oil and condensate with a 50,000 b/d floating production, storage, and offloading unit.

Meantime, the Maersk Thailand group tested two of its first three wells on the Benchamas structure. The 1 Benchamas wildcat flowed a combined 44.7 MMcfd of gas and 4,835 b/d of oil and condensate from five zones, and 3 Benchamas a combined 33.3 MMcfd and 7,575 b/d from four zones.

The group's 2 Benchamas wildcat also found hydrocarbons at a site 6 miles south of 1 Benchamas but was not drillstem tested.