Unocal Corp. has marked milestones in key natural gas development projects in and outside the U.S.
The company last week started gas production from Mobile Bay facilities off Alabama.
In addition, Unocal revised its development plan for Jakrawan gas field off Thailand. It contends the change will let it bring the field on line sooner than expected.
Meantime, Unocal's Indonesian unit found gas and condensate near giant Peciko field in the Mahakam Delta off East Kalimantan. It also extended two other fields in East Kalimantan.
ALABAMA
Unocal started gas production at 70 MMcfd from Mobile 916 field.
The field is producing from five wells: three that tap Jurassic Norphlet sands below 22,000 ft and two that are completed in Miocene pay at 1,5004,000 ft.
Mobile 916 area facilities, which include a central processing platform, quarters platform, two wellhead platforms, and two caisson wells on Block 915, can handle 150 MMcfd of sweet gas and 30 MMcfd of sour gas.
Unocal operates and holds a 45.65% working interest in Mobile 916 field. Its partners are Chevron U.S.A. Inc. 45.65% and Offshore Bechtel Associates 8.7%.
Mobile 916 is Unocal's third deep gas field in the Norphlet trend, following Mobile 904 and 861 fields. Mobile 861, operated by Chevron, is producing 12 MMcfd. Mobile 904 is shut in.
Unocal's first Norphlet well in the Mobile area, Mobile 916 2 OCS-G 5753, was drilled in 1991 and flowed gas at rates of as much as 42 MMcfd from 23,066 ft. That was followed in 1994 by Mobile 916 3 OCS-G 5753, which flowed 32.5 MMcfd and cut 125 ft of Norphlet pay below 22,700 ft.
This year, Unocal wrapped up drilling and evaluated Mobile 961 2 OCS-G 5761. Plans are to complete the well and tie it into Mobile 916 facilities.
Jack Schanck, Unocal group vice-president for oil and gas operations, said his company has identified several prospects in the Mobile area for further drilling.
"A key element will be to dovetail development drilling with facility capacity to avoid overdevelopment while highgrading all drilling prospects in the area," he said.
Unocal is one of the biggest lessees in the Mobile Outer Continental Shelf area with more than 70,000 net acres in 20 blocks. The Norphlet structure underlies all or part of seven of the blocks with a total of more than 40,000 acres.
Unocal, Chevron, and Bechtel were apparent high bidders on five blocks adjacent to Mobile 916 in the recent Gulf of Mexico federal lease Sale 152 (OGJ, May 22, p. 24).
THAILAND
Unocal expects its revised development plan for Jakrawan field to allow start of production in mid-1996 instead of late 1996 as previously projected as well as boost production from original estimates.
Plans now call for installing more wellhead platforms and interfield pipelines while upgrading offshore processing facilities. These steps will eliminate the need for building a central processing platform in the field.
Unocal plans to install 15 platforms using a new, lower cost design as well as miniplatforms. All of the wells will use slimhole technology that further cuts costs.
ln addition to trimming costs, the new development plan will allow Unocal to boost 1996 production to 150 MMcfd from 120 MMcfd under the old plan.
Unocal Thailand Pres. Brian Marcotte said, "The revisions result from a desire to improve the overall economics of the field. This more cost efficient development will result in significant savings from an earlier plan."
Jakrawan, Funan, and Surat fields are covered under a third gas sales contract with Thailand's state owned Petroleum Authority of Thailand. Three other fields in the contract area, Pakarang, Trat, and Gomin, also are planned for development during the next 3 years.
Gross production from all Unocal fields off Thailand will hold steady at 700-750 MMcfd until second quarter 1996, then rise to 900-950 MMcfd when a second pipeline to landfall at Rayong goes on line. Unocal's Gulf of Thailand gas production, 705 MMcfd in 1994, has averaged 720 MMcfd this year.
INDONESIA
Unocal Indonesia Co. 1 Peciko West, drilled about 2 km west of Peciko field, flowed 14.7 MMcfd of gas and 167 b/d of condensate on three drillstem tests. lt was drilled to 11,644 ft true vertical depth (TVD), 12,762 ft total measured depth (TMD).
A sidetrack from the surface location, 2 Peciko West, flowed 12.4 MMcfd of gas and 872 b/d of condensate through a 56/64 in. choke with 1,035 psi flowing tubing pressure on drillstem test of pay at 14,830-850 ft.
The sidetrack was drilled about 10,600 ft north of the No. 1 well bottomhole location and 1,100 ft deeper stratigraphically. Well logs indicate several pay zones.
The sidetrack hole is being deepened, and more wells are planned before development plans are final.
Water depth is about 140 ft.
Elsewhere in East Kalimantan, Unocal's reentry of a well in Sepinggan field found oil in a new fault block, extending the field east. In addition, a step-out extended Serang field more than 2 km north.
Unocal's S-1 Sepinggan was reentered after producing for 20 years. It was drilled to 11,238 ft TVD and 12,293 ft TMD to test the east flank of the field, discovered in 1973. The reentry, found oil downdip and is producing 1,925 b/d of oil and 2.7 MMcfd of gas.
Water depth is about 150 ft.
Unocal 1 Serang North found oil and gas more than 2 miles north of the Serang SA platform. It cut 170 ft of net gas pay and 16 ft of net oil pay in shallow deltaic sands. Productive zones were confirmed by repeat formation tests, with drillstem tests deemed unnecessary.
The Serang well, in 339 ft of water, significantly extends the field's gas reservoirs and opens the potential for added oil production. Plans (,all for more delineation drilling from the Serang SA platform.
Oil and gas reserve additions are being further assessed in Peciko, Sepinggan, and Serang fields.
Unocal Indonesia, under a production sharing contract with state owned Pertamina, operates six fields off East Kalimantan, with 100% interests in Serang, Sepinggan, Melahin, Kerindingan, and Yakin and a 50% interest in supergiant Attaka. Unocal holds 100% interests in the two Peciko West,wells.
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