Exploration is turning up significant oil discoveries on the gas prone Northwest Shelf off Australia.
Among the latest action, Western Australia Petroleum Pty. Ltd. (Wapet) tested another sizable oil and gas discovery.
Wapet partner Chevron Overseas Petroleum Inc. (COPI) reported the discovery and detailed production results from other recent strikes as well as current exploration and drilling activity in the region off Western Australia at a security analysts' meeting in New York.
Separately, a unit of Broken Hill Pty. Co. Ltd., Melbourne, reported test results from the 1 Griffin discovery in the Barrow subbasin of the Northwest Shelf.
Elsewhere, BHP Petroleum took a farmout on a Bass Strait exploration permit off southern Australia.
ROLLER STRIKE
Wapet 1 Roller on the Northwest Shelf flowed at a stabilized rate of 5,450 b/d of 29.7 gravity oil and 1.04 MMcfd of gas through a 11/4 in. choke with 360 psi wellhead pressure from Cretaceous Barrow/Flacourt perforations at 2,987-3,000 ft.
The well, spudded Jan. 4 and tested Jan. 28, is in 39 ft of water on Wapet TP/3 Part One permit. It bottomed at 4,370 ft.
The Wapet group moved the Maersk Valiant jack up, which drilled the discovery well, to directionally drill the 1 -A Roller stepout from the 1 Roller surface location about 1/2 mile north-northwest.
The Roller strike is about 8 miles south-southwest of the Wapet 1 Cowle discovery on the same permit and about 50 miles south of Barrow Island.
The 1 Cowle flowed 6,390 b/d of 480 gravity oil and 1.95 MMcfd of gas through a 15/16 in. choke with 600 psi wellhead pressure from Barrow/Flacourt at 3,603-12 ft. An earlier report placed the flow at 8,390 b/d from an interval at 1,098-1,100 ft (OGJ, Jan. 8, p. 30).
Participants in the two finds are COPI unit Chevron Asiatic Ltd., Shell Development (Australia) Pty. Ltd., and Texaco Oil Development Co. 25.7% each, Ampol Exploration Ltd. 12.9%, and Western Mining Corp. Ltd. 1 0%.
The proximity of both finds to Saladin field brightens prospects for their early development.
Saladin, also operated by Wapet, started production of about 25,000 b/d in December (OGJ, Dec. 11, 1989, p. 36). It produces from the same pay-Flacourt at 3,609 ft-as the Roller and Cowle finds. So does nearby Yammaderry offshore oil field, also operated by Wapet.
Saladin is expected to reach peak output of 60,000 b/d early this year and continue producing for 5-7 years.
COSSACK-WANAEA ACTION
Meantime, a group led by Woodside Petroleum Ltd. is conducting further delineation and exploration work in the area surrounding the Cossack and Wanaea discoveries.
Chevron disclosed production results from the Cossack discovery, which Woodside reported in January cut a 165 ft gross oil column (OGJ, Jan. 22, p. 20).
The group's 1 Cossack flowed 7,200 b/d of 49 gravity oil through a 1 in. choke with 360 psi flowing tubing pressure from Jurassic Tithonian perforations at 9,4829,51 5 ft.
The well, spudded Nov. 16, 1989, is about 50 miles north of Barrow Island and about 85 miles off the northwestern Australian coast.
It was drilled to 9,941 ft in 270 ft of water. Testing was completed in late January after a short hiatus when the drilling vessel Margie was evacuated because of Cyclone Sam.
The Cossack find is 4.6 miles northeast of the Wanaea discovery well. Both are on the WA-28-P permit operated by Woodside.
Chevron, a partner in both, noted that the two finds are believed to be on separate structures despite their closeness. Further delineation drilling and testing of both are required before reserve estimates can be confirmed, Chevron said.
Earlier, industry officials estimated the two structures could contain as much as a combined 300 million bbl of oil. The petroleum division of Australia's Commonwealth Department of Primary Industries and Energy called the two "Madeleine" trend discoveries probably the most significant oil strikes in Australia in years.
The group plans two appraisal wells and more seismic surveys in the area.
The Woodside group spudded the first delineation, 2 Wanaea, about 2 miles southwest of the 1 Wanaea on Jan. 30. A second appraisal is planned.
The 1 Wanaea flowed at a stabilized rate of 5,480 b/d of 48.8 gravity oil and 3.65 MMcfd of gas through a 1 in. choke with 650 psi tubing pressure from Tithonian sandstone perforations at 9,521-48 ft (OGJ, Aug. 28, 1989, p. 15).
Partners in WA-28-P, each holding a 162/3% interest, are Woodside, Chevron, Shell, BP Development Australia Ltd., BHP Petroleum (NWS) Pty. Ltd., and Japan Australia LNG (MIMI) Pty. Ltd.
BHP GRIFFIN WELL
BHP Petroleum 1 Griffin flowed at a stabilized rate of 5,400 b/d of 540 gravity oil through a 3/4 in. choke with 886 psi flowing pressure from Cretaceous Barrow at 8,71440 ft.
The well also flowed oil at a maximum rate of 6,400 b/d through a 70/64 in. choke with flowing pressure of 593 psi.
Site is on WA-210-P permit about 60 miles northeast of Exmouth.
Plans call for further production tests of a shallower interval.
Cretaceous Barrow is also the pay in Harriet, South Pepper, and North Herald fields, closer to shore.
At least two appraisals are likely to delineate the field. BHP would not estimate potential reserves, but other industry officials in Australia speculated the accumulation might be about 100-150 million bbl.
BHP said commercial prospects at Griffin look very encouraging.
The Energy Searcher drillship spudded the well in December and conducted the production test (OGJ, Feb. 5, p. 30).
As permit operator, BHP holds a 45% interest. Its partners are Mobil Exploration Australia Pty. Ltd. 35% and Inpex Alpha Ltd. 20%.
BHP FARMOUT
BHP Petroleum's farmout covers a 56.7% interest in Bass Strait permit VIC P-25 in the far southwest corner of the Gippsland basin off Victoria state.
Previously, the permit was held by four Australian companies, each with a 25% interest.
Under the agreement, Austin Oil NL, North Broken Hill Peko Ltd., and AGL Petroleum will reduce their interests to 9.25% each, and Crusader Ltd. unit Pursuit Exploration Pty. Ltd. will cut its interest to 15.55%.
BHP will pay 90% of the cost of two wildcats before the end of July and Pursuit the remaining 10%, while the other three companies will be carried free through the program.
On a dry hole basis, the two wildcats are estimated to cost a total of $6 million (Australian).
The combine will hire the Southern Cross semisubmersible for the program.
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