Australia is seeking applications for exploration rights on nine areas off its western, northern, and southern coasts.
Meantime, the Australian Petroleum Exploration Association (APEA) predicts Offshore Western Australia will be the focus for more than half the wildcats drilled in Australia this year.
APEA also predicts Australia's oil self-sufficiency will fall to about 71% by the mid-1990s from the current 88%.
EXPLORATION ACREAGE
Alan Griffiths, commonwealth minister for resources, said the offering includes areas with identified petroleum potential off Western Australia, lightly explored areas off Northern Territory and Queensland, and frontier areas off Tasmania.
Acreage available in the country's first offering this year includes:
- Four permits off Western Australia in the Carnarvon basin.
- Two permits in the Bonaparte basin off Northern Territory.
- One permit off Queensland in the Carpentaria basin.
- Two permits off Tasmania-one each in the Gippsland and Sorell basins.
Two of the Carnarvon basin permits are available under the cash bidding system in which a permit will be awarded to the highest bidder. The remaining areas are offered under a modified work program bidding system in which applicants are required to guarantee a minimum level of exploration.
All the permits are for 6 year terms. Deadline for applications is Oct. 23, 1992.
CARNARVON BASIN
The four permit areas off Western Australia are in the northern part of the Carnarvon basin.
Areas W92-1, W92-2, and W92-3 are in the Dampier subbasin, and W92-4 is in the Exmouth subbasin.
Areas W92-1 and W92-2 are cash bid permits and contain six and four blocks, respectively. Lying in 70-90 m of water, they are about 80 km northwest of the Burrup Peninsula and 50 km southwest of North Rankin A gas/condensate production platform,
Australian officials said at least 10 wildcats have been drilled in the immediate area of W92-1 and W92-2, and seismic coverage is a relatively dense grid.
Area W92-1 overlies the Rankin platform, a series of north-northeast trending en echelon horsts and grabens. Rankin platform is also the site of North Rankin and Goodwyn fields to the northwest.
Area W92-2 overlies part of the Parker terrace east of the Rankin platform, where Jurassic-Cretaceous deposits thin from about 7 km in the main trough.
Area W92-3 consists of four blocks in 55-75 m of water about 60 km northwest of the Burrup Peninsula. Geology is similar to areas W92-1 and W92-2, with a potentially thicker upper Jurassic section. There are oil and gas discoveries in the region.
Area W92-4 consists of four partial blocks covering about 60 sq km in water depths of 20-80 m, deepening to the northwest. It is about 7 km from North West Cape and 5 km northwest of the Muiron Islands.
The area is the site of Australia's first flowing oil well, 1 Rough Range, drilled in 1953. Main targets include Triassic Mungaroo, upper Jurassic Dupuy, and Cretaceous Barrow group and equivalents.
Nearby is Lasmo plc's 1 Leatherback discovery, which flowed at a maximum rate of 2,626 b/d of oil from Mungaroo (OGJ, July 15, 1991, p. 48).
BONAPARTE BASIN
The two permit areas off Northern Territory are in the north and northeast parts of the Bonaparte basin about 300 km northwest of Darwin.
Water depth is less than 100 m over most of the areas but increases to about 450 m in the northern part of NT92-2.
NT92-1 and NT92-2 overlie the Malita graben, a northeast-southwest trending trough that originated during the middle Jurassic. The area has a thick late Mesozoic-recent section. The graben is characterized by northeast-southwest trending tilted Mesozoic fault blocks.
Exploration in the area began in the mid-1960s. About 7,100 line km of seismic data cover the two areas.
Two wells have been drilled in NT92-1, one of which had numerous gas shows in the Cretaceous and Jurassic. The other well found residual oil stain in the Jurassic. Three wells have been drilled adjacent to the areas, including a gas discovery.
Target reservoirs are Jurassic Plover and Flamingo group and Cretaceous Bathurst Island group.
CARPENTARIA BASIN
Area Q92-1 is in the Gulf of Carpentaria in about 65 m of water 100 km west of the town of Weipa on Cape York Peninsula off Queensland. It includes 370 blocks in a largely unexplored sector of the Carpentaria basin.
The permit is in the north central part of the Jurassic-Cretaceous basin that has a maximum combined thickness of Jurassic and Cenozoic sediments of about 1,750 m.
Only one well has been drilled offshore. It was plugged at 1,117 m after drilling from Cretaceous Wallumbilla into Precambrian basement without finding hydrocarbons.
Australian officials said the area is one of the largest off Australia that remains untested.
OFF TASMANIA
The areas being offered off Tasmania are T92-1 off the state's western coast and T92-2 off the eastern coast.
T92-1 covers 136 blocks adjacent to the coast and extending into water about 2,000 m deep.
The area includes King Island and Sandy Cape subbasins of the Sorell basin.
Officials said the subbasins are believed to hold 3,600-5,100 m of late Mesozoic and Cenozoic sedimentary infill, but the area is little explored. Seismic data in the area are all pre-1975.
T92-2 covers 104 blocks in the Gippsland basin in water mostly about 200 m deep but exceeding 1,000 m along the eastern boundary.
Australian officials said the northern two thirds of the area is covered by a grid of about 720 line km of good quality seismic acquired in 1980-83.
Three wells have been drilled in the area, all in the northern part and all dry.
Officials said the Golden Beach group has not been drilled in any of the wells, and the Cretaceous Latrobe group has not vet been drilled in a structural trap.
WESTERN AUSTRALIA ACTIVITY
Of the maximum 60 wells to be drilled off Australia this year (OGJ, Jan. 27, p. 57), 30 are planned off Western Australia, APEA reported.
The state also will see five appraisal wells and more than 246,400 line km of seismic survey conducted during 1992.
Companies plan to spend about $1.1 billion (Australian) on development projects off Western Australia this year.
Onshore Western Australia activity calls for outlays of $12 million covering 10 wildcats and two appraisals.
Recent discoveries off Western Australia still under consideration for development include Angel gas, Wanaea oil and gas, Gorgon gas/condensate, Harriet gas, and Roller and Bambra oil fields.
Coming off the possible development list is Griffin oil field, where a group led by BHP Petroleum Pty. Ltd. last month disclosed plans for a $600 development project (OGJ, May 18, p. 32).
SELF-SUFFICIENCY
APEA predicts Australian oil self-sufficiency will rebound to 75% after undergoing the 17 percentage point slide the next few years.
That revival will be fueled by start of production from recent discoveries off Western Australia.
APEA also contends there is a 50% chance Australia's crude production can be maintained at mid-1990s levels past 2000. That assumes 25% of future production will come from fields still to be discovered.
To achieve that goal, Australian operators will have to find about 2 billion bbl of reserves at a cost of about $25 billion for exploration and development the next 8 years.
Australia's oil self-sufficiency in 1991 averaged about 84%. Production of oil and condensate averaged 545,000 b/d, a drop of 5.6% from 1990 (OGJ, Apr. 27, p. 57).
