New exploration plays in Perth and Carnarvon Basins

THE WESTERN Australian government has released four new areas in state waters and onshore for oil and gas exploration.
New exploration plays in Perth and Carnarvon Basins New exploration plays in Perth and Carnarvon Basins New exploration plays in Perth and Carnarvon Basins New exploration plays in Perth and Carnarvon Basins New exploration plays in Perth and Carnarvon Basins

WA resources minister Bill Johnston.

Paul Hunt

Senior Journalist: Oil & Gas, Policy.

Paul Hunt

Today the Department of Mines, Industry Regulation and Safety (DMIRS) announced four new exploration areas for competitive bidding. 

Exploration permit L20-1 consists of 79 blocks across the Northern Carnarvon Basin. A second permit in the Southern Carnarvon Basin known as L20-2 is also up for competitive tender and contains 33 blocks. 

L20-1 consists of both onshore and offshore acreage just south of the City of Karratha. 

More than 50 oil and gas wells have been drilled across the permit to date, however only four of these wells have been drilled offshore. The Cowle-1 well flowed oil from the Flacourt Formation sandstones at rates between720 to 1590 barrels of oil per day. Though the discovery was close to existing infrastructure it was never developed. 

Extensive historic 2D seismic has already been acquired across key areas within the permit, which is available to interested bidders.

 The second permit within the Carnarvon Basin is a pure onshore play. While there have been more than 30 seismic surveys conducted over the 33 blocks within the permit, only three wells have been drilled - the Burna-1, Wandagee Corehole-2 and Quail-1 wells. 

According to historic government analysis, obtained by Energy News, dated more than five years old, the L20-2 onshore permit contains a shale play which potentially holds the "best gas-prone source beds in the Carnarvon Basin." However this cannot be fracced under current legislation. 

ExxonMobil, which conducted a large amount of 2D seismic acquisition across the permit, drilled the Burna-1 well in 1985 but the well came up a duster due to a lack of seal. The well targeted the Moogooloo Sandstone and Top Lyons Group. 

Two more exploration permits, L20-3 and L20-4 lie within the North Perth Basin - L20-3 contains two blocks while L20-4 contains 33 blocks. 

The L20-3 permit is onshore, west of the Shire of Carnamah. Only one well has been drilled in the small permit, Warradarge-1. A company called Titan Energy drilled the well in 2013 targeting the Cadda Formation and Cattamarra Coals. The well was drilled to a total depth of 1560m but came up a duster. It also acquired seven lines of 2D seismic. 

 The final permit L20-4 has extensive seismic mapping and lies north of the Shire of Gingin and south of the Shire of Coorow. 

Three wells have been drilled in the permit - Cypress Hill-1, Yallallie-1, and Dandaragan-1. 

The Cypress Hill-1 well was drilled in 1988 and the Yallalie-1 well in 1991. Both wells, drilled about 30km northwest of Moora. The Dandaragan-1 well targeted the Dongara oilfield - one of the largest commercial fields ever discovered in the Perth Basin. 

The main source for gas is the Permian Irwin River Coal Measures, with reservoirs in the Upper Permian and Jurassic. The main source for oil is the base of the marine Lower Triassic Kockatea Shale, with reservoirs in Lower Triassic and Permian sandstones. 

Under the WA competitive bidding process, oil and gas explorers will need to provide detailed work program commitments including how many kilometers of 2D and 3D seismic will be obtained and specifically how many wells will be drilled. 

The target formations and reservoirs will also need to be outlined. 

Interested companies have until October 19 to submit their applications for the acreage. 

 

 

 

 THIS STORY HAS BEEN UPDATED TO INCLUDE SPECIFIC REFERENCE TO THE SHALE POTENTIAL OF THE MERLINLEIGH SUB-BASIN WITHIN THE L20-2 ONSHORE PERMIT. 

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