Privately owned Australian operator Western Gas has finalised a contract with offshore drilling giant Valaris to drill a large gas prospect off Western Australia in March and April.

Western Gas said the formal drilling contract covers the use of the semi-submersible rig MS-1 to drill the Sasanof-1 exploration well in Block WA-519-P in the Carnarvon basin.

The Sasanof-1 exploration well has the potential to contain 7.2 trillion cubic feet of gas and 176 million barrels of condensate on a prospective resource basis, with a 32% geological chance of success.

The operator also said a transaction has been completed for Australia's Global Oil and Gas to provide 50% of the well funding to earn a 25% interest in the permit.

Drilling costs are estimated at US$20 million to $25 million.

“We are delighted to award Valaris this contract given its global expertise backed by its extensive knowledge of operating offshore Western Australia. With the drilling slot locked in with Valaris and GLV secured as a partner, we are now well on our way to delivering one of the highest impact wells to be drilled on the North West Shelf in decades,” Western Gas' executive director Will Barker said.

Global Oil and Gas' executive director Patric Glovac said: “Having the calibre and expertise of Valaris involved as rig operator should provide all our shareholders with an extra degree of confidence."

Western Gas is the owner of the nearby Equus gas complex, which comprises multiple medium-size discoveries that, combined, contain a discovered resource of 2 Tcf and 42 million barrels of condensate, said the company.

The Sasanof prospect is on trend and updip of one of the discoveries in the Equus complex — Mentorc — and is near the giant Scarborough and Jansz-Io fields.

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