Australia’s Quadrant Energy and Carnarvon Petroleum have found an oil field off Western Australia that analysts said could be the biggest discovery in the area for more than 20 years, potentially turning both into takeover targets.

Describing the find as “truly incredible,” junior joint venture partner Carnarvon said on Aug. 8 more oil had been found in the Dorado-1 well with the thickness of the oil column now measured at 132 m (433 ft). That was up from the 80 m (262 ft) indicated in a drilling update in July.

Carnarvon shares rocketed to a nine-year high after the announcement and last traded up 25% at 60.5 cents, valuing the company at A$720 million (US$535 million).

Unlisted Quadrant was potentially worth A$3 billion before the Dorado find with bankers saying its 50% owner Brookfield Asset Management is looking to sell its stake.

Private equity firms are expected to drive a wave of merger activity in Australia’s oil and gas sector, hunting for assets in a market with good access to China and Southeast Asia, where energy demand is rapidly growing.

Energy consultants Wood Mackenzie said they saw the discovery as the biggest in Western Australia in more than two decades in an area better known for its gas.

“I think easily it would be above 150 million barrels, and I think it’s heading much further north than that,” Wood Mackenzie analyst David Low said.

Carnarvon, with a 20% stake in the venture, said it was excited about the prospect, now being assessed by operator Quadrant, owned by Brookfield, Macquarie Group, Wesfarmers and mining heiress Angela Bennett.

In an emailed comment Quadrant Energy CEO Brett Darley said the early results were “extremely promising.”

“The oil discovered in the Caley Member [of Dorado-1] is very significant in terms of its likely scale and in proving that this play works in the basin,” Carnarvon Managing Director Adrian Cook said in a statement.

Wood Mackenzie’s Low said the find would boost interest in both partners in the project.

“It looks like there’s a lot of upside for Carnarvon. It could be interesting for someone who wants to get into oil in Australia,” Low said.

Bankers say Quadrant had considered an IPO but scrapped the plan early this year with Brookfield still looking to sell its stake.

Low said the Dorado oil find would now boost the value of Quadrant as oil would be cheaper to develop than gas and would have a ready market in Asia.

“It definitely makes it a bit more attractive. It’s now got more of a diversified portfolio. It has an oil play now,” Low said.

Quadrant supplies more than a fifth of the domestic gas market in Western Australia and does not need more gas yet in a region with abundant gas reserves vying to be developed.

($1 = 1.3468 Australian dollars)