News: STO UPDATE 1-Australia's Santos agrees to buy Quadrant Energy for at least $2.15 bln

• Comes soon after Quadrant, Carnarvon reported major oil find
• Santos to fund deal with cash and new debt facilities
• Retail conglomerate Wesfarmers to sell 13.2 pct stake

(Adds background on oil field, Wesfarmers statement)

Aug 22 (Reuters) - Australian oil and gas firm Santos Ltd (STO) said on Wednesday it has agreed to buy privately held Quadrant Energy for at least $2.15 billion, bagging access to what may be the biggest oil find off Western Australia in over two decades.

The deal comes soon after Quadrant and junior joint venture partner Carnarvon Petroleum (CVN) reported what Carnarvon called a "truly incredible" oil discovery, sending Carnarvon shares rocketing to a nine-year high.

Energy consultants Wood Mackenzie estimated the find could hold well above 150 million barrels of oil, albeit without knowing the boundaries of the reservoir.

Santos said on Wednesday the deal, to be funded by cash and $1.2 billion in new debt facilities, could potentially boost its annual production by about 32 percent. The deal is also subject to potential additional contingent payments, Santos said.

Quadrant didn't immediately comment. Before Wednesday's deal, bankers had said 50 percent owner Brookfield Asset Management BAMa.TO was looking to sell its 50 percent stake.

Macquarie Group (MQG) , Wesfarmers (WES) and mining heiress Angela Bennett are also Quadrant investors.

Retail conglomerate Wesfarmers said in a separate statement on Wednesday that it would be selling its 13.2 percent Quadrant stake for $170 million, and expects to bank a $98 million pre-tax profit on the deal's completion.