(Reuters) - Shares of U.S. oil and gas producers that own shale acreages rose on Friday, following major global miner BHP Billiton's bid to buy Petrohawk Energy at a hefty premium.

BHP will buy Petrohawk for $12.1 billion, paying a premium of 65 percent to raise its presence in shale fields, which are underground rock formations rich in oil and gas.

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http://www.reuters.com/article/2011/07/15/us-shalecompanies-shares-idUSTRE76E2OD20110715