NEW YORK (Bloomberg) — Energy XXI (Bermuda) Ltd., the crude producer whose stock price more than doubled this year, agreed to buy stakes in 30 Gulf of Mexico oil fields from Japan's Mitsui & Co. for $283 million.

The transaction will increase Energy XXI's output by 43 percent, lower operating costs and add reserves of higher-value crude relative to natural gas, the company said today in a statement. The deal will double Energy XXI's stakes in fields acquired in a June 2007 from Pogo Producing Co.

Energy XXI plans to fund the acquisition with cash, bank debt and by issuing new shares, according to the statement. Bermuda-based Energy XXI rose 16 cents, or eight percent, to $2.15 in afternoon trading on the Nasdaq Stock Market after earlier surging 11 percent.

"This is a transformational transaction for Energy XXI," chief executive officer John Schiller said in the statement.

Schiller, a former vice-president of exploration and development at Devon Energy Corp., has almost doubled Energy XXI's production in the past two and a half years. The company owns a stake in a former Exxon Mobil Corp. field that partner McMoRan Exploration Co. last year said may hold billions of barrels of oil.

MSD Capital LP., which manages the fortune of Dell Inc. chief executive officer Michael Dell, is the largest holder of Energy XXI stock, with a 6.5 percent stake as of September 30.