In a move by another European independent taking a stake in U.S. shale plays, Italian integrated energy company Eni SpA (NYSE: E) plans to acquire a 27.5% interest in core Barnett shale acreage in Tarrant and Denton counties, Texas, from Fort Worth-based Quicksilver Resources Inc. (NYSE: KWK) for $280 million in cash.

Eni is taking an interest in Quicksilver’s Alliance properties in the Fort Worth Basin, of which the current leasehold covers approximately 13,000 net acres total. Current production is approximately 60 million cu. ft. of gas per day. Eni will acquire 131 billion cu. ft. equivalent of proved reserves and 96 billion of probable and possible resources.

In 2009, Eni’s net production share from the acquired assets is expected to amount to an average of 4,000 BOE per day, the company says, growing to approximately 10,000 barrels in 2011. The company expects to drill approximately 300 wells by 2013.

The transaction does not include Quicksilver’s midstream gathering infrastructure or any of its existing leasehold beyond the Alliance properties.

Additionally, the companies have formed a strategic alliance to acquire, develop and exploit resources in an area covering approximately 270,000 acres surrounding Quicksilver’s Alliance holdings in which Eni will also have the right to a 27.5% participation. Quicksilver will be the operator of newly acquired properties. The alliance will involve a mutual technical exchange between the two companies, particularly in drilling and completion technologies and geophysics.

Quicksilver president and chief executive Glenn Darden says, “This transaction, which represents just 5% of our company’s total proved reserves at year-end 2008, is the initial step to delever our balance sheet while establishing a framework that provides meaningful opportunities to capitalize on Quicksilver’s expertise in the identification, acquisition and development of shale-gas resources. Our agreement with Eni will enable us to expand our footprint beyond the existing Alliance acreage and could lead to additional opportunities in unconventional plays outside of this basin.”

The effective date is April 1. Closing was expected by June 15. Merrill Lynch & Co. is advisor to Quicksilver.

In the U.S., Eni owns lease interests in 565 blocks (392 in the Gulf of Mexico and 173 in Alaska). In the Gulf, the company is among the leading producers with a daily net production of 100,000 BOE (60% operated).

Analysts at Tudor, Pickering, Holt & Co. Securities Inc. value the deal at $2.15 per flowing thousand cu. ft. equivalent and $102,000 per flowing BOE and characterize the deal metrics as “strong.” The deal defines core metrics of the Barnett at $2 per thousand cu. ft. equivalent, with noncore metrics at $1 per thousand cu. ft. equivalent as defined by the recent sale by Denbury Resources Inc., Dallas (NYSE: DNR).

Following resource-play purchases by Norwegian national oil company StatoilHydro (NYSE: STO; Oslo: STL) and British major BP Plc, London, (NYSE: BP) the TPH analysts suggest European companies “clearly want to understand the secret sauce around shale-gas development. Joint ventures show StatoilHydro and Eni are thinking it easier to watch over an established player’s shoulder than to do it themselves—logical and faster, albeit more expensive than by organic process.” Will the big guys keep buying, they ask? “Probably.”

Citi analysts value the deal at $7 per BOE, based on 40,000 bbl. of oil per day (23,000 barrels proved, 17,000 proved plus probable), although they note that “much of the value is likely to be in the resource potential.” They see the valuation metrics as positive, with a “solid” per acre value of $78 and $102,000 per flowing barrel ($17,000 per thousand cu. ft. equivalent) to Quicksilver.

Standard & Poor’s Ratings Services has revised its outlook on Quicksilver to developing from negative and affirmed its B corporate credit rating on the company. It also placed its issue-level rating on the company’s second-lien facility on CreditWatch with positive implications.

The majority of the proceeds are likely to be applied to the company’s second-lien debt facility, reducing it to $320 million, “which should provide additional cushion under that facility’s asset coverage covenants,” says S&P credit analyst Amy Eddy. “The reduction in debt is also likely to result in improved recovery for holders of the second-lien facility.” As of March 31, Quicksilver had more than $2.5 billion in total adjusted debt.