Pillsbury Winthrop Shaw Pittman and DLA Piper have picked up advisory roles as San Antonio-based refiner Tesoro Corporation agreed to pay nearly $2.5bn (£1.59bn) in cash to acquire the Southern California refining and marketing business of oil giant BP in an effort to expand its West Coast footprint, writes The Am Law Daily.

Tesoro is paying $1.18bn (£752m) for the assets changing hands, plus another $1.3bn (£828m) based on the value of the plant's inventory at the time of the deal's closing, which is expected before mid-2013. The deal will also see Tesoro acquire roughly 800 retail gas stations in California, Nevada, and Arizona, as well as a logistics system and assets that Tesoro said it plans to spin off to its master limited partnership, Tesoro Logistics, within a year of closing the deal with BP.

Tesoro plans to combine the business, which is based in Carson, California, with one of its own refineries located nearby. Combining the two plants would result in annual savings of almost $250m (£159m).

For BP, the sale is part of a plan to refocus the company's American fuels business, with BP confirming last year that it would look to sell the Carson facility as well as one in Texas, in order to focus on its operations in Indiana, Ohio, and Washington.

Pillsbury is advising Tesoro on the acquisition, with San Francisco corporate and securities partner Bruce McDiarmid leading the firm's team.

Other Pillsbury attorneys on the deal include energy partner Robert James; global sourcing partner Michael Murphy; compensation and benefits partner Christine Richardson; employment partner Paula Weber; corporate and securities partner Patrick Devine; finance partner Michael Hindus; real estate partner Glenn Snyder; finance partner Robert Spjut; real estate partner Laura Hannusch; and intellectual property partner Richard Zaitlen.

Partners Jerry Ross, David Farabee, and Michael Barr, as well as counsel Brad Raffle, are advising on environmental law matters. Charles Parrish is general counsel for Tesoro.

SEC filings show DLA Piper is also advising on the deal, with Houston energy partner Carlos Sole III understood to be leading a team representing BP on the sale of its business.

BP has turned to a number of firms, including DLA, in recent years as it consolidates its holdings and sells certain units in order to raise money to cover the $20bn (£12.7bn) fund meant to repay damages caused by the 2010 Deepwater Horizon oil spill in the Gulf of Mexico.