NEW YORK ( TheStreet) -- As a way to repay billions in damages related to its 2010 Macondo oil spill, BP ( BP - Get Report) will sell $5.5 billion in Gulf of Mexico oil drilling assets to Plains Exploration and Production ( PXP), in a deal that raises less cash than initial media reports from August suggested.

BP said it will sell its Marlin, Dorado, King, Horn Mountain and Holstein oil fields to Plains Exploration and Production, as part of a strategy to sell what it deems are "non-strategic" assets to raise $38 billion for spill claims by 2013. In May, BP defined these fields as non-strategic, paving the way for a deal.

In August, Bloomberg reported that BP was looking to sell Gulf assets for $7.9 billion to a group of potential buyers including Royal Dutch Shell ( RDS.A), ExxonMobil ( XOM - Get Report) and Chevron ( CVX - Get Report). The assets being shopped already produce roughly 59,500 barrels a day and hold a reported 120 million barrels of oil in production reserves.

"While these assets no longer fit our business strategy, the Gulf of Mexico remains a key part of BP's global exploration and production portfolio and we intend to continue investing at least $4 billion there annually over the next decade," said Bob Dudley, BP's chief executive.

BP, which has the largest deepwater presence in the Gulf of Mexico of any oil major, is to concentrate its regional presence around production hubs tied to its Thunder Horse, Atlantis, Mad Dog and Na Kika oilfields, some of the most successful finds in the Gulf.

In total, BP has now sold over $30 billion in assets since its Gulf spill, putting the British oil giant on track in its spill-related fundraising.

Plains Exploration and Production, a mid-sized oil driller with significant operations in the Gulf has a smaller financial war chest than the likes of Chevron and is paying a smaller than initially reported price tag.

In a separate deal, Plains said it would buy Shell's working interest in the Holstein Field for $560 million, putting its deals total on Monday over $6 billion.

BP had sold over $24 billion in assets, and $10 billion in oil exploration and production assets, according to data compiled by Bloomberg through the end of 2011. BP's largest announced deals are a set of July 2010 asset sales in Western Canada and the Permian Basin to Apache ( APC).

Still, the oil giant has run into problems as it looks to sell non-core assets and put the April 2010 Macondo oil spill behind it.

In November, BP saw a $7.1 billion deal to sell a majority 60% stake in an Argentinean oil venture called Pan American Energy fall through when its partners, Bridas of Argentina and CNOOC ( CEO) of China, objected to negotiations. The move was a hit to BP, which in October announced it would raise $45 billion through divestitures by 2013.

After CNOOC and Bridas walked away from BP's Pan American sale, the company indicated in a statement that it would be "happy to return to long-term ownership" of the assets after its finances improved. In November, BP said that its sale program is focused on eliminating "non-strategic assets and not driven by a requirement to raise cash."

After its Bridas setback, BP returned quickly to the deals table, selling its natural gas liquids business in Canada to Plains All American Pipeline ( PAA) for $1.67 billion.

In mid August, BP said that it would sell its California oil refinery and 800 statewide gas stations to refining giant Tesoro ( TSO) for $2.5 billion, one of two refineries -- the other being Texas City -- that BP has been trying to sell for several years.

Gulf of Mexico M&A activity has picked up in recent years. In 2010, Devon Energy ( DVN) sold Gulf of Mexico assets to BP as part of a $7 billion deal -- a BP acquisition in the Gulf that occurred less than two months before the Macondo well disaster -- as Devon raised capital to focus on shale drilling opportunities, amid a land drilling boom in North America.

In February, private equity giant Apollo Global Management ( APO) bought El Paso's oil exploration and production unit -- which has a presence in the Gulf -- for $7.15 billion as part of the company's merger with pipeline giant Kinder Morgan ( KMI).

Meanwhile, BP investors and analysts were rattled early last week when documents filed by the Department of Justice on Aug. 31 included language saying the DOJ was going to pursue a gross negligence case against BP. Reports earlier this year -- as well as the findings of a government investigation into the Macondo spill -- suggested that a gross negligence case would be difficult for the government to prove, and that the government and BP were moving closer to a settlement. Nevertheless, the environmental fine associated with gross negligence if proven could be four times as much as the fine otherwise, and could reach $21 billion.

Plains Exploration shares were down 8% on Monday morning, while BP shares were trading close to flat.

-- Written by Antoine Gara in New York