Independent Rosneft subsidiary Neftegaz America Shelf acquired a 30 percent stake in 20 blocks in the Gulf of Mexico. Exxon retains a 70 percent stake and stays on as the operator.
Exxon said the 20 blocks cover about 174 square miles in the Gulf of Mexico. Water depths range from 2,100 feet to 6,800 feet. No reserve estimate was declared.
Rosneft President Igor Sechin said the deal gives his company a solid foundation in one of the most prolific natural resource areas in the world.
"We believe joint efforts of our companies will ensure the most efficient development of these blocks, with application of the latest technologies and adhering to high environmental standards," he said in a statement.
The acquisition was covered under the terms of a strategic cooperation agreement signed in 2011. Last year, Exxon and Rosneft signed a deal that included development in areas of the Black Sea and the South Kara Sea in the Russian arctic.
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