U.S. oil giant Exxon Mobil Corp. (XOM) Thursday became the second company in a month to sign a major offshore oil exploration agreement with Russian oil company OAO Rosneft (ROSN.RS), following a similar deal with BP PLC (BP).

The deal is ExxonMobil's biggest new venture in
Russia since it agreed landmark ventures to produce oil and gas off the coast of Sakhalin in Russia 's far east. It shows how Russia is drawing in the expertise of Western oil companies to explore the country's largely untapped coastal waters. Rosneft has little experience in offshore drilling and is keen to access the advanced technology of companies like ExxonMobil and BP.

ExxonMobil and Rosneft will jointly explore the Tuapse Trough area of Russia's Black Sea, an area that could contain around 7.3 billion barrels of oil equivalent, said Rosneft Chairman and Russian Deputy Prime Minister, Igor Sechin, at a press conference on the sidelines of the World Economic Forum annual meeting here.

"ExxonMobil will bring its technology, project execution capabilities and innovation to complement Rosneft's strengths and experience in the region," said the company's Chairman and Chief Executive, Rex Tillerson, in a statement.

"We will build on the successful relationship we have with Rosneft through the Sakhalin-1 project to help meet energy needs in Russia and the wider Black Sea area," he said.

"ExxonMobil technologies will effectively complement Rosneft's experience and resources," said Sechin. "Development of this area will become the springboard for full-scale
Black Sea basin development."

The companies' joint statement didn't give details of the ownership structure of the agreement, or how the cost of exploration will be shared.

In its deal with BP, Rosneft will own two-thirds of the exploration joint venture, but BP will carry the first $2 billion in exploration costs. The companies also made a cross-shareholding agreement that will see BP take an additional 9.5% stake in Rosneft, and Rosneft take 5% of BP.

At 1115 GMT Thursday Rosneft shares were trading slightly up at 247.59 rubles on Russia's Micex exchange.