U.S. Exxon Mobil and Russia's Rosneft may invest more than $500 billion (312 billion pounds) in a joint venture to explore for oil in the Arctic and Black seas, according to a presentation for analysts in New York on Wednesday.

The presentation, which was webcast, also said that based on 3-D seismic surveys of 20 prospective structures, the Tuapse block in the Black Sea holds an estimated 9 billion barrels of oil reserves.

(Reporting by Douglas Busvine)