Exxon Mobil (XOM), the world's largest oil company, will spend up to $300 million on a joint venture to explore the Arctic shelf with Russia's state-owned Rosneft. The pact is part of a larger, long-term agreement signed in August 2011. Under the terms, Rosneft will provide personnel and access to existing infrastructure in western Siberia. Exxon agreed to provide financing, along with exploration and drilling technology, experts and drilling