Exxon Mobil has agreed to pay $650 million for Petrohawk Energy Corp.’s natural gas wells and pipelines in the Fayetteville Shale, Arkansas. Exxon Mobil will pay $575 million for the Fayetteville upstream assets and $75 million for midstream assets. The deal is the second shale purchase by Exxon in 2010, and is expected to close early in 2011. Texas-based Exxon acquired XTO Energy in June of 2010 for $35 billion.