The gold rush is on in Texas, and Big Oil is scrambling for a piece of the action. : The oil industry is shelling out billions of dollars in a series of acquisitions in the Permian Basin, the hottest oilfield in the world. The latest deal came on Tuesday when Diamondback Energy (FANG) agreed to purchase shale producer Energen (EGN) for $9.2 billion, forming one of the largest players in the Permian. Late last month, BP (BP) inked a $10.5 billion deal to buy oil assets in Texas.