 Shares of Whiting Petroleum Corp. WLL, 5.67 surged 4.9 and Oasis Petroleum Inc. OAS, 8.18 rallied 5.6 in premarket trading Monday, after the oil and gas production companies announced a merger of equals that will value the combined company at about 6.0 billion. Under terms of the deal, Whiting shareholders will receive 0.5774 shares of Oasis common stock and 6.25 in cash for each Whiting share they own. 