Chevron Corp., Hess Corp. and Continental Resources Inc. had their credit ratings cut by Standard & Poor’s as the worst oil-market collapse in a generation squeezes energy producers. In a sweeping downgrade of some of the biggest U.S. explorers, Chevron’s rating was reduced to AA- from AA, Hess was lowered to BBB- from BBB, and shale driller Continental was cut to junk status, S&P said in a statement on Tuesday. EOG Resources Corp., Apache Corp., Devon Energy Corp. and Marathon Oil Corp. also faced downgrades. The ratings cuts were widely anticipated by oil executives as crude plummeted to prices not seen since the early 2000s, strangling companies of cash needed to fund drilling, pay dividends and service debts.