OPEC and Russia will need to prolong their six-month deal to cut oil output if they plan to trim the global inventory glut that has kept a lid on prices, said Total SA Chief Executive Officer Patrick Pouyanne. “If they want really to have an impact on the market, which means to have the inventories going down because inventories are quite high, it will have to be extended beyond May,” Pouyanne said Tuesday in a Bloomberg television interview in New York.