U.S. oil refiners hunting to replace storm-lost U.S. Gulf of Mexico crude have been turning to Iraqi and Canadian oil, while Asian buyers have been pursuing Middle Eastern and Russian grades, analysts and traders said.

Royal Dutch Shell, the largest producer in the U.S. Gulf of Mexico, this week said damage to an offshore transfer facility will limit Mars sour crude supplies into early next year. The Mars sour grade of U.S. oil is used heavily by U.S. Gulf refiners and companies in South Korea and China, two top destinations for U.S. crude exports.