HOUSTON—U.S. oil refiners hunting to replace crude lost after a storm hit the U.S. Gulf of Mexico last month 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 from Hurricane Ida to an offshore transfer facility will limit Mars sour crude supplies into early next year. The grade is used heavily by U.S. Gulf refiners and companies in South Korea and China, the top two export destinations for Mars. The United States generally exports more than 3 million barrels per day (bpd) of oil, most from the U.S. Gulf Coast. With overall fuel demand rebounding to pre-pandemic levels, refiners will need to make up for the Mars shut-ins. The loss of up to 250,000 bpd has some U.S. refiners seeking …