An Iranian exchange has offered investors as much as 6 million barrels of oil so far this year. Only a single deal closed, for the minimum 35,000 barrels. Iran’s oil production and exports have slumped after the U.S. reinstated sanctions last year, and new curbs are set to further restrict its exports. Exemptions for importing countries including Japan, China, Turkey, India and South Korea have partially cushioned the blow. With foreign investors steering clear of the world’s fourth-largest holder of crude, it’s trying via the Iran Energy Exchange to offload some oil to domestic buyers. Sales have been dismal, and even Iranian oil officials concede that the physical contracts are undesirable as long as oil sanctions remain intact. “We knew from the beginning that it was almost impossible to sell oil” on the exchange, Morteza Behrouzifar, deputy head of the Iranian Association for Energy Economics, said in an interview. […]