As many as six Very Large Crude Carriers are loading and due to load crude oil for export at the Louisiana Offshore Oil Port, Reuters reports , citing unnamed sources in the know. The cargoes will be all medium sour grades, which have become increasingly popular among refiners. The reason heavier graders are becoming increasingly popular is a shortage of heavy crude on global markets caused by falling production in sanction-bound Venezuela and Iran. Cuts in heavy crude production among OPEC members under the December 2018 production cut agreement also contributed to tighter supply. One heavy crude grade in the U.S.—Mars Sour, which is produced in the Gulf of Mexico—traded at a premium of as much as US$4.40 to the benchmark contract at the start of this week, Reuters noted. “We’ve seen very good global demand for medium and heavy sour crude oil,” a Mercuria oil trader told Reuters. […]