Booming refinery profits are helping Nigeria and other West African oil producers sell cargoes quickly, aided by a shortage in certain types of crude amid OPEC production cuts and Venezuelan troubles, Reuters reports.

A fight for sour crude has helped keep Angolan oil in high demand and now, even long-suffering Nigerian grades are finding keen buyers in the United States and Asia as refineries run full steam on strong margins.

The sour strength is also boosting Nigerian oil, which has a lower sulphur content and produces more fuels such as petrol. Light crudes suffered because most production additions this year, from U.S. shale, Libya and Nigeria, were light crude. But the sour shortage led some buyers to shift to light oil.

Competition among buyers has boosted offers for Nigeria’s Forcados to as much as $1.70 above dated Brent, while offer levels climbed for nearly all other grades. The cargoes are also selling smoothly, in contrast to recent months in which they lingered well after the programmes were issued.