Oil prices slumped up to nearly 8% to the lowest in more than a year on Friday, posting the seventh consecutive weekly loss, amid intensifying fears of a supply glut even as major producers consider cutting output. Oil supply, led by U.S. producers, is growing faster than demand and to prevent a build-up of unused fuel such as the one that emerged in 2015, the Organization of the Petroleum Exporting Countries is expected to start trimming output after a meeting on Dec. 6.