The crash and explosion of a helicopter carrying a Christmas-week work crew to a Gulf of Mexico oil platform claimed a 15th life, a rig worker who had suffered burns over 95% of his body. Anthony Fann, 23, of Destrehan, La., died at West Jefferson Hospital near New Orleans, a hospital spokesman said. All the others aboard the helicopter--12 other rig workers and two pilots--died Monday. The bodies of the other victims, left on the rig overnight because of poor flying conditions, arrived by helicopter in Lafayette, La., and were taken to the Lafayette Parish Forensic Laboratory for identification. Families of the victims gathered at a nearby hotel suite provided by Penrod Drilling Co., owners of the rig.