ultra large crude carrierultrasonic sounderultraviscosonunconformable bedunconsolidated formationuncontaminated zoneundercutundergage holeunderground gasificationunderground lineunderground line locatorunderground resevoirunderramerunexploited bedunexploited fieldunguyed mastunload v the bitunmanned submersibleunpenetrated bedunproven areaunrecoverable oil reservesunsaturated hydrocarbinunspecified wellunsteady flowunworkable depositup dipup structureupper jurassicupper permianupper triassicupper valveupset pipeupset tubingupward stroke