PACK OFF SYSTEM

A metal-to-metal packoff comprises a seal element 46 with a pair of annular metal sealing lips 52, 54 that are energized, i.e. expanded, into pressure-tight contact with opposed annular metal surfaces of, for example, a wellhead housing and an inner casing hanger by the wedging force of an annular expander mandrel 32a that has a cross-sectional configuration resembling that of a tuning fork with depending legs 72, 74. The legs, actually annular axial flanges, of the mandrel are radially compressed during that wedging-type seal energization action to result in production of bending energy in the legs as well as in the lips of the seal element, which energy maintains the seal lips in pressure-tight engagement with the opposed wellhead and hanger surfaces throughout wide variations in well pressures to which the seal element may be exposed.