Abstract: A seal useful for high temperature and high-differential pressures, particularly in sour gas wells, is disclosed. The preferred embodiment of the seal is an elongated member having features akin to a chevron-type seal at at least one end, coupled with at least one interference seal. A pocket is created in between these two elements which can trap atmospheric pressure, thereby enhancing the ability of downhole well fluids to compress the seal against a mandrel for facilitating its installation in a liner bore. The additional structural rigidity provided by the variety of alternative designs presented overcomes the tendency of the chevron portion of the seal to fail to seat due to downhole fluid pressures, displacing the chevron portion out of shape prior to its insertion into a liner bore.