Well blowout preventer, and packing element

A well blowout preventer packer unit is characterized by long life, and induced back to front (radial) rubber feeding between metallic inserts to close on well pipe or on a well tool for producing a pressure gradient against the pipe or tool which is greatest at the bottom of the packer extent engaging the pipe, and lowest at the top of the packer extent engaging the pipe. The preventer piston has multiple interior frusto-conical surfaces to progressively and sequentially penetrate the packer rubber to effect controlled and enhanced rubber displacement for sealing against the pipe or tool; one of such surfaces is located relatively further from the piston axis than another such surface and has greater angularity relative to that axis than the other surface, and said one surface also has axial projection of greater radial dimension than that other surface.