Well blowout preventer, and packing element

Abstract From the Canadian patent

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 at least three, and typically four, 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.