Abstract: Various wellhead assemblies are provided. In one embodiment, the wellhead assemble includes a seal assembly that seals against an inner surface of a wellhead hanger and against an inner surface of a wellhead body. The wellhead hanger can be sized such that the upper portion of the hanger has an outer surface that abuts an inner surface of the wellhead.

Abstract: A drilling and production system is provided. In one embodiment, such a system has a plurality of functions that are effectuated at least predominately without hydraulic fluid. The system can be a drilling system having a rig (20) and a subsea stack (14) for performing various drilling functions, in which a majority of the drilling functions are effected electrically without hydraulic control fluid. In another embodiment, the rig is coupled to a subsea wellhead assembly (14) but is not connected so as to provide hydraulic control fluid from the rig to the subsea wellhead assembly to enable drilling functions of the subsea wellhead assembly. Additional systems, devices, and methods are also disclosed.