Patent ID: 8176985
Filing Date: 2012-05-15
Classification: E21B

Abstract:
1. A drilling rig comprising: a rotating head; a drill string coupled to said rotating head and rotated by said rotating head, said drill string including a drill bit, wherein said rotating head includes a resilient packer and said drill string and tubing, said resilient packer to seal the region between said drill string and said tubing and to transfer rotational energy from said tubing to said drill string; a surface blowout preventer mounted under said rotating head on said rig; an apparatus to pump lower density drilling mud to the bottom of a hole through said drill string and drill bit; a subsea shutoff assembly, said string passing through said assembly, an annulus in said assembly, returning drilling mud to move upwardly through said annulus in said assembly around said string; and a valve connected to said annulus to selectively inject density lowering fluid into said returning mud.