Rotating drilling head with spaced apart seals

Abstract

A drilling head has a body which lands in an external housing. The body is removably secured to the housing with an annular split ring which is moveable in response to a cam member. The body has an outer body and a rotatable inner body with an axial bore. An annulus extends between the inner and outer bodies. Inlet and outlet ports communicate hydraulic fluid to the annulus which is sealed. The inner body has a gripping member with inner and outer portions. The inner portion has a solid annular elastomer which is free to slide radially relative to the inner body. The outer diameter of the inner portion abuts the outer portion. The outer portion has an energizable elastomer with an annular cavity. The cavity communicates with the annulus through a passage. A primary seal extends from a lower end of the inner body. The seal has a conical elastomer and reinforcement webs to give the elastomer greater rigidity in the upward direction. Drill pipe having a plurality of tool joints is lowered through the bore of the drill head. As tool joints are lowered through the primary seal, the elastomer and ribs flex outward. As the tool joints exit the primary seal, it snaps back and seals around the drill pipe. During drilling, the gripping member is energized to grip and provide a secondary seal around the drill pipe, thereby causing the inner body to rotate with the drill pipe.