Importance

Loading Importance Indicators...

Abstract

An apparatus and method are provided for controlling hydrostatic pressure in drilling fluid in a subsea well. A main pump forces drilling fluid down the drill pipe, out of the end of the drill pipe, and upward in an annulus surrounding the pipe. A rotating drilling head is attached to a wellhead assembly at the sea floor. The drilling head has an inner body rotatably carried in an outer body landed in a bore of a housing. An energizable gripper in a bore of the inner body grips an outer surface of the drill pipe. The drilling head diverts the drilling fluid into a lateral passage in the sidewall of the housing. An auxiliary pump forces seawater through a venturi into a conduit, creating a lower pressure to draw drilling fluid into the conduit to be carried back to the surface vessel. Pressure and flow rate measurements are sent to a control system that modulates the speed of each pump to control hydrostatic pressure.

Loading the Abstract Image...

First Claim