Abstract: A blowout preventer assembly comprising an annular blowout preventer having an annular packing unit and an actuator operable to reduce the internal diameter of the annular packing unit, wherein the assembly further comprises a stripping sleeve having a tubular elastomeric sleeve which in use is positioned generally centrally of the packing unit so that the packing unit surrounds at least a portion of the elastomeric sleeve.

Abstract: A method of drilling a subterranean bore hole comprising a) pumping a drilling fluid down a drill string, the drill string having a drill bit at an end thereof, b) rotating the drill string about its longitudinal axis to that the bit forms bore hole in the ground, the method further comprising the steps of: c) changing the rate of pumping of the drilling fluid into the drill string in response to a change in the speed of rotation of the drill string, and/or changing the speed of rotation of the drill string in response to a change in the rate of pumping of the drilling fluid into the drill string.

Abstract: A method of drilling a subterranean well bore using a tubular drill string, the method including the steps of injecting a drilling fluid into the well bore via the drill string and removing said drilling fluid from an annular space in the well bore around the drill string via a return line, wherein the method further includes oscillating the pressure of the fluid in the annular space in the well bore, and monitoring the rate of flow of fluid along the return line.

Abstract: A drilling system (10) including a drill string (13) which extends from a floating drilling rig to a well bore, and a tubular riser (12) which surrounds at least part of the portion of the drill string (13) between the well bore and drilling rig, the riser (12) having a telescopic joint (20) between a first tubular portion and a second tubular portion of the riser, the first tubular portion extending down to a well head at the top of the well bore and the second tubular portion extending up towards the drilling rig, the telescopic joint (20) comprising an inner tube part (20b) which is mounted within an outer tube part (20a), the drilling system (10) further including a riser closure device (26) which is mounted in the second tubular portion of the riser (12) and which is operable to provide a substantially fluid tight seal between the riser (12) and the drill string (13) whilst permitting the drill string (13) to rotate relative to the riser (12).