Patent ID: 6017168
Filing Date: 2000-01-25
Classification: E21B

Abstract:
In a floating offshore drilling vessel having a riser system with an axis extending between the sea floor and the drilling vessel, a telescopic joint in the riser system having a rotary bearing, and a plurality of riser tensioners extending from the drilling vessel to an outer barrel of the joint for exerting an upward force to apply tension to the riser system, the rotary bearing comprising:a first annular member which engages the outer barrel of the telescopic joint, the first annular member being nonrotational relative to the outer barrel;a second annular member slidingly engaging the first annular member, the first and second annular members being rotatable relative to each other and axially movable relative to each other for a limited amount; anda sealed chamber located between the first annular member and the second annular member and defined by a downward facing portion of the first annular member and an upward facing portion of the second annular member, the chamber containing hydraulic fluid to provide a fluid cushion for allowing the second annular member to rotate relative to the first annular member while the second annular member exerts an upward force on the first annular member through the tensioners.