Apparatus for use in lowering casing strings

摘要

An apparatus for use in lowering casing strings or other parts from a floating unit to a subsea well which includes an expansion-type casing running tool employing extendible latches that have left-handed threads cut on their exterior for engagement with similar threads on the inside of the casing which is to be lowered. Tapered blocks are spring loaded for expanding the dogs into position and hydraulic pressure is used to retract the blocks thus disengaging the running tool from the equipment just lowered. If disengagement of the latches is not accomplished, the running tool can be removed from the casing by left-handed rotation.