Riser set-aside system

摘要

A marine riser system for use in deep water drilling operations from a floating vessel is disclosed. The riser system permits detachment of the lower end of the riser from the wellhead enabling the riser to be set aside to a position which is clear of the wellhead. Support means adjacent the wellhead can be used to support and position the riser when it is set aside. Tensioners, support mechanisms and guidance means are provided to move the riser back and forth between the wellhead and support means. In this manner, casing and tools having diameters larger than that of the riser can be inserted into the wellhead without returning the riser to the surface. Drilling operations with large diameter drill bits can also be conducted with the riser in the set aside position.