Abandonment of offshore oil wells

摘要

A method and apparatus for abandonment of an underwater well head which includes a strip of capped concentric casings (36) with at least one casing supported within another casing by a suspension arrangement, comprises explosively severing the casings a pre-defined distance below the mud-line (37). To achieve this one or more caps (38) are removed from a relevant casing or casings by application of rotational torque to the cap and reacting such torque to an outermost casing (39), using a torque reaction tool (40) secured to the top of the casing (39) and having a platform (41) to receive a hydraulic tongs (42). The tongs (42) serve to apply rotational force to the shaft (43) of a tool (44) engaged with the cap with the torque reaction of such force being taken-up by a cable attached between the tongs (42) and the reaction tool (40) and co-acting with abutments (45) so that the torque is transferred to act on the casing (39).