Abstract: A packoff for a casing hanger for a subsea wellhead employs a one piece metal part with ancillary elastomer seals. A C-shaped metal seal links external metal lips. A locking section is located above the packoff. The locking section has a neck that allows it to buckle under sufficient downward force. When it deflects, a primary locking shoulder engages a locking shoulder of the casing hanger. At the same time, a secondary locking shoulder on the outer side of the locking section locks to a shoulder on the outer side to prevent the locking section from moving out of the locked position when an upward test pull is exerted.

Abstract: A wellhead housing has features to increase the load carrying capabilities. The wellhead housing has a inclined load shoulder. A lower casing hanger which supports the outer string of casing is supported on the load shoulder. A landing profile locates between the load shoulder and the casing hanger. The landing ring has a cylindrical portion both above and below the load shoulder. These cylindrical portions restrain the material of the wellhead housing from yielding downward and inward. Also, a support ring encircles the wellhead housing on the exterior radially outward from the load shoulder. The support ring is fitted to the wellhead housing in an interference fit to provide a preload compressive force. Additional casing hangers for intermediate and inner strings are supported on the lower casing hanger.

Abstract: A conical thread configuration for providing a strong simple and rapid make-up connection of pin and box members particularly for connecting sections of pipes, casings and conductor pipes, anchoring pipes, wellheads and risers, particularly for offshore oil production. Each connecting member has a plurality (n) of thread lead entries on a frusto-conical surface, (n) being at least equal to two and at most equal to AD.times.p.times.1/6.25 in which AD is the average diameter of the frusto-conical surface bearing threads (in inches) and p is the number of threads per inch. The radial dimension of the engaged thread overlap after make-up is smaller than the variation VR of the radius of the frusto-conical surface on one thread pitch and larger than 1/2n of variation VR. Less than one turn is necessary for make-up or disconnection.

Abstract: A conductor tieback connector for connecting a conductor to a subsea wellhead includes a downwardly extending funnel. Two bearing rings within the funnel interact with the outside surface of the wellhead to generate bending forces to force the tool in alignment with the wellhead. Thereafter a separate lockdown nut secures the connector to the wellhead without rotation of the conductor.

Abstract: A method of welding the ends of submerged pipes in a gaseous atmosphere at any depth comprises isolating the ends of the pipes by introducing obturators therein and then introducing the pipe ends into an open topped receptacle which is capped with an underwater personal carrying intervention unit. The closed receptacle is filled with gas and then a sleeve is positioned between the ends of the pipes and welded to the pipes.

Abstract: In a method of welding together two submerged pipe ends, the pipe ends are spaced apart and introduced through orifices into a receptacle by which they can be isolated from the surrounding medium. The spaced pipe ends are connected by a connection sleeve and after isolation are welded to the connection sleeve.

Abstract: A plurality of wells are clustered around a central riser which is maintained under tension from a floating platform. A plurality of spiders on the riser carry funnels in vertical alignment with the wells. The funnels are sufficiently large to permit the passage of wellhead connectors and master block valves, and the production risers include centralizers which brace the production riser from the funnels through a limited vertical range. Tensioning of the production riser is with a lower force and through a limited range which precludes disengagement of the centralizers from the funnel. Some centralizers are located to facilitate entry and attachment to the wellhead.

Abstract: A system for welding the ends of submerged pipes in a gaseous atmosphere at any depth comprises isolating the ends of the pipes by introducing obturators therein and then introducing the pipe ends into an open topped receptacle which is capped with an underwater personal carrying intervention unit. The closed receptacle is filled with gas and then a sleeve is positioned between the ends of the pipes and welded to the pipes.

Abstract: In a method of welding together two submerged pipe ends, the pipe ends are spaced apart and introduced through orifices into a receptacle by which they can be isolated from the surrounding medium. The spaced pipe ends are connected by a connection sleeve and after isolation are welded to the connection sleeve.

Abstract: The ends of submerged pipes are connected using a receiver provided with two apertures through which the pipe ends extend, the receiver being adapted to form a watertight enclosure with an intervention unit and housing means for closing the ends of the pipes comprising two stoppers bearing seal means to be applied against the inner walls of the pipe ends and being maintained spaced apart by a first boom, the receiver including means for supporting a sleeve to be connected to the ends of the pipes and a replacement boom located in the sleeve, the connection being performed by introducing the ends of the pipes to be connected into the receiver through the apertures, at least one of the pipe ends being introduced by movement of the receiver relative thereto, closing the ends of the pipes with the stoppers, causing an intervention unit to descend on to the receiver, providing a watertight enclosure therewith, removing the water from the enclosure and placing it under atmospheric pressure, placing the receiver und

Abstract: The ends of submerged pipes are connected using a receiver provided with two apertures through which the pipe ends extend, the receiver being adapted to form a watertight enclosure with an intervention unit and housing means for closing the ends of the pipes comprising two stoppers bearing seal means to be applied against the inner walls of the pipe ends and being maintained spaced apart by a first boom, the receiver including means for supporting a sleeve to be connected to the ends of the pipes and a replacement boom located in the sleeve, the connection being performed by introducing the ends of the pipes to be connected into the receiver through the apertures, at least one of the pipe ends being introduced by movement of the receiver relative thereto, closing the ends of the pipes with the stoppers, causing an intervention unit to descend on to the receiver, providing a watertight enclosure therewith, removing the water from the enclosure and placing it under atmospheric pressure, placing the receiver und