Abstract: A floating/tensioned production system for use in deepwater drilling and production operations generally combining a relatively small tension leg platform with a semisubmersible platform. The semisubmersible platform is provided with a working deck supported above the water surface so that an air gap exists between the working deck and the water surface. The tension leg platform provides a heave-restrained production deck for near-surface wellhead equipment. The production deck is supported above the drill site but beneath the water surface by buoyancy members and held in place by one or more tethers. Most other drilling and production equipment is located on the semisubmersible working deck. A caisson, surrounding the production deck, is used to provide a substantially dry working area. In one embodiment, the caisson is retractably attached to the production deck.

Abstract: An apparatus and method is described for introducing and removing TFL tools from a subsea wellhead assembly. The apparatus includes an elongate member adapted to hold at least one TFL tool, docking hubs for aligning the elongate member with the wellhead, a clamping mechanism or the like for engaging the elongate member with the wellhead and a circulation for circulating fluid within the elongate member and the wellhead to transport the TFL tool between the elongate member and the wellhead. In another embodiment, the apparatus includes at least two elongate members and a diverter located between the elongate members and the clamping mechanism. The diverter permits alternate fluid communication between each elongate member and the wellhead assembly.

Abstract: A method and apparatus for cleaning debris from the interior surfaces of two flowlines, particularly dissimilar sized flowlines, utilizes a crossover flowline, crossover valve, and two bypass flowlines and bypass valves, wherein the bypass flowlines communicate between a respective flowline and the crossover flowline.

Abstract: Apparatus 10 for propelling equipment through a fluid-filled conduit 12, such as a pipeline or oil well tubular. The propulsion apparatus incorporates first and second elements 14,16 adapted to be moved in a first axial direction through the conduit 12 and to resist being moved in the opposite axial direction. The first and second elements 14,16 are connected by a biasing element 18 which is adapted to move the first and second elements 14,16 toward one another in response to increasing the pressure within the conduit 12 and to move the first and second elements 14,16 away from one another in response to decreasing the pressure. By cycling the pressure of the fluid within the conduit 12, the propulsion apparatus 10 propels itself through the conduit 12. In one embodiment, the first and second elements 14,16 are adapted to reverse, on operator command, the direction of permitted travel of the propulsion apparatus 10.

Abstract: A method and apparatus for cleaning debris from the interior surfaces of two flowlines, particularly dissimilar sized flowlines, utilizes a crossover flowline, crossover valve, and two bypass flowlines and bypass valves, wherein the bypass flowlines communicate between a respective flowline and the crossover flowline.

Abstract: A tether for securing a buoyant structure to the ocean floor. The tether includes a cable or a plurality of cables whose weight is at least partially supported by a buoyancy tank.