A method is provided for removing an abandoned marine platform from a seabed. The platform extends below the seabed mud line. In order to remove the platform, a frame is provided having a perimeter that surrounds an open center. The frame is lowered over the platform wherein the platform occupies the open center portion. A movable cutter cable is fitted to the frame. At least a part of the cutter cable is positioned below the mud line. The cutter is moved relative to the frame to cut the platform below the mud line. Such movement can be a back and forth movement wherein the cutter cable moves in a first direction, stops and then moves in a second direction that is generally opposite the first direction. A lifting device can employ two vessels and two frames, each frame bridging from one vessel to the other. Winches on the vessel can be used to provide movement to the cutter cable. These same winches can take up cable slack as cutting moves from one platform member (e.g. leg, jacket leg, piling, etc) to another.

The invention relates to an operations vessel for the maintenance, installation and/or disassembly of offshore structures, comprising: a hull equipped with ballast means connected to a control system; at least one working platform supported on the hull by means of one or more support elements; and at least one system for coupling to an offshore structure, wherein said coupling system can adopt, at least, a state in which it is coupled to said offshore structure and a state in which it is not coupled to said offshore structure. Advantageously, the control system and the coupling system are configured in a cooperating manner, in order to adopt at least two working positions of the vessel, wherein the hull adopts an above-water state with the coupling system decoupled, and at least a second working position wherein the hull adopts a submerged state in which the coupling system is coupled to the offshore structure.

A method includes mounting a first jacket connector block (400) to an apparatus. The first jacket connector block includes a first frame (415), a plurality of first conductor tubes (405) connected to the first frame, a first plurality of releasable connectors (420) coupled to first ends of the first conductor tubes, and a second plurality of releasable connectors (420) coupled to second ends of the first conductor tubes and engaging the apparatus.

The present invention relates to a gravity based structure 5 with a topside 2 on at least one hollow concrete platform leg 1 with a platform leg wall and a circular cross section. The at least one platform leg, includes an upper leg portion (4) cut off from a lower leg portion 3. The lower leg portion 3 has an upper sloped cut surface 10 inclined at an angle in the range of 1°-10° off a horizontal axis. The upper leg portion 4 has an upper leg sloped cut surface inclined at the same angle as the lower leg sloped cut surface 10 of the lower leg portion 3 whereby the angles are complementary, the sloped cut surfaces forming an inner and an outer obtuse cone with a common vertical longitudinal axis. Furthermore, the invention relates to method of forming a conical cut through a concrete platform leg of a GBS.

A method includes providing a lower platform block (300) including a first frame (315), a plurality of docking tubes (305) connected to the first frame, and a plurality of first conductor tubes (310) connected to the first frame. At least a first jacket connector block (400) including a second frame (415) and a plurality of second conductor tubes (405) connected to the second frame is releasably coupled to the lower platform block to align the second conductor tubes with the first conductor tubes. A platform deck block (500) including a third frame (515) defining a deck and a plurality of third conductor tubes (505) connected to the third frame is releasably coupled to the first jacket connector to align the third conductor tubes with the first conductor tubes.

A method includes providing a lower platform block (300) including a first frame (315), a plurality of docking tubes (305) connected to the first frame, and a plurality of first conductor tubes (310) connected to the first frame. At least a first jacket connector block (400) including a second frame (415) and a plurality of second conductor tubes (405) connected to the second frame is releasably coupled to the lower platform block to align the second conductor tubes with the first conductor tubes. A platform deck block (500) including a third frame (515) defining a deck and a plurality of third conductor tubes (505) connected to the third frame is releasably coupled to the first jacket connector to align the third conductor tubes with the first conductor tubes.

A foundation for a subsea assembly is provided. The foundation includes connection points. The connection points permit other components to be connected to the foundation and permit loads to transfer from the other components into the foundation. The foundation may be a suction anchor. A method of converting an exploration well using the foundation to a production well is also provided.

A foundation for a subsea assembly is provided. The foundation includes connection points. The connection points permit other components to be connected to the foundation and permit loads to transfer from the other components into the foundation. The foundation may be a suction anchor. A method of converting an exploration well using the foundation to a production well is also provided.

System for transporting an offshore structure, the system comprising: a transport apparatus, in particular a vessel or a vehicle, which is configured to receive an offshore structure and to form a slip joint with a slip joint section of a received offshore structure, wherein the system is configured to enter a releasable state, from a fixing state, wherein, in the releasable state, the slip joint formed by the transport apparatus and the offshore structure is smaller than that force in the fixing state.

A method includes mounting a platform deck block to a tower. The platform deck block (500) includes a first frame (515) defining a deck, a plurality of first conductor tubes (505) connected to the first frame, a first plurality of releasable connectors (520) coupled to the first conductor tubes, and a plurality of docking receptacles (800A,800B,800C) defined in the deck. The tower includes a second frame (415), a plurality of second conductor tubes (405) connected to the second frame, and a second plurality of releasable connectors (420) coupled to the second conductor tubes and engaging the first plurality of releasable connectors coupled to the first conductor tubes. The method further comprises mounting a first production block (600) to one of the plurality of docking receptacles.