The present invention refers to a method of drilling a marine wellbore with fluid reverse circulation without using drilling riser tubulars. In reverse circulation drilling, the fluid return with gravels occurs inside the drill string (17) and the injection of clean fluid is done through the annular of the well, so that, having a rotating head over the BOP (19), or inside it, the use of riser tubulars as a flow line for the fluid return with gravels is disposed, using instead the drill string (17).

For the kill and choke lines, as well as for fluid injection, rigid or flexible lines can be used, eliminating the need to use drilling risers, thus releasing large load capacity and space on the probe. The method of this invention also eliminates the need for large volumes of fluid to fill entire riser tubulars. The entire operation can be done without the need for subsea pumps or concentric columns. Additionally, the invention makes the operation of lowering the drilling riser tubulars unnecessary, which lasts for days and has a high cost. Finally, for dual activity probes, the arrangement allows the use of the two towers even after connecting the BOP (19), something that is not possible with the use of drilling riser tubulars. Therefore, operations such as mounting and lowering the casing in the water depth can be carried out in parallel with the drilling of the phase, allowing a significant additional gain of time.

An offshore well-processing system includes a mobile offshore drilling unit and a remote well-processing device configured to be positioned on an offshore platform different from the mobile offshore drilling unit, the mobile offshore drilling unit defining at least one well centre and comprising at least one primary drill rig including at least one drill floor and at least one hoisting system for raising and lowering tubular equipment through the at least one well centre from/into a well in the seafloor. The mobile offshore drilling unit and the remote well-processing device are configured to be operationally coupled to each other; and the mobile offshore drilling unit is configured to assist in performing concurrent well-processing tasks on respective wells, including the first well processing task performed by the remote well-processing device on a first well and a second well-processing task concurrently performed by the offshore well-processing system on a second well.

An offshore well-processing system includes a mobile offshore drilling unit and a remote well-processing device configured to be positioned on an offshore platform different from the mobile offshore drilling unit, the mobile offshore drilling unit defining at least one well centre and comprising at least one primary drill rig including at least one drill floor and at least one hoisting system for raising and lowering tubular equipment through the at least one well centre from/into a well in the seafloor. The mobile offshore drilling unit and the remote well-processing device are configured to be operationally coupled to each other; and the mobile offshore drilling unit is configured to assist in performing concurrent well-processing tasks on respective wells, including the first well processing task performed by the remote well-processing device on a first well and a second well-processing task concurrently performed by the offshore well-processing system on a second well.

The present invention relates to methods and systems for establishing a well foundation as well as for drilling and installation of a surface casing without any use of a drilling rig.

The present invention relates to methods and systems for establishing a well foundation as well as for drilling and installation of a surface casing without any use of a drilling rig.

An offshore production system includes a surface vessel, a tubular tendon extending between the surface vessel and a lower connection system disposed at a seabed, the riser coupled to the surface vessel with an upper connection system, and an electrical cable extending through a central passage of the tubular tendon, wherein the upper connection system comprises a connector that physically supports the electrical cable.

An offshore production system includes a surface vessel, a tubular tendon extending between the surface vessel and a lower connection system disposed at a seabed, the riser coupled to the surface vessel with an upper connection system, and an electrical cable extending through a central passage of the tubular tendon, wherein the upper connection system comprises a connector that physically supports the electrical cable.

A semi-submersible floating offshore vessel has a deckbox structure with a main deckbox bottom extending underneath a lower deck. The deckbox structure includes a recessed cellar deck structure that protrudes below the main deckbox bottom, which recessed cellar deck structure has a cellar deck bottom wall that is closed and wave impact resistant and which recessed cellar deck structure has a peripheral wall that is closed and wave impact resistant. The peripheral wall extends between an outer perimeter of the cellar deck bottom wall and the main deckbox bottom of the deckbox structure. The moonpool extends through the recessed cellar deck structure. Seen in plan view, the recessed cellar deck structure includes a number of pointed wave crest splitting sections.

A semi-submersible floating offshore vessel has a deckbox structure with a main deckbox bottom extending underneath a lower deck. The deckbox structure includes a recessed cellar deck structure that protrudes below the main deckbox bottom, which recessed cellar deck structure has a cellar deck bottom wall that is closed and wave impact resistant and which recessed cellar deck structure has a peripheral wall that is closed and wave impact resistant. The peripheral wall extends between an outer perimeter of the cellar deck bottom wall and the main deckbox bottom of the deckbox structure. The moonpool extends through the recessed cellar deck structure. Seen in plan view, the recessed cellar deck structure includes a number of pointed wave crest splitting sections.

A semi-submersible drilling vessel has a deckbox structure, one or more pontoons, and multiple support columns extending upward from the one or more pontoons and supporting thereon the deckbox structure. An annular riser joints storage caisson extends downwardly from the deckbox structure, wherein the storage caisson delimits an annular storage space configured for storage therein of an annular array of riser joints in vertical orientation thereof. A riser joints carousel device is provided in the annular storage space, which riser joints carousel device is configured to carry an annular array of riser joints in vertical orientation thereof in a mobile manner relative to the annular storage caisson so that the array of riser joints is movable along an annular path through the storage spaced between the inner and outer wall of the storage caisson. The deckbox structure is provided with a riser joint transfer passage at a riser joint transfer location above the annular path of the riser joints carried by the riser joints carousel device through the storage space. The vessel is provided with a riser joint vertical transfer device configured to lift and lower a riser joint out of and into the riser joints carousel device, passing therein vertically through the riser joint transfer passage of the deckbox structure.