A drilling riser running system includes an automated self-aligning system that can detect and correct when two riser joints are not properly aligned prior to contact between the joints. The system can also include a counter-weight load compensating system that can detect contact between riser joints when they are mis-aligned and reduce the effective load to reduce likelihood of damage resulting from the contact.

A downhole apparatus comprises a casing string with a removable plug therein to block flow therethrough. A flow barrier is positioned in the casing below the removable plug and the removable plug and the flow barrier defining a buoyancy chamber therebetween. A debris barrier positioned above the removable plug includes a frangible disk. A stretchable connecting ring is connected to the frangible disk and to the casing.

A downhole apparatus comprises a casing string with a removable plug therein to block flow therethrough. A flow barrier is positioned in the casing below the removable plug and the removable plug and the flow barrier defining a buoyancy chamber therebetween. A debris barrier positioned above the removable plug includes a frangible disk. A stretchable connecting ring is connected to the frangible disk and to the casing.

A downhole apparatus comprises a casing string with a removable plug therein to block flow therethrough. A flow barrier is positioned in the casing below the removable plug and the removable plug and the flow barrier defining a buoyancy chamber therebetween. A debris barrier positioned above the removable plug includes a frangible disk. A stretchable connecting ring is connected to the frangible disk and to the casing.

A downhole apparatus comprises a casing string with a removable plug therein to block flow therethrough. A flow barrier is positioned in the casing below the removable plug and the removable plug and the flow barrier defining a buoyancy chamber therebetween. A debris barrier positioned above the removable plug includes a frangible disk. A stretchable connecting ring is connected to the frangible disk and to the casing.

A generally cylindrical element 10 that is adapted for immersion in water is described. The generally cylindrical element 10 has an outer surface 11 that is in contact with the water in use. The outer surface 11 has at least two rows of repeating shapes 20, for example hexagons 20, provided on the surface 11, where each row of repeating shapes 20 is separated from the other or the adjacent row(s) by a groove arrangement 30. Each shape 20 within a row is separated from the, or each, adjacent shape 20 by at least one groove 30. This configuration of the surface 11 reduces Vortex Induced Vibration (VIV) and/or drag that may act upon the generally cylindrical element 10 when it is immersed in a body of water.

A system for remediating a blockage in a subsea component including a riser extending from a surface vessel, a flexible jumper having an upper end coupled to the riser and a lower end coupled to a subsea component, and a surface system disposed on the surface vessel and including flexible tubing configured to be inserted and advanced through the tubular string and flexible jumper to the blockage.

Embodiments disclosed herein describe cylindrical structures with indents configured to reduce vortex induced vibrations (VIV). For example, the cylindrical structures may be configured to reduce VIV for risers subject to ocean currents.

An offloading system for conveying hydrocarbons from a buoyancy-supported subsea riser to a surface tanker vessel comprises a flexible hose that hangs from the riser structure in a U-shape having first and second limbs. An upper end of the first limb communicates with the riser and an upper end of the second limb terminates in a pulling head for connecting the hose to the tanker. A clump weight acts on a lowermost bend of the hose between the limbs to maintain tension in the limbs. A subsurface holder fixed to the riser structure is arranged to hold the pulling head against the tension in the second limb of the hose when the system is in a standby state. The holder is offset laterally from a central longitudinal axis of the riser structure and a counterweight is positioned to a side of that axis opposed to the holder.

Offshore production systems and methods relating thereto are disclosed. In an embodiment, the offshore production system includes a surface vessel. In addition, the offshore production system includes a closed-loop cooling fluid circulation system extending subsea from the vessel and configured to cool a cooling fluid. The closed-loop cooling fluid circulation system includes a first tendon having an upper end coupled to the surface vessel and a lower end coupled to the seabed. The first tendon is in tension between the upper end and the lower end. The first tendon is configured to flow the cooling fluid from the lower end of the first tendon to the upper end of the first tendon.