A method of positioning an end of a pipeline on a subsea structure includes the steps of: (a) providing a channel on the subsea structure, the channel having an open end adjacent to a receptacle on the subsea structure, (b) providing a pipeline, (c) attaching a connector to an end of the pipeline, (d) laying the end of the pipeline with the connector attached into the channel, and (e) pulling the pipeline end along the channel such that the connector exits the open end of the channel and is received by the receptacle. A channel is used in the method and a subsea structure is used wherein the channel is provided on the upper surface of the subsea structure.

A method approximates and connects an off shore riser duct to a floating unit, includes installing a tubular coupling recipient on the floating unit at a riser coupling level, the coupling recipient having an annular side wall extending around a longitudinal axis. A pulling device is on the floating unit at a pulling device level above the riser coupling level. The pulling device pulls a line extended through the coupling recipient and connected to a pulling head at a riser duct upper end. The riser duct upper end is pulled into the coupling recipient, providing a locking mechanism to lock a coupling adapter against downward withdrawal. Extending the line along a curved deviating surface deviates the pulling direction. The curved deviating surface is formed by a deviating member connected to the coupling recipient at a distance from the longitudinal axis smaller than an annular side wall to longitudinal axis distance.

Disclosed is a single-upright-column mooring type wellhead production operation platform, comprising an upright column body, a positioning and mounting assembly, a rotating table, an oil extraction operation platform and at least one inner well slot, wherein the upright column is of a hollow structure; the positioning and mounting assembly is arranged at a bottom of the upright column body; the rotating table is arranged outside the upright column body, is rotatable around an axis of the upright column body and comprises a mooring connection apparatus; the oil extraction operation platform is arranged on the top of the upright column body and is located above the rotating table, and the oil extraction operation platform is provided with an oil extraction operation assembly; and the inner well slot is arranged in the upright column body and can be connected to the oil extraction operation platform. The platform can adapt to an economic index of extraction of a marginal field. Disclosed are a single-upright-column wellhead production operation platform and a rotary mooring conveying system for oil-producing operation at the same time.

A technique facilitates controlling barrier fluid via a mechanical pressure regulation system which may be coupled with a rotating machine at a subsea location. The mechanical pressure regulation system enables controlled supply of the barrier fluid to the rotating machine and comprises a mechanical valve mechanism. The mechanical valve mechanism automatically maintains a pressure differential between the barrier fluid and a process fluid within a desired range. According to an embodiment, the mechanical valve mechanism is mechanically actuated via pressures applied to a pilot piston so as to provide barrier fluid to the rotating machine when the pressure differential reaches a lower limit and to dump barrier fluid when the pressure differential reaches an upper limit.

A tensioning system includes a combined rope gripper and tension cylinder. A rope passes through the combined rope gripper and tension cylinder. Once the length and/or tension of the rope has been adjusted, a reel lock handle can be actuated to prevent further rotation of the reel. The combined rope gripper and tension cylinder can be actuated to hold the rope. The combined rope gripper and tension cylinder can also be actuated to reduce or prevent the release of tension in the rope.

An adapter assembly for connecting a flowline which includes an end portion to a subsea tree which includes a fluid line connector. The adapter assembly includes an adapter base, a first connection element which is connected to the adapter base and which connects to the fluid line connector of the subsea tree, and a flowline connector assembly which includes a second connection element which connects to the end portion of the flowline. The flowline connector assembly is attached to the adapter base. The adapter assembly connects to the subsea tree via the first connection element.

Disclosed is a single-upright-column mooring type wellhead production operation platform, comprising an upright column body, a positioning and mounting assembly, a rotating table, an oil extraction operation platform and at least one inner well slot, wherein the upright column is of a hollow structure; the positioning and mounting assembly is arranged at a bottom of the upright column body; the rotating table is arranged outside the upright column body, is rotatable around an axis of the upright column body and comprises a mooring connection apparatus; the oil extraction operation platform is arranged on the top of the upright column body and is located above the rotating table, and the oil extraction operation platform is provided with an oil extraction operation assembly; and the inner well slot is arranged in the upright column body and can be connected to the oil extraction operation platform. The platform can adapt to an economic index of extraction of a marginal field. Disclosed are a single-upright-column wellhead production operation platform and a rotary mooring conveying system for oil-producing operation at the same time.

A method of connecting a conduit to a subsea structure is provided. In the disclosed method, a tensioning member is provided on the conduit and attached to the conduit at two locations proximate a first end of the conduit. The tensioning member is used to maintain a curvature formed in the conduit between the two locations e.g. by deflecting a portion of the conduit. A first end of the conduit is engaged with a guide assembly provided adjacent to the subsea structure, and tension in the tensioning member is released to adjust the axial position of the first end of the conduit to enable direct connection between the conduit and the subsea structure. A method of disconnecting a conduit from a subsea structure, and a system for connecting a conduit to a subsea structure are also provided.

A technique facilitates controlling barrier fluid via a mechanical pressure regulation system which may be coupled with a rotating machine at a subsea location. The mechanical pressure regulation system enables controlled supply of the barrier fluid to the rotating machine and comprises a mechanical valve mechanism. The mechanical valve mechanism automatically maintains a pressure differential between the barrier fluid and a process fluid within a desired range. According to an embodiment, the mechanical valve mechanism is mechanically actuated via pressures applied to a pilot piston so as to provide barrier fluid to the rotating machine when the pressure differential reaches a lower limit and to dump barrier fluid when the pressure differential reaches an upper limit.

A method of conveying a production fluid from an offshore subsea well to an offshore vessel includes deploying an inflatable bladder from the offshore vessel, the inflatable bladder including a bladder valve, and fluidly connecting the inflatable bladder to an offloading port positioned at a seafloor, wherein the offloading port includes a port valve and is in fluid communication with one or more subterranean hydrocarbon-bearing formations. The method further includes opening the bladder and port valves to discharge the production fluid from the offloading port into the inflatable bladder, and thereby resulting in a substantially filled bladder, closing the bladder and port valves, and fluidly disconnecting the substantially filled bladder from the offloading port.