Abstract: A barge (14) that stores liquid hydrocarbon (oil) from a producing facility (12) and offloads it perhaps once a month to a shuttle taker (40), is constructed for unmanned operation except during the once-per-month unloading. The barge has a permanent nonadjustable ballast (53, 54, 55) and has a solar powered system for communication with a central center for normal operation and emergency shutdown. The barge avoids a “hotel system” for a permanent crew (up to 50 people) by avoiding seawater ballast tanks, ballast pumps and related systems. The only person-operated equipment is an engine-generator set (142) and pumps (44), to be operated only during offloading for perhaps 3 days every month. The barge is unpowered except by solar energy or batteries, and is left unmanned except during offloading, so only temporary crew quarters are provided. The barge has a tank assembly (57) with rows of tanks connected in series so oil can be loaded and unloaded from the frontmost tank in each row.

Abstract: An offshore hydrocarbon production system includes a spar (34, 52, 214) that floats at the sea surface, a subsea buoy (26, 154, 200, 210) lying under the spar and hanging from it, and one or more risers (20, 174, 220) that extend up to the subsea buoy and are coupled therethrough to the spar. The subsea buoy is initially negatively buoyant to ballast of the spar and keep it upright, but the subsea buoy can be made positively buoyant so the spar can be moved away and a workover vessel (70) moved over the subsea buoy. The subsea buoy can be coupled to the spar by one or more chains (60, 60A) extending between them, and one or more flexible hoses (60) extending between them.

Abstract: An offshore system is described, of the type that includes a turret (20) anchored to the sea floor and connected by at least an upper bearing assembly (34) to the vessel hull (14) so the hull can weathervane about the turret, wherein the upper bearing assembly is of moderate cost and high reliability, is easily maintained, and accommodates vessel hull deformation. The upper bearing assembly includes a circle of bearing devices(202) wherein each device includes a cylinder (224) and piston (226). A source (260) of pressured fluid is applied to the devices to push apart the cylinder and piston to support an upper bearing part (204) of the turret on a lower bearing part (210) of the hull.

Abstract: An offshore system is provided of the type that includes riser pipes (30) extending up from the seafloor (44) to a tall and narrow caisson (12) at the sea surface, with the caisson moored by mooring lines (34) extending to the seafloor and anchored thereat, which minimizes bending of the upper portion of the riser pipes when the caisson drifts in severe weather. Although the caisson has a Ballasted lower end and buoyant upper end to keep its axis (20) vertical, a device is provided for applying a horizontal force (54) to a location along the caisson that is vertically spaced from the upper ends of the mooring lines, to tilt the caisson so the axis of the caisson is parallel to portions (82) of the riser pipes lying immediately below the caisson. In one arrangement, a second set of mooring lines (60) is provided, that have upper ends coupled to second locations (64) along the caisson that are vertically spaced from the upper ends of the first mooring lines.

Abstract: A system is provided for securing a vessel (24) such as a tanker to a moored body (12) that is moored to the sea floor, which enables the vessel to remain secured in more severe weather. In addition to the deployed length (27) of securing line (26) that extends between the moored body and the vessel, applicant stores an additional length (28) of securing line. When large drift forces are applied to the vessel, the vessel is allowed to drift away from the moored body, while a braking apparatus (34) pays out the previously-stored length of securing line, while resisting such pay out by maintaining a high securing line tension such as 300 tons. When the drift force decreases to a predetermined low level such as 60 tons, the braking apparatus draws in the securing line to draw back the vessel towards its quiescent position.

Abstract: An offshore system is described, of the type that includes a turret (20) anchored to the sea floor and connected by at least an upper bearing assembly (34) to the vessel hull (14) so the hull can weathervane about the turret, wherein the upper bearing assembly is of moderate cost and high reliability. In one construction, the upper bearing assembly includes upper and lower slider bearing rings (40, 42) that lie facewise adjacent at an interface (44), with the upper bearing ring fixed to the turret and the lower bearing ring supported on the hull through quantities of elastomeric material (102). The elastomeric material permits slight tilt of the turret upper portion without opening a gap at one side of the interface. The lower bearing ring is divided into segments (112A, 112B), and large turret tilt allows pressured lubricant to escape from only one or a few segments that begins to lift up during turret tilt.

Abstract: A fluid swivel arrangement comprising a vertical stack of fluid swivels mounted on a turret of a weathervaning ship, enables a spare fluid swivel to be provided without requiring an additional pipe and consequent larger diameter of fluid swivels. A pair of fluid swivels (53, 54) are provided, with one serving as a spare to be used in the event of failure of the other. A single pipe (94) extends through holes (120) in the swivels and is coupled to the inlet ports (90, 92) of both swivels, so it can direct fluid into either one. A means for controlling flow, enables the flow to be switched to either fluid swivel. The means for controlling flow can include a plug (140) for insertion into the inlet port of one of the swivels, to block the inflow of fluid thereat. The means for controlling flow can also include a valve (130) lying along the pipe between the upper and lower fluid swivels, so when the valve is closed fluid flows only to the lower fluid swivel.

Abstract: An offshore fluid transfer system (10) is provided, of the type that includes a riser (32) having an upper end (34) connected through a universal joint (36) to a turret (22) on a vessel and having a lower end (36) anchored by catenary chains (40), and that also includes hoses (70, 71) extending from a base (50, 58) on the seafloor to the turret on the vessel, which avoids the need for a complicated hose structure to pass fluid across the universal joint. A fluid coupling (73) near the bottom of the turret, which is widely spaced from the universal joint, connects to a hose that extends from the fluid coupling in a sinuous path down to the seafloor base. The long length of hose, enables it to bend when the vessel drifts, to avoid excessive hose tension or riser contact during such vessel drift. A riser connector (102) can be operated to disconnect the riser from the turret so the riser can sink. The fluid coupling can include a fluid connector (100) which can separately disconnect the hose from the turret.

Abstract: A bearing assembly that mounts the lower portion of a rotatable large (at least 4 meters diameter) turret in a moonpool near the center of a vessel, avoids damage resulting from turret and/or vessel deformation in heavy seas, while facilitating initial alignment. The turret (10) holds a substantially continuous bearing ring (44) while a hull part (42) holds a plurality of circumferentially-spaced segment structures (46) that have segment bearings (50) engaged with the bearing ring. Each segment structure includes a base (56), and an elastic body (60) that supports the bearing segment while allowing it to move radially or tilt. A deflection limiter (80) can limit deformation of the elastic body. Each segment structure can include an adjustment device (62) that adjusts the position of the bearing segment during setup.

Abstract: A tension leg platform system includes a relatively small platform (12, FIG. 3 ) and relatively low capacity tendons (16), despite providing sufficient tension to risers (34) that carry hydrocarbons from seafloor wells to the platform. With the platform floating at the sea surface and held in position by the tendons, seafloor wells can be connected through risers to a side of the platform, with the tension of each riser compensated by adding buoyancy to the corresponding side of the platform, as by using pressured air (at 100) to blow water out of a platform compartment (94).

Abstract: An offshore production system of the type that includes a TLP (tension leg platform) (12) and a derrick vessel (14) which moves to the TLP platform (16) whenever the derrick is required. The vessel carries fastener assemblies (131) that rigidly fix the vessel to the platform so they move vertically and horizontally as a single unit, which avoids any need to separately anchor the vessel and which facilitates operation of the derrick in more adverse weather. The vessel preferably has thruster equipment (88) which not only allows it to self-propel itself to the platform, but which also allows the vessel to propel itself and the platform sidewardly, to avoid drift of the platform during drilling. The vessel includes a vessel deck (70) which lies above the platform and a pair of vessel sides (72, 74) with pontoons (76, 78), that lie on opposite sides of the platform.

Abstract: A turret that is rotatably mounted on a vessel and connected to risers extending down to sea floor wells, is constructed so the turret is of moderate diameter to enable the use of a moderate size bearing and moderate weight turret, while providing room around the terminations of the upper ends of the risers. The risers (46A, 46G, FIG. 3 ) extend through tubes (62, 70, 72) which are oriented at an angle to the turret axis (22), so the lower ends of the tubes lie on large diameter circles to be considerably spaced apart, while the upper ends of the tubes are closer together to fit within the inside of the moderate sized bearing (60). The upper ends of the risers may be terminated at a plurality of different levels (90, 92, 94) within the turret to provide room around each termination.

Abstract: An arrangement is described for mounting a turret (18, FIG. 3) on the outer ends of beams, or mounts, whose inner ends are supported by a vessel hull (14) that can weathervane about the turret. An upper bearing (42) is supported on a largely rigid upper mount (30), by a resiliently deflectable support structure (50) that includes a plurality of elastomeric shear pads (52). Each shear pad subtends an angle (B, FIG. 5) of no more than 20.degree. about a common point (26) along the rotatable axis of the turret. This allows a shear pad to use flat rubber sheets instead of spherically curved sheets, as well as avoiding excess stiffness. The support structure includes six posts (54) extending radially from the common point along the turret axis, each post having a gap where a shear pad is mounted, with the area around each shear pad being open to facilitate replacement of a shear pad.

Abstract: An offshore fluid transfer system is described, for transferring fluid between stations (12, 14, FIG. 1) that may be many kilometers apart and lie in deep water, which avoids the need for making fluid connections at great underwater depths. A buoy station (14) includes a buoy (40) anchored to the seafloor to lie a moderate distance below the sea surface, and coupled through a flexible hose (46) to a turret (52) that is attached to a weathervaning vessel (30) and that is anchored to the seafloor. A major conduit portion (34) which extends between the first station and the buoy, includes a long pipeline of series-connected steel pipes that extends along the seafloor to near the buoy station, with an end portion (32) of the pipeline extending in a J-curve and in a primarily upward direction to the underwater buoy.

Abstract: A system is provided for disposal of gaseous hydrocarbons produced from an undersea well, which minimizes the gas disposal cost. The system includes a polymerization station (80) mounted on an anchored floating vessel arrangement (12), which converts the gas to a liquid hydrocarbon that is stored and then transported by a shuttle tanker (52) to a refinery. The liquified gas can be mixed with liquid hydrocarbons originally obtained from the undersea well, both in the shuttle tanker and in storage tanks on the anchored vessel arrangement. Sea water can be used to create steam for the polymerization process.

Abstract: A torque enhancer (60, FIG. 1) is provided for an offshore system wherein a turret (18) is rotatably mounted about a vertical axis (22) on a vessel hull and the turret is anchored by catenary chain devices (24), to help minimize rotation of the turret when the vessel weathervanes. The torque enhancer may include a pair of members (80, 82, FIG. 3) with horizontally-spaced inner ends (84, 86) pivotally mounted on the turret and with outer ends (90, 92) coupled to a chain device (24) to transmit horizontal components (E) of tension force that tend to turn the turret to maintain it at its initial rotational orientation with respect to the seafloor. In one system, the arms are rigid beams arranged to form an A-frame, with the outer ends of the arms supporting a guide (100) and with the chain device slidably extending through the guide and attached to the vessel half way between the inner ends of the beams. In another system, a pair of chains (122, 124, FIG.

Abstract: A fluid swivel is described, of the type that carries oil, water or natural gas at high pressure between an undersea well and a weathervaning ship, which has a seal device of increased lifetime. The seal device (56, FIG. 2 ) lies in a cavity of a first swivel part (12) and includes a rigid seal ring (62) that is slidable toward and away from a sealed surface (66). A deformable seal (60) can be backed up by the seal ring, with the seal ring sliding to close the extrusion gap (70) into which the seal could extrude when high pressure fluid enters the swivel. A pressure source (80) coupled to the cavity urges the backup part to deform radially and slide toward the sealed surface with a force that increases as the pressure of fluid in the swivel increases.

Abstract: A vessel with a rotatable turret thereon is moored in a manner that minimizes turret tilt while avoiding the need to maintain precisely concentric upper and lower turret bearings. A mooring structure (152, FIG. 7) is formed by a group of mooring lines (162, 164) such as chains, with the upper ends of the lines coupled to the vessel through a connecting apparatus (154) that comprises a group of arms (166) each connected to a corresponding one of the lines. Each arm is pivotally mounted (at 170) on the turret to hang therefrom, so the arm transmits primarily vertical forces to the turret and the turret bearing (185) has to support primarily vertical forces. Each arm carries a bearing pad (174) that presses horizontally against a vessel lower bearing ring (182) mounted directly on the vessel hull independently of the turret.

Abstract: A fluid swivel is described, of the type which includes a ring-shaped outer structure (12, FIG. 2 ) that rotates about a ring-shaped inner structure (14), and which form an annular chamber (18) between them and a pair of gap passages (24, 26) between them which are sealed by pressure seals (30, 32). The outer structure includes a body (70) forming part of the annular chamber and a seal ring (72) mounted on an end of the body and abutting one side of the pressure seal. The seal ring is axially shiftable on the end of the body, so that when the body expands radially as a result of high pressure fluid being introduced into the annular chamber, the seal ring does not have to expand a similar amount and therefore does not have to cause a large increase in the width of the extrusion gap (62) at the downstream end of the pressure seal.

Abstract: A fluid swivel, of the type that carries oil, natural gas, or other fluid between an undersea well or pipeline and a weathervaning ship, wherein the seal arrangement that prevents leakage of fluid is constructed to increase the seal lifetime and reduce the cost of the fluid swivel. The seal arrangement includes a recess (44, FIG. 2) in a first of the swivel parts and a seal assembly (46) therein which includes a pressure seal (50) and a backup ring (56). The backup ring has a dynamic side (64) lying adjacent to the portion (54) of the second swivel part that is sealed against, and has an opposite distal edge portion (72). The dynamic side of the backup ring has a tapered downstream portion (80) that is tapered at an angle A of no more than 30.degree. to the axis of rotation (16) of the fluid swivel, with the downstream edge (82) of the tapered portion lying on a downstream wall (86) of the first swivel part rather than overhanging it.