Global Marine, Inc.

Abraham Person

Sherman B Wetmore

James F McNary

Vance E Bolding

Robert C Crooke

Yilmaz H Ozudogru

An ocean thermal energy conversion facility includes a long pipe assembly which is supported at its upper end by the hull of the floating facility. Cold water flows to the facility from deep in the ocean. The pipe assembly comprises an elongate pipe construction and a weight connected to the lower end of the construction by a line of selected length. A floatation collar is connected to the construction at its upper end to cause the construction to have positive buoyancy and a center of buoyancy closer to the upper end of the construction than its center of mass. The weight renders the entire pipe assembly negatively buoyant. In the event that support of the pipe assembly should be lost, as by release of the assembly from the facility hull in an emergency, the assembly sinks to the ocean floor where it is moored by the weight. The pipe construction floats submerged above the ocean floor in a substantially vertical attitude which facilitates recovery of the assembly.

Method of deployment, release and recovery of ocean riser pipes

Apparatus is provided for connecting to a floating structure the upper end of a pipe assembly disposed substantially vertically in an ocean and the like. The pipe can be an upwelling pipe in an ocean thermal energy conversion installation. Gimbal apparatus are coupled between the pipe and the structure concentrically about the pipe. The gimbal apparatus define two orthogonal gimbal axes about which the pipe can move relative to the structure. The gimbal apparatus carry essentially all of the load between the pipe and the structure. Ball joint apparatus are coupled between the upper end of the pipe and the structure to define the boundaries of a path of fluid flow between the pipe and the structure. The ball joint apparatus includes an element associated with the pipe and an element associated with the structure. The ball joint apparatus is centered in the intersection of the gimbal axes.

Connection of the upper end of an ocean upwelling pipe to a floating

Deployment, release and recovery of ocean riser pipes

In an ocean thermal energy conversion facility, a cold water riser pipe is releasably supported at its upper end by the hull of the floating facility. The pipe is substantially vertical and has its lower end far below the hull above the ocean floor. The pipe is defined essentially entirely of a material which has a modulus of elasticity substantially less than that of steel, e.g., high density polyethylene, so that the pipe is flexible and compliant to rather than resistant to applied bending moments. The position of the lower end of the pipe relative to the hull is stabilized by a weight suspended below the lower end of the pipe on a flexible line. The pipe, apart from the weight, is positively buoyant. If support of the upper end of the pipe is released, the pipe sinks to the ocean floor, but is not damaged as the length of the line between the pipe and the weight is sufficient to allow the buoyant pipe to come to a stop within the line length after the weight contacts the ocean floor, and thereafter to float submerged above the ocean floor while moored to the ocean floor by the weight. The upper end of the pipe, while supported by the hull, communicates to a sump in the hull in which the water level is maintained below the ambient water level. The sump volume is sufficient to keep the pipe full during heaving of the hull, thereby preventing collapse of the pipe.

Flexible ocean upwelling pipe

Apparatus for position stabilizing the lower end of an elongate duct, which is vertically disposable in an ocean and which is supported at its upper end, is described. The apparatus includes an elongate flexible tensile member which is disposable along the interior of the duct. The tensile member is adapted to be connected at one end thereof to a duct support structure and to extend through the duct. A weight of selected mass and size is connectible to the other end of the tensile member below the lower end of the duct. Means are connectible between the tensile member and the duct, at least adjacent the lower end of the duct, for establishing and maintaining a selected position of the tensile member relative to the duct.

Stabilization of subsea riser pipes having free lower ends

A long, vertically disposed ocean water upwelling pipe, such as a cold water riser in an ocean thermal energy conversion facility, is fitted at its lower inlet end with a self-cleaning inlet screen. The screen includes a right conical frustum of loose metal netting connected at its larger upper end to the lower end of the pipe. A heavy, negatively buoyant closure is connected across the lower end of the frustum. A weight is suspended below the closure on a line which passes loosely through the closure into the interior of the screen. The line tends to stay stationary as the lower end of the pipe moves, as in response to ocean current vortex shedding and other causes, thus causing the closure to rattle on the line and to shake the netting. The included half-angle of the frustum is about 20.degree. so that, on shaking of the netting, marine life accumulated on the netting becomes loose and falls free of the netting.

Self-cleaning inlet screen to an ocean riser pipe

Apparatus for drilling a well at a location submerged below a body of water includes a buoyant foundation structure. The foundation structure is floatable on the surface of the body of water and is subject to vertical motion in response to waves and the like. A riser handling and tensioning mechanism is mounted to the foundation structure and is operable for moving a riser pipe along a substantially vertical line from and to the foundation into and out of connection with the submerged location. The riser handling and tensioning mechanism is also operable for applying tension to a riser pipe connected to the submerged location. The handling and tensioning mechanism includes vertically disposed hydraulic rams mounted to the foundation structure. Holding means are releasably engageable with a riser pipe adjacent its upper end and are connected to the rams for movement along the riser line by the rams. The rams have an active operating mode in which they are operable to lower and raise a riser pipe along the line into and out of connection of the lower end of the riser with the submerged location. The rams also have a passive operating mode in which they are operable to apply a selected upward force to a riser engaged in the holding means and connected to the submerged location during vertical motion of the foundation structure.

Marine riser system with dual purpose lift and heave compensator

A single-point mooring system is provided for substantially permanently mooring a floating structure, such as an offshore natural gas treatment facility located on a shipform hull, to an anchor point. A rigid anchor structure, fixed to the bottom of the water body, defines a vertically oriented circular cylinder above the water surface. A collar is mounted circumferentially of the cylinder for movement about and along the cylinder. A pair of rigid arms extend from the floating structure in spaced relation to either side of the cylinder and are spaced equally from the roll axis of the floating structure. Resilient connections are coupled between the arms, the floating structure and the collar to locate the collar centrally between the arms in a normal state, to afford and to accommodate motions of the floating structure relative to the collar in horizontal directions and also about the roll axis of the floating structure in surge, sway and roll, and to absorb the forces manifested between the floating structure and the collar in association with surge and sway motion of the floating structure. Pitch, heave and heading change motions of the floating structure are accommodated by motion of the collar relative to the cylinder.

Single-point mooring system

A ship in which a string of heavy pipe is raised or lowered vertically beneath the ship at a substantially constant velocity in spite of heaving movement of the ship. The equipment for raising and lowering the pipe string is supported by the vessel through a heave compensation mechanism that permits vertical movement of the ship relative to the pipe raising and lowering mechanism. The heave compensation mechanism is a passive damped pneumatic-hydraulic spring system for isolating the vertical movement of the ship from the pipe raising and lowering equipment. The spring system operates over a very wide range of load imposed by the raising, lowering and supporting of a very long heavy pipe string.

Heave compensation apparatus for a marine mining vessel

A system utilizing linear hydraulic cylinders for continuously raising or lowering a pipe string. Two sets of cylinders are spaced along the length of the pipe string. The cylinders are driven reciprocally with the cylinders in one set moving out of phase with the cylinders of the second set. Each set of cylinders includes means for releasably supporting the pipe string. The supporting means are operated out of phase so that one is released while the other is supporting the pipe. Control is such that the cylinder sets alternately raise or lower the pipe by incremental amounts, providing a continuous constant motion to the pipe string.

Hydraulically operated heavy lift system for vertically moving a string

A ship in which a string of heavy pipe is raised or lowered vertically beneath the ship at a substantially constant velocity in spite of heaving movement of the ship. The equipment for raising and lowering the pipe string is supported by the vessel through heave compensation means that permits vertical movement of the ship relative to the pipe raising and lowering mechanism. The heave compensation means is a passive damped pneumatic-hydraulic spring system for isolating the vertical movement of the ship from the pipe raising and lowering equipment. The spring system operates over a very wide range of load imposed by the raising, lowering and supporting of a very long heavy pipe string.

A parking brake for subsea mining equipment that is raised and lowered by a pipe string from a surface vessel. The brake assembly is mounted between a pair of linear lift units that alternately grip equally spaced collars on the pipe and move the pipe string in incremental steps. The brake includes a releasable yoke for engaging one of the collars. The yoke is rotatable to permit rotation of the pipe string by the brake assembly. The position of the brake is such that either drive unit may be used to position the pipe string so that a collar is engaged by the yoke of the brake assembly.

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Los Alamitos, CA, United States of America

Abraham Person