Conoco Inc.

Imodco, Inc.

Andrew F Hunter

James D Bozeman

Charles N White

Norman W Hein, Jr

Douglas H Warren

Glenn M Wald

Steven M Craig

Robert R Masecar

Jeffrey L Mueller

Wen J Wang

Lee M Sandora

Robert A Zimmer

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.

Offshore pipeline system

The interruptive mobile production (IMP) system comprises a floating semisubmersible structure with equipment and facilities for hydrocarbon production in association with a small tension leg wellhead platform (TLWP) having direct vertical access. The small TLWP has an upper deck positioned above the surface of the water with wellhead equipment thereon and has risers generally vertically connecting subsea wells to the upper deck. Lateral bending restraints of the risers and tendons are preferably located at about the same horizontal level as the lower pontoon section. The semisubmersible structure can be conveniently disconnected from its moorings and from the wellhead platform for demobilizing to another location while the TLWP remains tethered in place.

Interruptive mobile production system

Apparatus for mooring attachment of a floating tension leg platform to a subsea anchorage. The apparatus includes a tendon with an enlarged connector on one end, the connector being formed by a frustoconical bearing surface extending away from the end to which it is connected. A connector shroud partially surrounds the frustoconical surface and is connected to it by an elastomeric bearing. An inwardly sloping surface engages a supplementarily sloped surface formed on the attachment receptacle load ring to increase hoop strength. A side-entry bottom receptacle is also disclosed.

Mooring apparatus and method of installation for deep water tension leg

An apparatus and method are provided for dewatering an interior of a hollow tension leg connecting a tension leg platform to a floor of a body of water. The apparatus includes a pump having a suction inlet defined on its lower end and a discharge outlet on its upper end. An elongated storage tank is attached to the upper end of the pump above the pump and has a tank interior communicated with the discharge outlet. The assembly is lowered on an electric wireline through which power is conducted to the pump. The pump fills the tank and then the assembly is withdrawn from the tension leg and the water is drained therefrom. The assembly can be repeatedly lowered into the tension leg and withdrawn therefrom until the tension leg is substantially completely dewatered. Solid debris can be removed from the tension leg prior to dewatering.

Tension leg dewatering apparatus and method

A method for securely mooring a floating tension leg platform and an anchoring base template. The method involves swinging an end of a neutrally buoyant, one piece tendon which has an enlarged connector downwardly into position adjacent an anchoring receptacle, pulling the enlarged connector through a side-entry opening in the receptacle, lifting the tendon to seat the enlarged connector in a load ring of the receptacle, adjusting the effective length of the tendon to place it in tension and repeating these steps for each of the mooring tendons. A one-piece, thin-walled, neutrally buoyant tendon is also disclosed.

Apparatus for attaching a floating tension leg platform to an anchoring base template on the subsea floor. The apparatus includes an external mooring porch for each tendon, the porches being mounted on the outside surfaces of the platform's columns.

A method of placing a template on the seafloor beneath a floating vessel. The method comprises suspending the template beneath at least one sling-mounted pendant buoy and using a tow cable and restraint cable to position the template in a position generally centered beneath the vessel. An extendable support, such as a drill string, may be connected to a previously attached descent sling, control lines and buoy slings detached, additional ballast added as needed, and the template lowered to the seafloor.

Method of installing a template on the seafloor

A light-weight, modular drilling template. A template is constructed of light-weight tubular steel having ring stiffeners to provide adequate crush resistance to withstand collapse under hydraulic loading provided by water pressure at 1800 feet water depth. The template is constructed as a pod-receiving frame with separable pods that may be installed after the frame has been set on the seafloor and leveled. The individual pods may be fine tune leveled by means of adjustable jacking mechanisms that form part of the latching devices that secure the pods to the frame. A method for installing a foundation template subsequent to installing the drilling template is also described.

Modular drilling template for drilling subsea wells

A method for securely mooring a floating tension leg platform to an anchoring base template. The method involves swinging an end of a neutrally bouyant, one piece tendon which has an enlarged connector downwardly into position adjacent an anchoring receptacle, pulling the enlarged connector through a side-entry opening in the receptacle, lifting the tendon to seat the enlarged connector in a load ring of the receptacle, adjusting the effective length of the tendon to place it in tension and repeating these steps for each of the mooring tendons.

In a Tension Leg Platform, the common practice is to locate the well and anchor templates on the sea floor. This practice results in unequal lengths for the mooring elements which extend to the base of the floating structure and the well risers which extend to a well deck level which is elevated above the base of the floating structure. As a consequence, complicated tensioning systems having an extremely long stroke may be required for the well risers. The present invention provides for a well template which is elevated above the anchor templates at a level which equalizes the lengths of the mooring elements and the well risers. The well and anchor templates are constructed in a unitary structure to facilitate installation and assure proper spacing of the templates with respect to each other. In preferred embodiments of the invention, subsea storage is provided as well as curved conductors which facilitate angular deviation of the wellbores away from the template and J-tubes for the pull-in of subsea flowlines.

Unitized TLP anchor template with elevated well template

Personnel evacuation apparatus for use with an offshore platform. A launching ramp that is mounted to the platform by a gimbal is stowed in a vertical position with a survival vessel secured in the entry end of the ramp. A release mechanism activatable from the deck of the platform enables flotation members secured to the exit end of the ramp, to pivot the ramp about the gimbal to its deployed position. The gimbal further permits the ramp to maintain a usable orientation in spite of inclination of the deck of the platform by 25.degree. due to pitch, roll or yaw. The exit end will pivot under wave action so as to gravity launch the survival vessel downwind and, upon release of the boat securement, carry the vessel safely away from the platform.

Personnel evacuation apparatus for an offshore platform

The present invention provides methods and apparatus for tension compensation in the tension legs used to moor a floating platform to the sea floor. The apparatus includes one or more hydraulic jacks, each having a cylinder coupled through a load block to a tension leg, and having a piston cooperating with a load block plug coupled to the floating platform. An accumulator supplies hydraulic fluid to the jacks to compensatingly adjust the relative position of the piston and cylinder to selectively maintain the tension loading of the tension leg.

Tension control system for controlling the tension in platform

A connector apparatus for connecting a tension leg platform mooring tether to a subsea foundation, the apparatus comprising: a plug positioned on the lower end of the mooring tether for mating union with a receptacle positioned in the foundation so that the plug is readily positioned in the receptacle to maintain the mooring tether in connection with the foundation with the plug being readily removable from the receptacle when desired.

Tension leg platform mooring tether connector

A transfer and docking apparatus for use on variable draft marine vessels. A plurality of parallel sloping fenders extend from above the maximum draft level of the vessel to below the minimum draft level of the vessel. A stairway is provided adjacent and parallel to at least one of the fenders and is mounted inboard of the fender.

Growing community of inventors

Houston, TX, United States of America

Andrew F Hunter