Shell Oil Comapny

Carl G Langner

Ronald Marshall Bass

Joe O Esparza

Ray R Ayers

Robert H Wittman

Frans F Kopp

William H Petersen

Paul B Ritter, Jr

Byron Lee Newberry

Apparatus and method for electrically heating a segment of a subsea pipeline are provided. The annulus between the pipes electrically isolates the pipes, but at the ends of the segment the concentric pipes are electrically connected. The inner pipe may be thermally insulated. Electrically insulating water stops are provided to act as flood control barriers in the event the outer pipe is breached. Collars on seals around the water stops may help avoid electrical shorts and packets of super-absorbent may be in place to further reduce the risk of electrical faults.

Annulus for electrically heated pipe-in-pipe subsea pipeline

A heated flowline electrical isolation joint is disclosed for introducing current into a pipe-in-pipe system having an outer and an inner pipe. A hub presents a load flange having tension and compression load shoulders on its terminal end and connects to the inner pipe on its other end. An end flange presents an end flange load shoulder on one end and a high strength, highly electrically insulative first ring separates the compression load shoulder from the end flange load shoulder which engage therethrough in a load bearing relationship. A plurality of o-ring seals secure the compression load shoulder-to-first ring-to-end flange load shoulder interfaces. A retainer flange connects to the end flange on one end and to the outer piper on the other end, encircling the hub and presenting a retainer flange load shoulder. A second high strength, highly electrically insulative ring separates the tension load shoulder of the hub from the retainer flange load shoulder which engage therethrough in a load bearing relationship. A plurality of o-ring seals securing the tension load shoulder-to-second ring-to-retainer flange load shoulder interfaces. An electrical feedthrough tubes receives an electrical penetrator which reaches through the retainer flange to electrical connection with the hub. An electrically insulative material in the annulus between the hub and the retainer flange and between the electrical penetrator and the electrical feedthrough tube secures electrical isolation across non-load bearing areas.

Joint for applying current across a pipe-in-pipe system

A method for enhancing the flow of heavy crude oil by heating a subsea pipeline is disclosed in which a pipe-in-pipe subsea pipeline is established having a flowline for transporting well fluids in the form of an electrically conductive inner pipe concentrically surrounded by an electrically conductive protective outer pipe and the inner pipe is electrically insulated from the outer pipe along the length of the subsea pipeline. The pipe-in-pipe subsea pipeline is electrically heated continuously along its length to maintain the temperature of crude oil at a level facilitating pipeline transportation, this heating comprising passing alternating electrical current along the exterior surface of the inner pipe and along the interior surface of the outer pipe. In this manner the crude oil can be maintained at a temperature at which viscosity does not prevent efficient and economical pipeline transport.

Method for enhancing the flow of heavy crudes through subsea pipelines

A method for installing an offshore pipeline is disclosed in which the inner and outer pipes are structurally connected at a terminal end of a pipe-in-pipe flowline and centralizers are placed in the annulus to provide lateral support and maintain concentricity between the two pipes and to prevent buckling of the inner pipe. The working end of the pipeline is suspended under construction in a substantially vertical position within slips at the weld floor of a J-lay installation barge and sections of inner and outer pipe are added. Inner pipe is added by sections by grasping and orienting the section of inner pipe to a vertical position and the section is brought into abutting position with the inner pipe at the working end of the pipeline under construction, welded in place, and the weld is coated with an arc resistant material. Sections of outer pipe are added by grasping and reorienting to a vertical orientation, sliding the section down over the section of inner pipe just welded in place, bringing the section of outer pipe into abutting position with the working end of the pipeline under construction and welding it into place. The working end of the pipeline is then advanced through the slips to bring the end of the section of outer pipe added adjacent the weld floor and the foregoing steps are repeated as necessary to add additional sections of inner and outer pipe to complete the pipeline.

Method for pipeline installation

A method is disclosed for pipeline leak detection in which a vacuum is maintained in the annulus of a pipe-in-pipe flowline with a vacuum pump having a discharge reservoir which is monitored for the appearance of water and hydrocarbon vapors. In another aspect of the invention pipeline leak detection is accomplished through maintaining a gas at a nominally constant pressure in an annulus of a pipe-in-pipe flowline and monitoring the annulus for pressure increase indicative of water or product intrusion into the annulus.

Method for pipeline leak detection

A system for direct electric heating of a subsea pipeline is disclosed in the form of a pipe-in-pipe flowline having an electrically conductive outer carrier pipe and an electrically conductive inner pipe or flowline arranged longitudinally, substantially concentrically within the outer pipe. An annulus is defined between the inner and outer pipes and a pipe insulating joint assembly structurally joins, but electrically insulates, the inner and outer pipes at a first end of the subsea pipeline. A power input provided on the surface facilities is electrically connected across the inner and outer pipes at the first end of the pipeline, and an electrical pathway completes the circuit by connecting the inner and outer pipes at the second end of the pipeline.

Direct electric pipeline heating

A helical bundle of tubes is fabricated with a carousel-type machine, preferably rotating about a vertical axis. Spools of coil tubing are mounted on radial beams extending from a central rotating hub, and are indexed to maintain the axes of the spools in a constant direction. In the preferred vertical rotating axis configuration, the tubes are pulled off the spools by an overhead capstan, and the finished bundle is deposited on a take-up reel. A preferred way of indexing the spools uses chains passing around equal size sprockets attached to the vertical support shafts with at least one of the chains passing around a stationary central sprocket.

Carousel assembly of helical tube bundles

A diverless and guidelineless method to connect two subsea flowlines by a jumper assembly is provided. Pivotable stabs and fluid connection means are provided on each end of the jumper assembly. The stabs mate into receptacles located on the subsea flowline connections. The flowline is preferably lowered vertically and hinged over while sequentially landing the two pivotable stabs into their respective stab receptacles.

Subsea wellhead connections

A method and apparatus is described for installing an export production riser on an offshore production platform that moves in response to ocean waves, wind and currents. The riser is provided with a catenary shape between the near vertical connection on the platform and the horizontal position on the seafloor. The upper end of the riser is maintained at a nominal inclination from the vertical to control excessive bending stresses in the riser. A flexible joint is provided at the upper end of the riser to allow rotational movement between the riser and platform as the platform moves.

Elastomeric swivel support assembly for catenary riser

A pipeline breakaway mechanism is provided which includes an elbow in a pipeline and two clamps holding the pipeline to a structure such as a platform or another pipeline. When a strong pull is exerted on the pipeline, the pipeline is bent until it buckles around the first clamp; the first clamp then fails at a preset load, causing the pipe to bend around the second clamp and causing the previously formed buckle to straighten. This buckling and straightening of pipe causes the pipe wall to fracture at a load much smaller than its tensile strength.

Pipeline breakaway protection mechanism

The present invention pertains to a pipeline having a deliberate weak link to relieve a large tension load, said weak link being a pipe loop in said pipeline of sufficient weakness to fail prior to reaching said large tension load.

Pipe loop expansion/breakaway protection device

A heave compensating support system is disclosed for positioning a subsea work package. The present invention provides a subsurface buoy with a lift line connected to the subsea work package and a compensating lift line having a catenary loop below its connection to the subsurface buoy on one end and connected to a surface vessel on the other end, whereby the heave compensating support system elements cooperate to establish a natural frequency for the suspended subsea work package which materially differs from the average wave frequency acting upon the surface vessel.

Heave compensated support system for positioning subsea work packages

Riser clamps are installed onto fixed or compliant offshore platforms by a diverless technique. Each riser clamp is rigidly or hingedly attached to a heavy tapered wedge. Mating tapered receptacles are built into the platform, preferably at various levels along a corner leg. Only one lift line is utilized which may be either a drill string or wire rope, and one remotely operated vehicle (ROV) for observation, to lower and stab each riser clamp into one of the tapered receptacles on the platform.

Diverless installation of riser clamps onto fixed or compliant offshore

A flowline bundle is twisted or braided into a permanent rope-like helical configuration, prior to laying the flowline bundle offshore by the reel method. Apparatus for forming the helical flowline bundle includes a pipe twist head and a series of pipe tumblers alternating with intermediate pipe supports, which apparatus rotates and translates part of a flowline bundle while simply translating the other part.

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Spring, TX, United States of America

Carl G Langner