Shell Oil Comapny

Peter W Marshall

Paul R Johnson

An improved support system is disclosed for providing flexibility to a restrained termination of a highly pressurized, highly tensioned tubular element which extends from a subsea facility to a compliant structure. The tubular element is provided with an intermediate tension relief connection which separates a running span from a backspan and operably connects the tubular element to a support structure, transfering thereto a significant portion of the tension carried by the tubular element. This connection passes angular rotation of the tubular element but resists lateral motion, in effect forming a node in the deflection of the tubular element. A backspan is thus created in the tubular element having a tension load which is reduced from that in the running span, thereby increasing the flexibility apparent at the end of the running span, while maintaining a relatively restrained termination of the tubular element at the distal end of the backspan. Another aspect of the present invention is a method for increasing the flexibility at a termination of a highly tensioned, pressurized tubular element connecting a subsea facility to a compliant structure.

Backspan stress joint

The apparatus of the present invention comprises a compliant structure for use in reducing bending stress at the ends of an elongated cylindrical tether which may, for example, be used to connect a floating platform supported by a body of water to the floor thereof. The apparatus comprises a plurality of tubular support members concentrically arranged about the elongated cylindrical tether at the tether's end connection. Each tubular support member is connected to each adjacent tubular support member in a manner that allows the entire assembly of tubular members to deflect in unison as the cylindrical tether deflects.

Stress reduction connection apparatus for cylindrical tethers

A flexure joint is formed at the base of a buoyant tower structure by piles driven into the ocean floor. The geometric arrangement of these piles increases the buoyant tower's resistance to lateral forces at the base, while allowing rotational displacement about any horizontal axis, and also allows wells to be directed through the piles to formations located a substantial distance from the tower.

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Houston, TX, United States of America

Peter W Marshall