Shell Oil Comapny

Paul R Johnson

David A Huete

Peter W Marshall

A parasite mooring system is disclosed for restraining a compliant platform with respect to an auxiliary vessel. The parasite mooring system includes a parasite mooring line, a platform termination securing the parasite mooring line to the compliant platform; and a grip securing the parasite mooring line to a mooring line of the auxiliary vessel passing beyond the compliant platform. Another aspect of the present invention is a method for conducting offshore well operations in which a semisubmersible vessel is brought adjacent a compliant platform such that at least one mooring line of the semisubmersible vessel extends past the compliant platform and a parasite mooring line from the compliant platform is connected to the mooring line of the semisubmersible vessel. The parasite mooring line can then be tensioned to displace and restrain the compliant platform out of its normal position substantially over a well pattern and position the semisubmersible vessel over a selected well site within the well pattern at a location at the surface of the water which is not accessible to the semisubmersible vessel with the compliant platform in its normal position.

Complaint platform with parasite mooring through auxiliary vessel

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.

Buoyant tower flexure joint

Motion compensated load-lifting apparatus for use on marine vessels. Apparatus includes a traveling weight used to maintain tension in the load-lifting member, and a locking mechanism to prevent movement of the traveling weight in one direction. The locking mechanism, such as a ratchet and pawl, can be employed to lift the load from the vessel at optimum periods of wave movement. Load direction sensing devices prevent attempted lift of the load as the vessel falls.

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Houston, TX, United States of America

Paul R Johnson