Abstract: A polygon shaped floating offshore structure for use in oil or gas drilling or production operations, having apertures in its sides in order to reduce the movement of the structure as a result of undersea currents. The structure contains a production platform extending above the ocean's surface, a series of buoyancy tanks providing the structure with the ability to float, apertures, surrounded by coamings, located on each side of the structure such that ocean currents are allowed to flow laterally through the center of the structure and such that oil and gas can dissipate from the center of the structure if a rupture occurs, a fluid retention tank and ballast in order to lower the center of gravity of the structure and make it more stable, and a centerwell running through the longitudinal center of the structure which allows one or more risers to run from the ocean floor to the operating platform. The structure can then be moored to the sea floor through the use of a catenary mooring system.

Abstract: A riser and tendon management system for offshore hydrocarbon production facilities has a data acquisition system with instrumentation suitable for gathering all necessary information concerning the immediate condition of the facility and a riser and tendon analysis system for comparing actual with ideal conditions for the facility. Information is generated as to what corrective action must be taken. The analysis system stores past corrective actions and results and factors this information into the current suggestion for correction thereby reducing riser and tendon stress while increasing their fatigue life.

Abstract: A floating drilling platform having dual work stations is disclosed for performing deep sea drilling and/or hydrocarbon production operations. The structure of the platform is designed to accommodate replaceable modules which facilitate the installation and removal of either a drilling derrick or production equipment. Thus, during the drilling phase of a reservoir's development, the platform may be outfitted with dual drilling derricks while at later times the platform may be outfitted with a drilling derrick and a full production facility. Various expedients are available to permit the equipment of one work station to be used in conjunction with the equipment of one other. Simultaneous management of dual conductors is enabled by a dual riser management system which models in real time riser behavior under varying environmental and other operational conditions. The dual riser management system includes a riser analysis subsystem, a mooring analysis subsystem and a vessel stability analysis subsystem.