Abstract: A system for supporting multiple-well-site, offshore, hydrocarbon-bearing fields, each well-site has one or more wells. In general, the system first comprises a floating vessel that is relocatable from a first subsea well-site to a second subsea well-site. The system also comprises two separate systems: (1) an operations control system for providing subsea well-site operations such as power and communications; and (2) an intervention system for conducting intervention services to an individual subsea well such as workover services and maintenance services. The operations system may provide control to wells and other subsea equipment at either the first well-site or the second well-site, regardless of the location of the floating vessel. The intervention system may provide workover and/or maintenance to subsea equipment or individual wells at the well-site at which it is located.

Abstract: A system for supporting multiple-well-site, offshore, hydrocarbon-bearing fields, each well-site has one or more wells. In general, the system first comprises a floating vessel that is relocatable from a first subsea well-site to a second subsea well-site. The system also comprises two separate systems: (1) an operations control system for providing subsea well-site operations such as power and communications; and (2) an intervention system for conducting intervention services to an individual subsea well such as workover services and maintenance services. The operations system may provide control to wells and other subsea equipment at either the first well-site or the second well-site, regardless of the location of the floating vessel. The intervention system may provide workover and/or maintenance to subsea equipment or individual wells at the well-site at which it is located.

Abstract: An earthquake-compliant offshore platform for use in regions of strong earthquakes is disclosed in which the natural vibrational period of the jacket structure is preferably in the range of about 4 seconds to about 8 seconds, which is between the primary excitation period of earthquake energy and the primary storm wave period. The earthquake-compliant jacket structure is lighter than a conventional steel battered jacket for the same location and conditions and has a constant cross-section. The vibrational period of the earthquake compliant platform can be tuned by altering structural stiffness or mass.

Abstract: A well system, and a method for installing the well system, for use in producing hydrocarbons from a subterranean reservoir located beneath a body of water is disclosed. The well system is intended for use in conjunction with a bottom-founded offshore platform. The inventive well system eliminates the conductors traditionally used in offshore platform well systems. According to the invention, a subsea guide template and an outer casing string extending downwardly from the guide template to a first predetermined depth less than the depth of the reservoir are installed prior to installation of the offshore platform. Thereafter, the platform and the first intermediate casing string are installed, in either order. Drilling for the first intermediate casing string takes place in the open hole defined by the outer casing string with all returns of drilling fluid and drill cuttings occurring at the seafloor.

Abstract: An independent modular structure for providing lateral support for the well conductors of an offshore well platform and a method for designing and using such structure are disclosed. The modular structure can be inserted into a void in the jacket of the well platform. The vertical spacing between adjacent support points on the modular structure is determined by the lateral support requirements of the well conductors. Accordingly, the design of the platform jacket may be optimized without consideration of the lateral support requirements of the well conductors.

Abstract: A complaint offshore platform in which the primary restoring force to lateral displacement is established by flex piles driven into the seafloor and fixedly secured to the platform legs a preselected distance above the seafloor. The platform includes a substantially rigid space-frame structure extending from the ocean bottom to a position above the ocean surface. A drilling and production deck is secured atop the space-frame structure. Shear piles extend through the base of the space-frame structure to prevent lateral displacement of the base while permitting the space-frame structure to pivot about its base. As the platform sways about its base in response to environmental forces, the flex piles establish a vertical couple at the location at which they are attached to the space frame structure. This couple resists movement of the platform away from a vertical orientation. In the preferred embodiment, the flex piles are secured to the platform at or near one-half the total height of the space-frame structure.