Concept Selection Philosophy for Floating Control Facilities

Abstract

Floating control facilities (FCFs) are designed to support fields using only subsea production system. Potential concepts, including Tension Leg Platform (TLP), Spar and semi-submersible can be selected as the FCFs. This paper discusses the philosophy of concept selection for FCFs. Two basic considerations for concept selection for FCFs are functional requirements and costs. Different structure types are first to be sized to meet the functional requirements for given water depths, environmental conditions and soil conditions. Then the costs for the procurement, construction, installation, hook up and commissioning for different concepts are estimated based on the sizes. Finally, the most cost-effective concept is chosen for further study to confirm the feasibilities of the concept by detailed analyses. Global sizing tools assisting concept selection have been developed by Ocean Dynamics LLC (Limited Liability Company) (ODL) over the past years. For a given concept, these sizing tools can find the optimized size based on costs to meet the functional requirements. Capabilities of the sizing tools cover the general layout, weight estimate (hull and deck), riser weight and stiffness estimate, loading conditions (transportation, normal operating, extreme, survival), hydrostatics and stability, natural periods, motions, air gap, environmental loads (wind, current, and mean wave forces), mooring sizing, cost estimate, and optimization based on the total costs. Two case studies in two different water depths, 140m and 1200m, are presented to illustrate the procedures and considerations in concept selection for floating control facilities. The FCFs used in the case studies are to support a Super Puma helideck, satellite communication equipment, an umbilical riser and option for a 3.5″ pipeline riser, with a total estimated topside payload as 400 Metric Ton (MT).