Technology Focus: Offshore Facilities (February 2009)

Abstract

Technology Focus After many years of development work, as well as many unsuccessful attempts, the first liquefied-natural-gas (LNG) floating production, storage, and offloading (FPSO) initiative was launched in 1976 by Linde, Technigaz, et al. under the name Consortium 76—offshore LNG now is a reality. The first LNG receiving terminal installed on a gravity-based structure offshore Rovigo, Italy, will be commissioned soon. The first floating storage and regasification unit (FSRU) permanently moored in open sea offshore Livorno, Italy, is under construction, and several LNG carriers equipped with regasification facilities are able to deliver gas at several offshore ports in North America. Offshore liquefaction also seems close to materialization, with several participants (including oil companies; engineering, procurement, and construction contractors; ship owners; and others) developing LNG FPSO solutions for stand-alone gas fields or for associated-gas developments. Two main ways to approach these facilities seem to be pursued by the various participants. The "big way" is followed mainly by major oil companies: It aims at developing large-capacity liquefaction units (3×106 tonnes/a and larger) by use of processes generally derived from latest-generation onshore liquefaction cycles. A second trend, which could be called the "small way," targets smaller capacities, by use of less-efficient processes often based on nitrogen cycles, but having better suitability for use on board a floater. While the latter probably has a wider range of potential application cases and would ease topside layout and safety concerns for a lower overall capital expenditure, the former will provide higher liquefaction efficiency and will target economies of scale. In turn, it might be applicable to only a limited number of relatively large gasfield developments. Today, both approaches have equal chances to open the way for offshore floating liquefaction, but, certainly, both will need to rely on experienced companies that can gather and leverage experience in offshore regasification gained from the first FSRUs, combined with experience in large oil FPSOs and in onshore liquefaction. All the industry needs now is a good gas field! Offshore Facilities additional reading available at OnePetro: www.onepetro.org OTC 19429 • "A Coupled FE-SPH Approach for Simulation of Structural Response to Extreme Wave and Green Water Loading" by J.C. Campbell, Cranfield University, et al. OTC 19239 • "Innovative Pipe System for Offshore LNG Transfer" by Ing. C. Frohne, Nexans Deutschland Industries, et al. OTC 19315 • "Deepwater Moorings With High-Stiffness Polyester and PEN-Fiber Ropes" by P. Davies, IFREMER Brest, et al.