This paper describes the development of a technical solution for the two offshore platforms of the Sakhalin II project, in order to cope with the special characteristics of the arctic and seismic environments. The emphasis is on describing the design challenges and how they were addressed during the Front-End-Engineering-Definition leading to the concepts currently going through detailed design. Transportation and installation aspects, in such a remote environment with a limited weather window, form an integral part of concept development and needed to be addressed early on.
The structural solutions for the two offshore platforms comprise a four-legged concrete gravity based structure (GBS), supporting an integrated deck that includes a seismic isolation system between topsides and GBS. In addition to providing seismic isolation, this system also effectively isolates the topsides from wave, sea ice and thermal contraction loadings and hence simplifies the design considerably.
The structural concepts, which at the time of writing are at the final stages of detailed design, provide effective solutions taking due consideration of constructability, transportation, installation and operation for 30 years.
Christopher S. J. Clarke, AMEC Oil and Gas
Robert Buchanan, AMEC Oil and Gas
Michael Efthymiou, Sakhalin Energy Investment Company Ltd
Christopher Shaw, AMEC Oil and Gas