Preparing the Way for Future Offshore LNG Marine Terminals
Authors: Cox Phillip John 
Published: October 2008

Future offshore LNG Marine Terminals, whilst incorporating much of today's technology for liquefaction or regasification, will require new equipment and methods to ensure that safety and availability levels are both met. Whilst good availability levels for the terminal linked to up-time and thus to the number of LNG transfers per year will lead to a profitable operation; safety issues, especially when in harsh marine environments, will tend to diminish availability time. These two conflicting factors must however be addressed together and an equitable compromise reached.

A third element has to be included- that of new equipment and its certification.

The LNG Industry is presently studying new methods for the transfer of LNG in harsh marine conditions. Some significant changes are already taking place to prepare the ground for these new challenges. Recently the onboard regassification of LNG has been carried out on dedicated LNG carriers, whilst ship-to-ship transfer in calm conditions using flexible hoses has broken new ground.

The subject LNG transfer system has been developed, tested and qualified for harsh environments, and to be able to connect, transfer LNG and disconnect in marine conditions far in excess of those acceptable today. However overall terminal operability is needed to ensure that the equation between safety and availability gives the best result.

Full operational procedures, plus certification, maintenance and on-site handling must all be evolved and found to be acceptable by the marine terminal operators. This paper will address all of the above issues, and make a comparison between aerial and floating flexibles, and the different advantages of each system, based on meteo-oceano data for specific sites.

Finally in conclusion, relative costs will be discussed, especially with reference to the use of dedicated or non-dedicated LNG carriers, and the benefits that increased uptime can bring to the overall operability of an LNG chain. The integration of new, high technology equipment and methods at a reasonable cost will further push the limits in which Marine LNG terminals can function, but the investment will be rapidly amortized by the accrued safety and availability of such terminals.

Introduction

The development of new technology and methods has always been driven by Industry requirements. A typical example of this has been the ongoing push into deep water for new Oil & Gas reservoirs, and the evolution of flexible riser systems. In its turn, the LNG Industry is today in full expansion and the development of Marine LNG Terminals, either nearshore or fully offshore, at the liquefaction or the regasification ends of the chain, is becoming a reality.

The new technology required for dynamic LNG transfer systems incorporating a new generation of large bore, heavy duty cryogenic flexibles brings together a group of different parties, including equipment manufacturers and suppliers, regulatory bodies, marine operators and of course the Oil & Gas majors. New technology and methods must be fully tested and certified without any compromise on safety standards, and ease of operability linked to terminal availability is the key to success.