Floating LNG (FLNG) technologies are being deployed to monetize mid-sized offshore gas reservoirs, avoiding constructing a sub-sea gas pipeline to a land based LNG facility and export jetty. A previous OTC-Brasil paper (OTC-26158 Gas Pretreatment Considerations for Floating LNG) has discussed the pre-treatment options available for FLNG and this paper is a continuation discussing the liquefaction and mechanical drive options. The discussion will be broken down to offshore safety and economic considerations, the liquefaction technologies available and the mechanical drive technologies available.
Offshore liquefaction technologies are often novel and many lack offshore references. The available offshore liquefaction technologies and Licensors will be presented. Because of the diversity of liquefaction technologies, the technologies will be grouped by process configuration, and then these groupings of technologies will be compared with an emphasis on safety, economics, scale and weight. Application of mechanical drives for centrifugal compressors in an offshore environment is well-practiced. Given this maturity, types of technologies will be compared on power ratings, availability, flexibility and weight, without reference to individual suppliers.
The reader will come away with an understanding of the trade-offs involved in technology selection of liquefaction and mechanical drives.