Development of Floating LNG Production Units with Modular/Scalable SMR Processes

Abstract

Abstract The world wide market for LNG continues to grow rapidly. Traditionally, base load LNG plants have provided the majority of this LNG supply. As the industry has grown, base load plants have grown increasing larger and more difficult to site. Additionally, the number of fields with sufficient reserves is diminishing. Owners are now turning to developing mid-scale projects with Floating LNG production systems. A variety of configurations have been put forth and a few are progressing. The single mixed refrigerant process offers an excellent approach to developing the topsides process units required for LNG production. With real estate on floating structures at a premium, compact, modular facilities are a must. The SMR process is readily modular and scalable to fit the production profile of these projects. Modular concepts from 0.5 MMTPA to 6.0 MMTPA have been developed to fit both tanker retrofits and new build ships. Also, the process offers significant reduction in equipment and power versus expander based processes. This paper will cover the technology as applied to floating structures with emphasis on efficiency and footprint for a variety of feed gas applications. Offshore Process Requirements LNG production facilities to date have all been onshore locations. While many of the same processes are used for both onshore and offshore locations, the requirements for offshore developments are unique to this environment. Some of the key criteria include:Minimizing footprint- Offshore real estate is the critical item in project cost. The minimization of the footprint of the process plant is essential to developing an economically attractive project.Minimize equipment items- The key objective for the process units to achieve an optimal footprint is to minimize the number and complexity of the equipment needed. Single mixed refrigerants produce the lowest equipment count of all processes.Minimize weight and single module lift weights - The cost of structures to support the equipment and modules is a key cost item. Also the lift weight of the individual modules is critical.Minimize module interconnections- The simplification of processes to minimize interconnections reduces the cost and complexity of the installation. Multiple loop refrigeration systems suffer from extreme numbers of interconnections between the loops.Accessibility- The offshore process systems must be accessible for maintenance and egressFlexibility to handle multiple feed gas cases- Onshore developers have learned (some the hard way) the liquefaction processes need to be able to handle a range of feed gases. Single mixed refrigerants excel in this area due to ease of changing the system during operation.