Offshore Natural Gas Liquefaction Process Selection and Development Issues

摘要

Liquefying natural gas on an offshore facility servicing an underlying gas field has yet to be sanctioned anywhere in the world, in spite of several feasibility studies demonstrating its potential viability. The perceived risks associated with deploying unproven technology in a high construction cost and volatrile gas price environment have so far inhibited offshore liquefaction projects. Such technology however has the potential to unlock substantial volumes of remote and otherwise stranded natural gas for commercial exploitation. With strict no flaring aspirations in many countries discovering associated gas can pose obstacles to developing an oil field if no gas utilization strategy is commercially viable. Key issues for offshore gass liquefaction processes are: compactness (low weight –small footprint), ease of operation, process safety, and efficiency. Particular attention is paid to the lower-efficiency turboexpander processes for plant capacities up to 3 million tons per annum (MTPA, about 0.43 Bcf/d). These cycles offer several advantages over the alternative optimized cascade and mixed refrigerant (MR) liquefiers..