System evaluation of offshore platforms with gas liquefaction processes

Highlights: • Energy and exergy performance of floating production storage and offloading platforms. • Integration of gas liquefaction processes. • System analysis of the hybrid processing plant. • Significant changes of the plant layout and efficiency. Floating, production, storage and offloading plants are facilities used for offshore processing of hydrocarbons in remote locations. At present, the produced gas is injected back into the reservoir instead of being exported. The implementation of refrigeration processes offshore for liquefying natural gas provides the opportunity to monetize offshore gas resources. The present work analyzes the performance of offshore platforms, from the oil processing to the gas liquefaction system. Different feed compositions, system layouts and liquefaction processes are considered. Potential system improvements are discussed based on an energy and exergy analysis. Compared to a standard platform where gas is directly injected into the reservoir, the total power consumption increases by up to 50%, and the exergy destruction within the processing plant doubles when a liquefaction system is installed. It is therefore essential to conduct a careful analysis of the trade-off between the capital costs and operating revenues for such options.