FLNG compared to LNG carriers - Requirements and recommendations for LNG production facilities and re-gas units

Abstract: An increasing price and demand for natural gas has made it possible to explore remote gasfields. Traditional offshore production platforms for natural gas have been exporting thepartially processed natural gas to shore, where it is further processed to permit consumptionby end-users. Such an approach is possible where the gas field is located within a reasonabledistance from shore or from an existing gas pipeline network. However, much of the world’sgas reserves are found in remote offshore fields where transport via a pipeline is not feasibleor is uneconomic to install and therefore, to date, has not been possible to explore. Thedevelopment of floating production platforms and, on the receiving end, regasificationplatforms, have increased the possibilities to explore these fields and transport the liquefiedgas in a more efficient form, i.e. liquefied natural gas (LNG), to the end user who in turn canreadily import the gas.Floating production platforms and regasification platforms, collectively referred to as FLNG,imply a blend of technology from land-based LNG industry, offshore oil and gas industry andmarine transport technology. Regulations and rules based on experience from theseapplications could become too conservative or not conservative enough when applied to aFLNG unit. Alignment with rules for conventional LNG carriers would be an advantage sincethis would increase the transparency and possibility for standardization in the building offloating LNG production vessels.The objective of this study is to identify the risks relevant to FLNG. The risks are comparedto conventional LNG carriers and whether or not regulatory alignment possibilities exist. Toidentify the risks, a risk analysis was performed based on the principles of formal safetyassessment methodology. To propose regulatory alignment possibilities, the risks found werealso evaluated against the existing rules and regulations of Det Norske Veritas.The conclusion of the study is that the largest risk-contributing factor on an FLNG is thepresence of processing, liquefaction or regasification equipment and for an LNG carrier it iscollision, grounding and contact accidents. Experience from oil FPSOs could be used in thedesign of LNG FPSOs, and attention needs to be drawn to the additional requirements due toprocessing and storage of cryogenic liquid on board. FSRUs may follow either an approachfor offshore rules or, if intended to follow a regular docking scheme, follow an approach forship rules with additional issues addressed in classification notes.