Quantitative Risk Analysis of Oil and Gas Fires and Explosions for FPSO Systems in China

Abstract

The LH11-1 FPSO is an 80,000 t cylindrical structure that is responsible for the processing, storage, and offloading of process oil from existing and newly developed oilfields. In this paper, a full probabilistic analysis was developed based on very detailed CFD simulation results to evaluate ventilation, gas dispersion, explosion, and fire scenarios. A detailed fire and explosion risk analysis of LH11-1 FPSO was performed based on NORSOK Z-013 and FABIG Technical Note 11. The risk-based calculations were performed applying FLACS, KFX, and DNV GLEXPRESS Fire. Finally, the oil and gas dispersion, fire, and explosion consequence risks were calculated under the credible combination of leak frequency and leak location. By this probabilistic risk analysis, it was found that the west wind could generate optimal ventilation conditions for the topside process area of FPSO compared to other wind directions, while the hull region was poorly ventilated for all wind directions. The explosion risk analysis showed that the FPSO system would take no action in terms of explosion risk according to the acceptance criteria of 10−4 occ/year. Meanwhile, the fire risk analysis demonstrated that the PR1 first and second deck, PR2 first and second deck, process deck, offloading on starboard, and the base of the flare tower would have different impacts from the fire, and the PR1 first deck and PR2 first deck at the topside deck would be severely impacted regions.