Risk Identification And Quantitative Assessment For Escape,Evacuation,Rescue On Offshore Drilling Platforms

When accidents occur on the offshore platforms,the reliable Escape,Evacuation,and Rescue(EER)can avert or reduce the catastrophic consequences.As the main structures of production and life on the sea,the offshore platforms,which have harsh working environment,narrow working space,concentrating operating equipments,are prone to accidents with a high probability.With the pace of deep-water oil and gas exploration and development keeping ahead,higher effective EER mechanism of offshore platforms is required.Taking the EER operations on offshore platforms as study subject,the relevant research about the performance and success of EER system,and the evacuation simulation and emergency rescue efficiency are studied in this paper.Based on fuzzy random Petri Network and Markov method,a performance analysis model of EER operations on offshore platfroms is established.The EER response model of the offshore platforms that start out with accidents occured is established according to the three processes of escape,evacuation and rescue.The Stochastic Petri Net(SPN)model of EER operations is constructed based on the EER response model,and the rationality of the SPN model structure is verified from three aspects of accessibility,activity and boundedness.The steady-state probability equation of SPN is established by integrating fuzzy number and SPN with markov theory to identify the key EER operation steps from the static and dynamic aspects.The results emphasize the importance of timely EER instructions,and the necessity for regular emergency EER drills and rescue forces to cooperate with each other.A quantitative analysis model is proposed by integrating Bayesian network(BN)with fuzzy AHP to estimate probability of success of EER in offshore platform accidents.Factors affecting the EER success are identified from aspect of equipment,surrounding,personnel and organization,then the BN of EER are established respectively.The fuzzy AHP and decomposition method is applied to elicit conditional probability table(CPT)of BN.The BN with CPT can calculate probability of success of EER practically.Moreover,based on backward inference,the probability updating is implemented when a new evidence is introduced.A sensitivity analysis based on mutual information method is conducted to identify the most critical risk factors.Case study shows that the model is capable of seeking out critical risk factors and carrying out quantitative analysis of accidents.On the basis of engineering data,the numerical model of offshore platform escape process under explosion scene is built with the judgment criteria of explosion risk and evacuation risk.Based on the FLACS simulation results,the explosion hazardous zone is identified from overpressure index and temperature index.After determining the hazardous area,two scenarios,namely scenario 1 and scenario 2,with different evacuation routes are carried out based on Buildingexodus software.The evacuation time,waiting time index,optimal performance statistic,mean non-flow statistic are estimated to evaluate the evacuation efficiency of these two evacuation scenarios.The results show that improper distribution of population for each exit and the congestion and queue occurred at the main exits are the two main reasons for the low evacuation efficiency.Combined with the characteristics of emergency rescue and rescue process of marine emergencies,the system dynamic model of emergency rescue system for offshore platforms is established.Referring to the process and characteristics of maritime emergency rescue,casual loop diagram of the factors affecting the emergency rescue system of the offshore platform is constructed,and then the system dynamic model of emergency rescue system for offshore platforms is established from two aspects of accident information flow and emergency relief material dispatch.Finally,the influence of different factors on the efficiency of emergency rescue is discussed by using the methods of system dynamic.The results show that enhancing the cooperation level of accident information disposal in various rescue departments,reducing unnecessary intermediate links and improving the modernization level of emergency rescue supplies reserve base are important means to improve the efficiency of emergency rescue.