Study On Risk Assessment And Optimization Of Emergency Scheme For Blowout Out Of Control In Deepwater Drilling

The operation environment of deepwater drilling is complex,and the operation risk increases accordingly.Uncontrolled blowout is considered to be the worst accident in deepwater drilling.At present,the research on blowout out of control in deep water drilling mainly focuses on the mechanism of the accident and the measures to reduce the probability of blowout,and there is no research on the emergency disposal after blowout out of control.It is of great significance for deepwater drilling safety and emergency rescue to carry out risk assessment and emergency disposal scheme optimization of deepwater drilling blowout out of control,which can improve the accuracy of accident response and reduce the emergency response time after the accident.In this paper,the Deepwater blowout accident is taken as the research object,combined with Deepwater Horizon accident and offshore 981 operation conditions,according to the basic method of scenario construction,seven deepwater blowout out of control scenarios are constructed,and 12 secondary scenario units are obtained by discrete reorganization of the seven scenarios.According to the emergency measures taken by different second level scenario units,21 first level operation units and 32 second level operation units are established in the process of emergency disposal,which are used as the basis for the follow-up study of this paper.Based on the full investigation of BP Deepwater Horizon accident and the analysis of accident causes and weak links of the system,the risk evaluation index system of deepwater drilling blowout out of control is established with 12 secondary scenario units established in this paper as the core,and the risk evaluation model of deepwater drilling blowout out of control is constructed by using cloud model.Based on the four dimensions of economic index,safety index,technical index and timeliness index,an index system for optimizing the emergency disposal scheme of deepwater drilling blowout out of control is established,which includes eight evaluation elements.Deep water drilling blowout out of control accident is a typical poor information system.By using the advantages of grey correlation analysis in dealing with poor information system and TOPSIS method in scheme optimization,the concept of composite closeness degree is introduced,and the reverse order problem of TOPSIS method in scheme sequencing is improved,and the optimization model of blowout out of control emergency disposal scheme based on Euclid gray TOPSIS is established.In the weight calculation of risk evaluation index and scheme optimization index,AHP and entropy weight method are used to calculate the subjective weight and objective weight respectively,and Lagrange conditional extremum principle is used to combine the subjective and objective weight.Finally,scenario 5is taken as an example to apply the risk assessment model and emergency disposal scheme optimization model of deepwater drilling blowout.The research results show that the risk assessment model of blowout out of control in deepwater drilling can accurately calculate the risk level of blowout out of control,which is convenient to start the emergency plan of corresponding risk level;the optimization model of blowout out of control emergency disposal scheme based on Euclid gray TOPSIS established in this paper,which comprehensively considers the proximity of spatial distance and the similarity of geometric shape Compared with the results of grey correlation method or TOPSIS method alone,the difference between the closeness degree of each scheme is larger.The advantage is that if a new operation scheme is added to the alternative scheme,the discrimination of the evaluation results will be more obvious,eliminating the same and the other problems existing in the calculation results using a single method.