深水钻井隔水管紧急解脱失效动态风险分析

Dynamic risk analysis on emergency disconnection failure of deepwater drilling riser

为了分析钻井隔水管紧急解脱失效动态风险,保证深水钻井隔水管紧急解脱安全运行,通过辨识隔水管紧急解脱相关风险因素,以及隔水管紧急解脱失效的潜在后果,采用模糊事故树和事件序列图相结合的方法,建立隔水管紧急解脱失效后果模型;基于映射准则,将模型转换成贝叶斯网络,进行深水钻井隔水管紧急解脱风险的定量分析;研究了紧急解脱动态失效概率和关键致因,并从钻井隔水管系统设计、钻井作业、紧急解脱测试和操作等方面提出预防措施,以降低紧急解脱失效概率;以南海8号钻井平台为研究对象进行案例分析。研究结果表明:1年内隔水管紧急解脱失效的概率区间为0. 075 7至0. 105 0;台风、不合理的解脱时刻、过提力不足、井口倾角大和内波是导致紧急解脱失效的主要原因;该模型评估结果与实际情况相符合,该方法可用于钻井隔水管紧急解脱失效风险评价。

To analyze the dynamic risk of the emergency disconnection failure of drilling riser,and ensure the safe operation of the emergency disconnection of deepwater drilling riser,through identifying the relevant risk factors of riser’s emergency disconnection and the potential consequence of riser’s emergency disconnection failure,a model on the consequence of riser’s emergency disconnection failure was established by using the combined method of fuzzy fault tree(FFT)and event sequence diagram(ESD).The quantitative risk analysis on the emergency disconnection of deepwater drilling riser was carried out by converting the model into the Bayesian network based on the mapping rules.The dynamic failure probability and key causes of emergency disconnection were studied,and the prevention measures were put forward from the design of drilling riser system,drilling operation,emergency disconnection test and operation,and other aspects to reduce the probability of emergency disconnection failure.The case analysis was carried out by taking No.8 drilling platform in the South China Sea as the research object.The results showed that the probability interval of riser’s emergency disconnection failure in 1 year was 0.075 7 to 0.105 0,and the main reasons causing the emergency disconnection failure were the typhoon,unreasonable disconnection moment,inadequate overpull force,large inclination angle of wellhead and internal wave.The assessment results of the model were consistent with the actual situation,and the method can be applied in the risk assessment on the emergency disconnection failure of drilling riser.