基于事故树的钻柱失效分析方法

针对复杂地质条件下钻柱失效事故频发、防控措施效果不理想的现状，应用图论中的事故树分析方法，在演绎钻柱失效诱因与防控措施逻辑关系的基础上，建立了钻柱失效事故树模型。运用最小割集与径集分析了钻柱失效的路径和最优防控途径，并以川东北地区钻柱失效为例进行了实例分析。结果表明，该地区钻柱失效概率为56.81%，事故树定量计算结果与实际统计值相符合，证明基于事故树的钻柱失效分析方法切实可行，事故树结构合理，计算结果真实、可靠。同时，通过计算事故树基本事件的3个重要度，为制定钻柱失效防控对策提供了理论依据，增强了防控措施的针对性和实用性。

A failure analysis of drill string based on fault tree

In view of frequent occurrences of drill-string failure under complicated geological conditions and the less effectiveness of preventive measures,the present paper applied the fault tree analysis (FTA) of the graph theory to interpret the logical relationship of an inducement of drill-string failure and related control measures,established a fault tree model for drill-string failure,and analyzed paths of drill-string failure and the optimal prevention ways by using the least cut-set and the least path-set.The drill-string failure analysis in the northeastern Sichuan exploration area was taken as a case study.The results indicated that the probability of drill-string failure in the study area obtained by quantitative analysis of fault tree was 56.81%,consistent with the actual statistics.The case study proved that the drill-string failure analysis based on FTA was feasible,the structure of the fault tree involved was reasonable and the calculation results were truthful and reliable.Meanwhile,the calculation of importance magnitude by fault tree for basic events provided the drill-string failure prevention and control with a theoretical basis,which enhanced the pertinence and practicality of prevention and control measures.