深水井作业相对于陆地和浅海作业具有更大的挑战和不确定性,其作业环境恶劣、储层流体不易控制,极易发生井涌、井喷和泄漏等事故.对深水井完整性失效分析是减小上述事故发生可能性的关键.基于安全屏障理论和事故树理论,提出了一种适用于深水井完整性失效分析的SBFT分析方法.以起出防喷器(BOP)、下入水下采油树的作业过程为例,建立了安全屏障模型和事故树模型,经计算得井完整性失效概率与统计值相符.运用最小割集和最小径集分析了井完整性失效的可能途径和最佳控制方案.通过3种重要度分析确定了该过程的最薄弱环节是油管悬挂器,主要失效因子为CO2冲刷腐蚀以及密封部件损坏,为深水井事故调查及事故隐患整改提供了理论依据.%Deepwater well operations face much more challenging conditions and uncertainties than onshore and shallow water operations. The accidents such as kick, blowout and leakage are likely to occur under the harsh environment conditions and the unintentional flow from the formation. The key to reducie the occurrence possibility of such incidents is failure analysis of deepwater well integrity. In this paper, an integrated risk analysis methodology, SBFT, on basis of safety barrier theory and Fault Tree Analysis ( FTA) was proposed to analyze failure mechanisms of deepwater well integrity. A case study on pulling BOP and landing subsea production tree was presented to show how this method can be applied to this field. Safety barrier (SBE) model and a fault tree model were established. The failure probability of well integrity was consistent with the actual statistics. The paths of the failure and the optimal controlling schemes were analyzed by using the least cut-set and the least path-set. The calculation and analysis of 3 importance magnitudes by fault tree for basic events show that the weakest link in this process was tubing hanger , the main failure factors are CO2 erosion corrosion and sealing components damaged. It provides theoretical support for accident investigation and risks rectification of deepwater wells to the greatest extent.
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