New quantitative risk prediction method of deepwater blowout: Case study of Macondo well accident

Risk assessment is an effective technology to prevent blowout accidents in deepwater drilling. In this paper, a new quantitative risk assessment method named Barrier-Index Risk Prediction (BIRP) method is proposed, which is based on the reliability analysis of safety barriers and risk index evaluation to predict the deepwater blowout risk, and the case of Macondo well accident is used for calculation and analysis. According to BIRP method, the deepwater blowout accident is the common result of the occurrence of the initial event (well kick) and the failure of deepwater well control system (consists of safety barriers), while the states of well kick and well control system is determined by their Risk Influence Factors (RIF). The parameter of risk Increment Range (IR) is introduced to calculate the deepwater blowout risk. Finally, the Early Risk Warning Signal of deepwater blowout is established to describe the blowout risk of target deepwater well. The analysis of control factors confirms the inevitability of Macondo well accident and the accuracy of BIRP method. BIRP method focuses on the impact of RIFs, and establishes the Risk Index Evaluation System to assign indexes for them to quantify their risk status; it pays attention to the cooperation and trust between human and machines, and can predict the blowout risk status of the target deepwater well in each stage of deepwater drilling & completion engineering in real time. The BIRP method is suitable for the risk assessment of deepwater blowout and can provide theoretical guidance for its safety management.