A risk analysis methodology to address human and organizational factors in offshore drilling safety: with an emphasis on negative pressure test

According to the final Presidential National Commission report on the BP Deepwater Horizon (DWH) blowout, there is need to “integrate more sophisticated risk assessment and risk management practices” in the oil industry. Reviewing the literature of the offshore drilling industry indicates that most of the developed risk analysis methodologies do not fully and more importantly, systematically address the contribution of Human and Organizational Factors (HOFs) in accident causation. This is while results of a comprehensive study, from 1988 to 2005, of more than 600 well‐documented major failures in offshore structures show that approximately 80% of those failures were due to HOFs. In addition, lack of safety culture, as an issue related to HOFs, have been identified as a common contributing cause of many accidents in this industry. ❧ This dissertation introduces an integrated risk analysis methodology to systematically assess the critical role of human and organizational factors in offshore drilling safety. The proposed methodology in this research focuses on a specific procedure called Negative Pressure Test (NPT), as the primary method to ascertain well integrity during offshore drilling, and analyzes the contributing causes of misinterpreting such a critical test. In addition, the case study of the BP Deepwater Horizon accident and their conducted NPT is discussed. ❧ The risk analysis methodology in this dissertation consists of three different approaches and their integration constitutes the big picture of my whole methodology. The first approach is the comparative analysis of a “standard” NPT, which is proposed by the author, with the test conducted by the DWH crew. This analysis contributes to identifying the involved discrepancies between the two test procedures. The second approach is a conceptual risk assessment framework to analyze the causal factors of the identified mismatches in the previous step, as the main contributors of negative pressure test misinterpretation. Finally, a rational decision making model is introduced to quantify a section of the developed conceptual framework in the previous step and analyze the impact of different decision making biases on negative pressure test results. ❧ Along with the corroborating findings of previous studies, the analysis of the developed conceptual framework in this paper indicates that organizational factors are root causes of accumulated errors and questionable decisions made by personnel or management. Further analysis of this framework identifies procedural issues, economic pressure, and personnel management issues as the organizational factors with the highest influence on misinterpreting a negative pressure test. It is noteworthy that the captured organizational factors in the introduced conceptual framework are not only specific to the scope of the NPT. Most of these organizational factors have been identified as not only the common contributing causes of other offshore drilling accidents but also accidents in other oil and gas related operations as well as high‐risk operations in other industries. ❧ In addition, the proposed rational decision making model in this research introduces a quantitative structure for analysis of the results of a conducted NPT. This model provides a structure and some parametric derived formulas to determine a cut‐off point value, which assists personnel in accepting or rejecting an implemented negative pressure test. Moreover, it enables analysts to assess different decision making biases involved in the process of interpreting a conducted negative pressure test as well as the root organizational factors of those biases. ❧ In general, although the proposed integrated research methodology in this dissertation is developed for the risk assessment of human and organizational factors contributions in negative pressure test misinterpretation, it can be generalized and be potentially useful for other well control situations, both offshore and onshore; e.g. fracking. In addition, this methodology can be applied for the analysis of any high‐risk operations, in not only the oil and gas industry but also in other industries such as nuclear power plants, aviation industry, and transportation sector.

根据针对英国石油公司（BP）深水地平线（Deepwater Horizon, DWH）井喷事故的最终总统国家委员会调查报告，石油行业亟需“整合更为成熟的风险评估与风险管理实践”。通过对海上钻井工业相关文献的梳理可见，现有多数已开发的风险分析方法未能充分且更关键的是，未能系统地阐明人为与组织因素（Human and Organizational Factors, HOFs）在事故致因中的作用。而1988年至2005年间一项针对海上结构物600余起有详细记录的重大故障的综合研究结果显示，其中约80%的故障均由人为与组织因素导致。此外，作为与人为及组织因素相关的议题，安全文化缺失被认定为该行业诸多事故的共同诱因。
本学位论文提出了一种集成化风险分析方法，用于系统评估人为与组织因素在海上钻井安全中的关键作用。本研究提出的方法聚焦于海上钻井期间用于确认井眼完整性的核心工序——负压试验（Negative Pressure Test, NPT），并分析了该关键试验被误判的潜在诱因。此外，本文还将探讨英国石油公司深水地平线事故的案例及其开展的负压试验情况。
本学位论文的风险分析方法包含三种不同的分析路径，三者的整合构成了本研究方法的完整框架。第一条路径为：将作者提出的“标准”负压试验与深水地平线作业团队开展的试验进行对比分析，以此识别两种试验流程之间存在的差异。第二条路径为构建概念性风险评估框架，用于分析前一步骤中识别出的流程偏差的致因因素——这些偏差正是负压试验误判的主要诱因。最后，本文提出了一种理性决策模型，用于量化前一步骤中构建的概念性框架的部分内容，并分析不同决策偏差对负压试验结果的影响。
结合既往研究的佐证性结论，本文对所构建的概念性框架的分析表明，组织因素是作业人员或管理层所产生的累积误差与存疑决策的根本原因。通过对该框架的进一步分析，可识别出对负压试验误判影响最大的三类组织因素：流程问题、经济压力与人员管理问题。值得注意的是，本研究提出的概念性框架所涵盖的组织因素并非仅局限于负压试验的范畴。其中多数组织因素不仅被认定为其他海上钻井事故的共同诱因，同时也是其他油气相关作业乃至其他行业高风险作业事故的常见致因。
此外，本研究提出的理性决策模型为已开展的负压试验结果分析提供了量化分析框架。该模型构建了一套分析体系，并推导得到若干参数公式，用于确定临界阈值，以此辅助作业人员判定所开展的负压试验是否合格。同时，该模型还可帮助分析人员评估负压试验解读过程中涉及的各类决策偏差，以及这些偏差背后的根本组织因素。
总体而言，尽管本学位论文提出的集成化研究方法是针对负压试验误判中的人为与组织因素贡献度风险评估而开发的，但该方法可被推广应用，且有望适用于其他海上及陆上的井控场景，例如水力压裂作业。此外，该方法不仅可应用于油气行业的各类高风险作业分析，还可推广至核电站、航空业、交通运输业等其他行业的高风险作业场景。