水下卧式采油树安装过程定量风险评估

Quantitative risk assessment over the so-called “subsea Christmas tree” installation

针对水下卧式采油树安装过程风险大及其风险评估缺乏分析数据难以进行定量计算的问题,在事故树定性分析的基础上,建立了AHP-TOPSIS综合评判指标体系,对水下卧式采油树的安装过程进行风险评估。根据定性分析结果得出定位、锁紧、密封、下放工具与组件连接失效4个关键事件及其影响因素。通过AHP法确定影响因素的权重,结合TOPSIS原理构建AHP-TOPSIS综合模型,计算各个组件下放失效的综合优势度。采用AHP-TOPSIS方法实现了多风险因素的定量风险评估。对水下卧式采油树安装过程风险进行评估,结果表明,树体、油管挂、阻塞器和内帽的风险值相近,油管挂风险值最高,外帽的风险值最小。

In answering to the shortage of subsea Christmas tree installation risk analysis statistics,the given paper is inclined to develop an evaluation indicator system on the subsea Christmas tree installation AHP-TOPSIS（ Analytic Hierarchy ProcessTechnique for Order Preference by Similarity to Ideal Solution） on the basis of FTA（ Failure Tree Analysis） system. In doing so,we have made an investigation of the chief influential factors,such as the crucial failure events,the position locking,the sealing security situation,the connection of the tools and components,as well as the related safety measure taken. It is just based on the comprehensive analysis of the aforementioned installation and equipment adopted situation in-situ,a quantitative and qualitative evaluation results of FTA have to be provided in terms of their soundness and trustfulness in addition to weighing the impact factors. What is more,full account should also be taken into a comprehensive AHP-TOPSIS model that pays enough attention to the dominance of the equipment installation process. Furthermore,all the influential factors are to be carefully weighted and scored by the groups of experts for their approval. Besides,the actual risk assessment process for the subsea horizontal Christmas tree installation demonstrates that the order of the risk evaluation should be done in the following descending order： tubing hanger spool body crown plug = inter tree cap debris cap. Comparing the installation risk levels,we can find that there may exist approximately equal risk level for the spool body,the crown plug,and the inter tree cap. Or,more specifically speaking,it can be said that the tubing hanger risk should generally be regarded as the greatest whereas the debris cap may be the lowest. Since the tubing hanger is the key piece of equipment,its installation may involve the most complicated steps. Even if the components share the same functions,for example,the crown plug and inter tree cap,it is also necessary to make their design well matched with each other in the related standards. For example,if the debris caps fail to be properly installed,it is likely to lead to serious and even disastrous consequences,which demands us to take into detailed accounts the likely failure liabilities even if they may be minus. Thus,it can be seen that this paper is qualified enough to provide an up-to-date method for quantitative risk assessment for the subsea tree installation,especially the detailed guide for the offshore installation process in terms of effective quantitative risk assessment of the multiple factors.