A Copula-Bayesian approach for risk assessment of decommissioning operation of aging subsea pipelines

Currently, many subsea pipelines are reaching their design life, and most of them need to be decommissioned due to the serious structural degradation. However, the decommissioning operation of aging subsea pipelines is a challenging task due to the harsh environmental and technical complexity. An efficient risk assessment is important to ensure the safety of pipeline decommissioning operation. This paper presents a Copula-Bayesian approach for risk assessment of decommissioning operation of subsea pipelines, which can capture the complicated interactions among risk factors of decommissioning operation of subsea pipelines. The correlations among risk factors are described qualitatively and quantitatively using the percentile cobweb plot and correlation coefficients. The critical risk factors in decommissioning operation can be found by correlation analysis. Finally, the failure probabilities of pipeline decommissioning operation are estimated. The methodology is tested by a case study of decommissioning operation of a subsea pipeline in the South China Sea. The results indicate that the improper cutting technique, operation error, and unqualified construction are the critical risk factors, and the failure probability of decommissioning operation is positively correlated with the update on the critical risk factors. The methodology can be a useful tool for risk-informed decision-making in subsea pipeline decommissioning operation.