System for Risk Assessment in Oil and Gas Pipelines Laying Process in Single Ditch Based On Quantitative Risk Analysis

In view of the vegetation reduction caused by the continuous construction of oil and gas pipelines, the pipelines have been designed to be laid in one ditch to reduce land occupation. However, owing to the small spacing between the pipelines, the fault correlation between pipelines has been proven to increase the potential hazard of adjacent pipelines and routing environments. The neglect of failure correlation in existing risk assessment methods leads to inaccurate results, which will lead to errors in maintenance decisions. Therefore, this paper proposed a risk assessment system for pipelines using this laying method. In the risk assessment, pipelines laid in one ditch (PLOD) were regarded as a series system relative to the routing environment. Therefore, by combining the reliability theory of the engineering system with mathematical induction, a functional relationship between the overall risk of the pipeline system and the risk of each pipeline was obtained. In addition, the probability of failure of each pipeline in the system was calculated using fuzzy set theory combined with Fault Tree analysis. Event tree analysis was used to classify all possible consequences of pipeline failures and then aggregated the results in monetary terms to assess the severity of the failure consequences. Finally, we combined the two parts into a butterfly diagram to implement risk management and pipeline control. Meanwhile, risk acceptance criteria and pipeline maintenance guidelines for risk analysis have been formulated. The system provides a complete risk assessment system for pipeline systems buried in a single trench, including risk identification, risk assessment and risk analysis methods essential to ensure the safety of pipelines and the environment when using this installation.