Risk Assessment of Subsea Pipeline due to Installation and Operation of Single Point Mooring (SPM)

Abstract

Abstract Offshore exploration facilities located in remote areas require high investment and high operational cost, the assets are classified as vital assets for the companies. The careful study and examination is therefore required to ensure that the risk of the facility is acceptable. Offshore exploration used subsea pipelines that has several risks if the accident occurs. Based on historical data, most of subsea pipelines failures are caused by third party factors (dropped anchor, dragged anchor, and ship sinking). This paper examines risk assessment of subsea pipelines due to installation and operation of SPM is assessed used DNVGL RP F107 standard and numerical simulations. Frequency is assessed by using Bayesian Network methods. Whereas the consequences were assessed by using calculations on the DNVGL RP F107 standard and FEM simulation. The results of frequency and consequences are mapped within a risk matrix according to DNVGL RP F107. Based on the calculation, the frequency of all types of vessels is less than 10-5 (rank 1). While the lowest consequence was rank 3 with a dent/diameter is 12.32% and the highest was rank 5 (>20%) which can damage the subsea pipelines. The risk matrix shows that the risk level are in acceptable and ALARP condition. Acceptable obtained by frequency in rank 1 and the consequence in rank 3 and 4. While ALARP obtained by frequence rank 1 and consequence rank 5. Although it is not mandatory for mitigation, it is recommended to provide the subsea pipeline with external protection. Rock dumping is recommended as external protection for subsea pipelines due to the good ability to protect the subsea pipelines and it has lower cost compared to concrete mattress.