Development of a Risk-based Integrity Model for Offshore Energy Infrastructures — Application to Oil and Gas Pipelines

Asset integrity management (AIM) is crucial at each stage of offshore energy development in order to maintain the integrity and enhance the safety of critical assets. Risk-based integrity is a widely used approach in AIM which aims to assess the potential risks of infrastructure damage, on the basis of likelihood of failure and magnitude of consequences. This paper develops a risk-based integrity model for offshore energy infrastructures with particular application to subsea oil and gas pipelines. The likelihood of failure is estimated using the Bayesian prior-posterior analysis as well as expert elicitation methods. The consequences associated with failures are also evaluated in terms of a 'cost' function which includes the costs of inspection, maintenance and repair. Our presented model is then applied to assess the potential risk of damage to an oil export pipeline. The results indicate that 'corrosion' is the most common cause of failure for pipelines, followed by external influences and human and operational errors. In accordance with the consequence analysis carried out, cost of inspection and preventive maintenance is evaluated to be significantly less than the costs associated with pipeline replacement. Finally, three mitigation strategies are suggested to minimise the risks of pipeline damage.