Evaluating the likelihood of pipeline failures for future offshore CO2 sequestration projects

This study sets out to understand the likelihood of pipeline failures associated with offshore CO2 pipelines for sequestration projects by evaluating the safety track record for offshore natural gas pipelines, using a 20-year detailed dataset available from the agency that regulates offshore pipelines in the US. Based on this analysis, it is concluded that the risks of future fatalities from offshore CO2 pipelines are on the order of 10−7 km yr, a level of risk that most authorities would see as negligible. The rate of serious incidents reported for offshore U.S. natural gas pipelines have been significantly increasing over the last decade. Our analysis suggests that this is an artifact correlated with increasing natural gas prices, which results in more incidents exceeding the $US 50,000 damage criterion. The dominant risk of injuries and fatalities in offshore natural gas pipelines come from fires on offshore platforms. The rate of failure for offshore transmission pipelines is estimated as 5 × 10−4 versus 3 × 10−4 km yr for gathering pipelines. This may be explained by the difference in average age (27.7 for gathering and 32.9 years for transmission), or because transmission pipelines are operated closer to their maximum allowable operation pressures than are offshore gathering pipelines. The fatality rate for offshore natural gas pipelines is essentially the same as for those onshore however none of the recorded deaths in the data set were related to failures of pipeline integrity. As a result of the minimal exposure of workers (and the general public), to the impacts of CO2 releases in the offshore environment it is argued that the fatality rate associated with CO2 pipelines will likely be lower than for natural gas pipelines. Assuming that a future offshore CO2 sequestration project is based on sea floor injection and control systems, risk mitigation efforts clearly should focus on the near shore portion.