Risk assessment is an effective and commonly practiced process in industry, including oil and gas sector, as a basis for designing new pipeline terminals and stations and managing integrity of existing facilities. A holistic risk assessment method, which could be qualitative or quantitative, includes both the likelihood and consequence assessments of an undesired event. Prior to 2015, Enbridge Pipelines employed a qualitative risk assessment algorithm to assess the likelihood and consequence of a failure of liquids pipeline facilities.
Over the past decade Enbridge has identified a number of shortcomings with the qualitative approach, necessitating the development and use of Quantitative Risk Assessment (QRA) to support consistency and defensibility in risk-informed decision making. A QRA requires rigorous quantitative algorithms to measure public and environmental safety, and potential business consequences of an undesired event at a facility. While significant literature has been produced, and considerable effort has been expended to quantify the potential impacts of a flammable product release on public safety, very limited work has been done on the quantitative measurement of environment related impacts. In particular, limited research has been successful in aggregating environmental consequences, public safety and business consequences to estimate the total consequence of a liquid hydrocarbon release within a pipeline facility.
The consequence assessment of an unwanted event conducted through QRA can be combined with the associated likelihood to provide a quantitative measure of risk. This risk level may be used to support organizations in making risk informed decisions and in analyzing and treating facility risks, specifically in the:
• Identification of top risk facilities and high consequence functional areas;
• Identification of assets posing the most risk and worst case consequences;
• Understanding of system reliability risk and opportunities to optimize facility operation;
• Prioritization of facility maintenance projects in the capital and operating budget processes;
• Supporting regulatory requirements and expectations;
• Presentation of risk down to the equipment or component level; and
• Understanding of residual risk and achieved risk reduction.
This paper describes the development of a consequence model that monetizes the quantitative measure of public and environment safety, and potential business losses for a liquid product release at pipeline facilities. The proposed model characterizes the severity of impact of released product, expressed in dollars per event, as a function of system volume, proximity and category of receptors, asset location, and available controls.