Hydrocarbon pipelines are high value assets which have to be kept operating at risks as low as reasonably practicable. An integrated Pipeline Integrity Management System (PIMS) environment enables practices that result in more efficient data maintenance and information reliability while providing consistent application of integrity procedures including risk assessment and risk management. Risk assessment can be done by adopting qualitative, semi-quantitative or quantitative methodologies. As pipeline operators progressively adopt operating strategies of continual risk management and risk reduction with a view to minimizing total expenditures within safety, environmental, and reliability constraints, the need for quantitative assessments of risk levels and setting of risk tolerability criteria is becoming evident. The advantages of quantitative risk assessment are that it is measurable and helps to identify specific segments in a pipeline where the mitigation measures should be applied. Hence a quantitative risk based approach is adopted by the operator for maintaining the pipeline system. The two components of risk are probability of failure and consequences of failure. The probability of failure is primarily driven by the nature of threats. The pipeline characteristics and operating conditions that increase the probability of failure change based on the threats and it is essential to identify and quantify those threats that increase the risk of a pipeline failure to effectively address the issue. The consequences of failure are primarily driven by loss of product and downtime of the asset which are subsequently dependent on three factors – (1) detection time, (2) isolation time and (3) repair time. This paper is a case study relating to a major producer in the Middle East on how they manage their pipelines and the role of risk assessment within their multiple pipeline integrity management system. It describes how software-assisted, data driven, quantitative risk assessment is utilized to identify and prioritize specific segments of the pipelines for risk mitigation. The paper explains the importance of gathering accurate data to conduct the quantitative risk assessment and how the risk model was developed in such a way that any anecdotal understanding of pipeline risks is avoided so that the risk results are essentially driven by facts and figures. The paper explains the organizational challenges faced by the operator when such a process is implemented, including the importance, in a large organization, of stakeholder engagement in the data gathering, risk assessment and decision making process and the methods adopted by the operator to overcome those challenges and obtain that engagement. The importance of implementing various company pipeline integrity management procedures and its role in ensuring collection of all the vital information in a timely manner, which can eventually be used for the pipeline risk assessments, are also explained. An overview of the risk model used is described including the various threat and consequence models. The criteria established for pipeline segmentation are also described in detail. Scenarios are provided, as examples, where the quantified risk of just one short segment increases the entire pipeline risk and how a small change in attribute and/or operating procedure can reduce the risk to an acceptable level. A discussion will also be included on how the risk engine supplies ‘what if' scenarios to demonstrate to what level the agreed mitigation activities reduce the risks prior to asset integrity expenditure. Thereby ensuring that mitigation actions are correctly directed and actually achieve their goal of maintaining pipeline risks at an acceptable level.
展开▼
