The primary function of monitoring systems is to ensure the operational integrity and safety of the system being monitored. Continuous monitoring provides timely information on the state of the monitored system as well as early warning of anomalies that might lead to catastrophic failures. One of the leading sensing technologies that is gaining wide acceptance in the industry is fiber optic-based sensing technology. This technology enables the fiber optic cable to act as a sensor, providing continuous sensing with wide sensing coverage and advanced warning capabilities in real-time. When utilized in a distributed configuration, it detects changes in vibration, strain, and temperature along the monitored object. The strain on an offshore crude pipeline may indicate the presence of fractures; recognizing them early can prevent structural collapse, which might lead to a leak and, eventually, an oil spill, inflicting environmental damage. This chapter presents a theoretical analysis of fiber optic-based sensing and its practical applications.
F AILURE OF LEAK DETECTION SYSTEM to detect hydrocarbon releases from an offshore pipeline can have devastating effects on operation and environment. Moreover, the failure consequences may bring about excessive financial losses and could threaten the survivability of the operating company in the market. This paper provides a risk-based assessment methodology to assess the reliability and the level of risk for offshore pipelines and their leak detection systems. The assessment outcome is compared against a target or acceptable risk level that can help decision makers to decide the most feasible action for averting risk.
Leak Detection Systems play a major role in enhancing reliability and operability of oil and gas pipelines. They have the functional capabilities to detect, locate and quantify leaks before they can cause drastic effects to environment and operation. The performance of Leak Detection Systems is typically affected by three different failures that have severe consequences, namely, delayed detection, missed detection and false detection of a leak. These failures pose a financial burden on operating companies. Missed detection leads to oil spill and exposes operating companies to financial risk and destroyed image while false detection results in unnecessary deployment of personnel and equipment. To insure operation continuity and maintain safe environment, Leak Detection Systems should be assessed at regular basis. To fulfill this need, a probabilistic performance assessment scheme based on limit state approach for Fiber Optic Leak Detection System (LDS) has been developed. The inherent uncertainties associated with leak detection and reporting capabilities are modeled to determine the LDS detection failure probability that combines two failure events, missed detection and delayed detection. Moreover, the probability of false detection is derived in terms of the lowest detectable change, the threshold. These three parameters establish the basis for an overall assessment scheme that can be used at any time to provide an up to date assessment about the Leak Detection System. The results will serve as the basis for deciding the actions that need to be taken to upgrade, repair or replace the system components or the system as a whole. The proposed assessment scheme has been applied to a case study to demonstrate its usefulness and feasibility.
The failure of systems to meet the specified requirements may have adverse effects on their integrity and reliability. The systems could be mechanical, electrical, structural, telecommunications, or electronic that are designed and built to satisfy certain technical specifications and operational requirements. Failure does not necessarily mean the occurrence of a disaster or damage to the system, but also the degraded performance of such systems is considered a failure. One of the essential indicators of the performance and reliability of a system is the probability of failure which is computed by probabilistic methods. One of these methods is the first-order reliability method (FORM). Using FORM to estimate the probability of failure of systems having a nonlinear or a higher-order performance function may provide inaccurate results that may lead to misleading conclusions. To resolve this issue, the second-order reliability method (SORM) is recommended to estimate the probability of failure. This chapter presents commonly used probabilistic approximation methods to estimate the probability of failure for nonlinear performance functions. Illustrative examples to demonstrate the application of these methods are provided at the end of the chapter.
Failure of a system or a component of a system is and has been a major concern to systems' operators and owners. Failure could be traced back to different causes and may take different forms and shapes. It may result from software malfunction, hardware degraded performance, human error, sabotage, environmental as well as other external factors. There are various techniques found in the literature that can assist in the analysis of failure. These techniques comprise deterministic and probabilistic techniques. Deterministic techniques ignore the variability and uncertainties of the variables in the analysis which may lead to unsatisfactory and inaccurate results. While probabilistic techniques produce accurate and an all-inclusive result because they incorporate the variabilities and uncertainties in the analysis. The focus of this chapter is to present commonly used probabilistic failure analysis techniques and their mathematical derivations. Examples to enhance the understanding of the concept of failure analysis are also presented.
Oil and gas condition monitoring systems play a major role in maintaining the operability, integrity, and reliability of oil and gas infrastructure. A leak detection monitoring system (LDS) constitutes an important member of these systems. The main function of this system is to detect the occurrence and location of hydrocarbon leakages in a timely manner before the leaked products can cause a devastating effect on production, health, safety, and the environment. To ensure the continuity of operation and the safety of personnel as well as the environment, this system should be assessed on a regular basis. Traditionally, a deterministic approach is adopted to assess such systems. A deterministic assessment does not consider uncertainties or random variabilities that are inherent in the performance parameters. Thus, it produces results that may not characterize the actual situation of the system or its circumstances. To tackle this issue, it is proposed to use a probabilistic approach to assess the performance since it allows the incorporation of any uncertainties or random variabilities that may exist in the assessment. Hence, a quantifiable probability of failure can be estimated. Once the probability and consequences of failure become known, risk can be easily estimated.
A complete assessment of risk cannot by obtained without incorporating the probability of failure of the pipeline itself. The major research activities include, formulation of the LDS probability of detection and false detection for a single point along the oil and gas transport component; development of a probabilistic performance assessment scheme for the entire LDS along the oil and gas transport component using a limit-state approach; application of probabilistic methods to determine the probability of failure and the remaining life of the oil and gas transport component and development of a risk-based assessment methodology to determine the risk associated with the simultaneous failure of the LDS and the oil and gas transport component (i.e., pipelines). These major research components establish the foundation for an overall evaluation scheme that can be used to provide an up-to-date assessment of the oil and gas transport components and the LDS. The outcome of the assessment can serve as a basis for a well-informed decision-making process that enables the decision makers to determine the best strategy for assessing and maintaining the integrity of the evaluated systems.
Failure Analysis - Structural Health Monitoring of Structure and Infrastructure Components is a collection of chapters written by academicians, researchers, and practicing engineers from all over the world. The chapters focus on some developments as well as problems in structural health monitoring (SHM) in civil engineering structures and infrastructures. The book covers a variety of multidisciplinary topics, including SHM, risk analysis, seismic analysis, and various modeling and simulation methodologies. This book is an excellent resource for undergraduate and postgraduate students, academics, and researchers across a wide variety of engineering disciplines, as well as for practicing engineers and other professionals in the engineering industry.
Abstract The consequences of subsea crude pipeline failure drastically affect the continuity of oil supply and the ability of operating companies to meet market demand. Moreover, it reduces clients’ confidence and reliance on operating companies. There are mainly two types of failures that severely affect the integrity and operability of a pipeline. These are the leakage caused by gradual thinning of the pipeline due to corrosion and the leakage caused by a rupture pressure. The first form of failure results in a constant slow leakage that go over time without being noticed. While the second form of failure takes place without warning which makes the restoration effort extremely difficult and time consuming. Both forms of failure result in delayed production, environmental damage, legal claims as well as financial losses that operating companies could incur. Moreover, leaked oil products adversely impact other industries which bring these industries into a halt. Such industries may include fishery, maritime transportation, and tourism industries. This paper presents a method for predicting the financial losses that a company could incur in the event a corroded pipeline undergoes the abovementioned failures. Basically, this method can be used as a standard estimating tool for predicting the financial losses if such events occur.
Insuring the integrity of subsea process component is one of the primary business objectives for oil and gas industry. One of the systems used to insure reliability of a pipeline, is the Leak Detection System (LDS). Different leak detection systems use different technologies for detecting and locating leaks that could result from pipelines. One technology in particular that is gaining wide acceptance by the industry is the optical leak detection systems. This technology has great potential for subsea pipelines applications. It is the most suited for underwater applications due to the ease of installation and reliable sensing capabilities. Having pipelines underwater in the deep sea present a greater challenge and a potential threat to the environment and operation. Thus, there is a need to have a reliable and effective system to provide the assurances that the monitored subsea pipeline is safe and functioning as per operating conditions. Two important performance parameters that are of concern to operators are the probability of detection and probability of false alarm. This article presents a probabilistic formulation of the probability of detection and probability of false detection for fiber optic LDS based systems.
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