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DAS technology ensures pipeline safety


Pedro Barbosa, senior product manager - pipelines, at Fotech Solutions, a bp Launchpad company, explains why focusing on pipeline integrity is more important than ever

He outlines how operators can use advanced technologies such as distributed acoustic sensing (DAS) to improve pipeline safety.

Pipeline integrity is a key concern for oil and gas operators wanting to ensure that pipelines are being operated in a safe and reliable way. Keeping pipelines free from defects and damage, so they can continue to transport their contents, without incident, is critical to preventing harmful substances from being released into the environment and for protecting the population against potential incidents. Even the smallest oil and gas leaks can cause major environmental damage and the costs for clean-up can easily run into millions.

For example, the incident in Refugio Bay, off the West Coast of the United States, when, on 19 May 2015, 541,000 litres of crude oil spilled onto one of the most biologically diverse coastlines in the world. The cause of the leak was identified as being extensive corrosion, but unfortunately, it remained undetected until it was too late. Local pipeline workers did not know about the leak until they were notified by the state parks staff that there was oil in the water . Plains All American Pipeline L.P. and Plains Pipeline L.P. agreed to modify operations to prevent further spills, and to pay US$24mn in penalties, plus US$22.3mn in natural resource damages, US$10mn for natural resource damage assessment costs and US$4.26mn for Coast Guard clean-up costs. The overall cost of the clean-up, including expected legal claims and potential settlements, was approximately US$257mn. 

So, what can operators do to prevent such incidents and what are the best ways to ensure pipeline integrity and faster leak detection? There are a number of approaches to take that include considering the latest technologies, following the latest oil and gas pipeline standards and guidance, and establishing an integrity management plan

While it is common practice to install automatic leak detection systems in pipelines, there are several limitations with traditional systems, particularly internal-based systems, due to their inability to detect small leaks and, when detected, to locate them accurately. This happens because there is no direct measurement of the leak phenomenon, but rather the leak is inferred from mass balance evaluations using parameters such as flow, pressure, temperature, etc.

DAS technology, however, can monitor pipelines accurately for both leak detection and third-party interferences, including disturbances relating to attempted theft. It uses photonics, which essentially turns a fibre optic cable running alongside a pipeline network into thousands of vibration sensors able to detect any disturbances along the length of the pipeline, even over hundreds of kilometres, and in real-time.

DAS technology, such as Fotech Solutions’ LivePIPE solution, sends thousands of pulses of light along the fibre optic cable every second and monitors the fine pattern of light reflected back. When acoustic or vibrational energy – such as that created by a leak or by digging – creates a strain on the optical fibre, it changes the reflected light pattern. By using advanced algorithms and processing techniques, DAS analyses these changes to identify and to categorise any disturbance. Each type of disturbance has its own signature and the technology can tell an operator, in real-time, what happened, exactly where it happened and when it happened.

The American Petroleum Institute (API), the benchmark for standards on operational and environmental safety, efficiency and sustainability, plays a vital role in promoting the performance standardisation of leak detection systems. Two key standards that provide pipeline operators with critical guidelines to support early and accurate leak detection, and which are essential for improving integrity and safety, are API RP 1130 Computational Pipeline Monitoring for Liquids and API RP 1175 Pipeline Leak Detection-Programme Management. These standards were updated in April to now include external leak detection systems such as those based on fibre-optic sensing technologies. The standards provide specific performance metrics that pipeline operators can follow. For example, RP1175 indicates targets and performance metrics that an operator might apply to a pipeline. While internal systems should detect leak sizes of +/-200 barrels/h with a location accuracy of +/-5 miles (steady flow), external systems should detect leak sizes of +/-2 barrels/h with a location accuracy of +/-10 meters (steady flow). 

Another important step in improving integrity is to have a robust integrity management plan. In the US, the Pipeline and Hazardous Materials Safety Administration (PHMSA) provides regulations for pipeline operators to comply with to prevent pipeline leaks and corrosion. One of the requirements for operators of hazardous liquid, natural and other gas transmission and distribution pipelines is to develop and implement comprehensive integrity management programmes. When prescriptive regulation is not in place, pipeline operators may choose to follow risk –or performance-based approaches, recognised standards, RP’s and best practices, for example, API RP 1160 Pipeline Integrity Management Standard for Hazardous Liquid Pipelines and ASME B31.8S Managing System Integrity of Gas Pipelines

Integrity management plans are a documented and systematic approach to ensure the long-term integrity of pipelines. The process serves to assess and mitigate risks in an effort to reduce both the likelihood and the consequences of incidents and to optimise safety and performance. 

Older concepts of integrity simply focussed on pipeline maintenance and inspection. It considered primarily a pipeline's physical qualities, support systems and the administration of an operator's inspection programme. Integrity management, however, now takes a wider view, considering the environment as well. The regulations of hazardous liquid pipelines stipulate that oil and gas companies routinely assess pipelines in locations where a pipeline leak or failure could have significant adverse consequences and where there is a higher risk of serious public or environmental safety.

Pipeline integrity is a critical topic for operators, and one that is continually evolving as oil and gas companies look to improve their practices and to operate to the highest safety levels. Over the past 40 years, integrity management has progressed from prescriptive visual inspection and assessment, to include risk-based integrity management using real-time data. Not only can a well-managed pipeline integrity plan help operators identify and reduce safety risks before they escalate, but also play a major role in both achieving operational excellence and extending the life of ageing assets.

With pipeline integrity more important than ever, it is increasingly crucial that industry standards and legislation are applied. It is also essential that any regulations and standards are aligned with and reflect new technology advances. Only then can integrity ultimately be enhanced.

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