Operational risk assessment of oil and gas pipelines subjected to internal corrosion

Dao, Uyen (2023) Operational risk assessment of oil and gas pipelines subjected to internal corrosion. Doctoral (PhD) thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (10MB)

Abstract

Oil and gas transportation by pipelines serves as the primary means and the failure of pipelines is another fundamental concern. Under harsh operating conditions, oil and gas pipelines are vital infrastructures facing multiple damages, which increases the risk of metal degradation. Thus, the integrity of the pipeline is crucial to avoid various types of safety accidents at all levels which may cause fatality and substantial economic loss. To specify, oil and gas pipelines are mostly made of steel or stainless steel and are operated in harsh environmental conditions, due to the susceptibility of metallic characteristics of pipelines’ materials to corrosion, oil and gas pipelines are easily corroded. Thus, offshore oil and gas pipelines are facing a high rate of failures due to corrosion. The cost of corrosion-induced asset failure is rising, despite the vast investment in corrosion mitigation and control. Internal corrosion poses an integrity threat to oil and gas transportation, especially in harsh offshore environments. Internal corrosion including under-deposit corrosion (UDC), microbiologically influenced corrosion (MIC), localized corrosion, uniform corrosion, and erosion is considered one of the major contributing causes of pipeline failures in both onshore and offshore oil and gas industries, leading to significant financial losses. Predicting the internal corrosion rate is essential to ensure asset integrity and cost-effective transportation of oil and gas through pipelines. The study serves as an early warning guide for the integrity management of pipelines against internal corrosion. The work found that pipeline failures are caused by deposition parameters and microbial activities are predicted to be more frequent and dangerous than other factors. UDC and microbiologically influenced corrosion under deposits (UD-MIC) are found to be key contributors to pipeline system failure in the energy, marine, and petroleum industries. The operating parameters, environmental factors, material composition, microbial activity, and deposition parameters are major risk factors. The biotic factors also play a significant role in metal degradation in offshore domains, which enrich the UDC propagation and formation. Previous studies have not explored the interdependencies of such risk factors. Therefore, it is necessary to develop the probabilistic relationships among prevalent influencing risk factors of UDC and UDC-MIC and define their dependencies. This research seeks to study the complex interactions, controlling parameters, and characteristics that lead to UDCinduced failures. It is followed by analyzing the integrity of pipelines and proposing potential management solutions. More importantly, with the blooming of alternative energy. Hydrogen, a clean and emission-free fuel is considered a promising energy for the future. Hydrogen blending into existing natural gas pipelines is large-scale and low-cost for hydrogen transportation by pipelines that have the potential to spontaneously ignite Hydrogen leaks. Thus, safety for hydrogen pipelines is necessary to understand when we are talking about the hydrogen industry. The safety of blended hydrogen pipelines is also studied using the physics and mechanistic approach of hydrogen and pipeline degradation. Understanding the relationship between corrosion rate and hydrogen pipeline degradation can help ensure the safety of blended hydrogen pipelines. This work is also expected to explore further and assess how predictive maintenance can help increase the safety of hydrogen pipelines.

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