Challenges in Accurate Detection of the Main Cause of Blockage: Case Studies

Abstract Flow blockages in oil and gas pipelines are critical challenges that can lead to severe operational disruptions and significant costs of blockage removal and production loss. These blockages may arise from various sources, including wax deposition, asphaltene precipitation, gas hydrate formation, and ice. Accurately identifying the root cause of a blockage is essential for implementing effective remediation strategies. This paper presents a detailed study of the challenges associated with the accurate detection of blockages in oil and gas production systems, focusing on three real-world case studies. The first case study examines a subsea pipeline where initial suspicions of hydrate formation were complicated by the presence of ice, requiring advanced thermodynamic modelling to accurately diagnose the issue. The second case study involves a subsea light oil pipeline where wax deposition, rather than the initially suspected hydrate formation, was identified as the root cause of the blockage after comprehensive phase equilibrium analysis. The third case study discusses a chemical process plant where a blockage in a Cold Box, initially attributed to hydrate formation, was later confirmed to be due to ice, as revealed by a combination of phase boundary analysis and methanol injection testing. The findings underscore the importance of precise phase equilibrium modelling and a comprehensive understanding of the system's thermodynamic conditions in diagnosing and resolving flow assurance problems.