Analysis of the Effect of Pipeline Inclination on Hydrate Growth Mechanisms

Hydrate clogging has historically posed significant challenges to the exploitation of deep-sea oil and gas reserves. The complexity of the pipeline-laying environment, characterized by an intricate seabed topography, often results in sloping pipelines. In such configurations, gas–liquid two-phase flow can lead to segment plug flow, which accelerates hydrate formation and jeopardizes the safety of natural gas transmission pipelines. To enhance the safety of transportation systems, it is essential to investigate the influence of inclination angles on hydrate growth, thereby mitigating potential flow blockage risks. This study employs a high-pressure visual-flow pipeline system to systematically examine the effects of varying pipeline inclination angles (0, 5, 10, and 15°) on the hydrate generation rate. Natural gas solubility was predicted under hydrate formation conditions for a better understanding of gas-hydrate interactions and phase-transition behaviors, to optimize the generation conditions, and to assess the thermodynamic stability of hydrates. The findings reveal that the inclination angle significantly affects the gas phase behavior, alters fluid flow patterns, enhances gas–liquid mass transfer, and consequently accelerates hydrate generation. Furthermore, this study proposes the utilization of mixed slurry density as a proactive early warning indicator for monitoring hydrate formation.