Underinhibited MEG Regulates Natural Gas Hydrate Plugging Regimes and Kinetic Responses in a Visual Rocking Cell

Abstract Underinhibited monoethylene glycol (MEG) operation is increasingly considered for hydrate management in natural gas production and transportation, but the associated plugging risk depends not only on hydrate formation extent but also on how hydrates grow, agglomerate, and evolve into flow-blocking structures. In this work, hydrate formation and plugging experiments were conducted in a high-pressure visual rocking cell to examine the effects of MEG concentration, temperature, and pressure on natural gas hydrate plugging behavior. Hydrate plugging in underinhibited MEG systems was classified into three regimes: rapid plugging, delayed plugging, and stable slurry. The delayed plugging regime was further divided into wall-growth and local-accumulation pathways. At 6.6 MPa, increasing temperature from 2 to 6 °C narrowed the rapid plugging regime from 0–15 wt % MEG to 0–5 wt % MEG and shifted the stable slurry regime from 30–35 wt % to 20–25 wt % MEG. In contrast, at 4 °C, increasing pressure from 6.6 to 11 MPa expanded the rapid plugging regime from 0–10 wt % to 0–20 wt % MEG and nearly eliminated the stable slurry regime. Distinct kinetic signatures were also observed, with rapid plugging generally showing higher and more concentrated peaks in the instantaneous gas consumption rate. These results demonstrate that underinhibited MEG regulates hydrate plugging by altering hydrate formation, particle agglomeration, wall adhesion, and kinetic pathways toward flow blockage, providing experimental insight into hydrate-control strategies for natural gas flow assurance.