Effect of Diethanolamine, Mono-ethanolamine and Polyvinylpyrrolidone on Gas Hydrate Formation in a Simulated Offshore Environment

Gas hydrate formation remains a major flow assurance challenge in natural gas production and transportation systems, particularly under high-pressure and low-temperature conditions typical of offshore environments. This study investigates the combined effects of monoethanolamine (MEA), diethanolamine (DEA), and polyvinylpyrrolidone (PVP) on gas hydrate inhibition using a controlled hydrate flow-loop system. The work also considers the influence of iron filings as a representative corrosion-derived contaminant to simulate realistic pipeline conditions. Experimental evaluations were conducted at low inhibitor dosages (0.01–0.05 wt%) across multiple inhibitor combinations. The uninhibited system exhibited typical hydrate behaviour, characterised by rapid pressure decline and significant exothermic temperature increase, confirming hydrate nucleation and growth. The results showed that PVP, acting as a kinetic hydrate inhibitor, effectively delayed hydrate formation, while ethanolamine-based inhibitors contributed to thermodynamic suppression through interaction with water molecules. Among the tested systems, the MEA–DEA–PVP hybrid formulation demonstrated the highest inhibition performance under clean conditions, achieving a maximum inhibition efficiency of approximately 71% at 0.02 wt%, indicating strong synergistic interaction at low dosage. The MEA–PVP system also showed significant inhibition, with optimal performance at 0.02 wt%, while PVP alone achieved peak performance at a slightly higher concentration of 0.04 wt%. These findings confirm that hydrate inhibition is strongly concentration-dependent and that optimal performance occurs within a narrow low-dosage range. The introduction of iron filings reduced inhibition efficiency across all systems to approximately 60–62%, indicating that corrosion-derived particles promote heterogeneous nucleation and weaken inhibitor effectiveness. However, MEA-containing systems showed comparatively better performance under contaminated conditions, suggesting greater resilience to nucleation enhancement. Overall, the study demonstrates that hybrid thermodynamic–kinetic inhibitor systems provide effective low-dosage hydrate suppression, but their performance is significantly influenced by pipeline contamination. These findings provide important insights for optimising hydrate management strategies in real gas pipeline systems.