The synthesis and evaluation of two new gas hydrate kinetic inhibitors

Abstract

Gas hydrate plugging is a common yet hazardous problem during oil and gas reservoir exploitation, compelling the petroleum industry to invest substantial resources annually in mitigation strategies. Two novel hydrate kinetic inhibitors (HKIs), a PVP derivative (PVP-DP) and a PVCap derivative (PVCap-DP), were synthesized and systematically evaluated. Structural characterization by FT-IR, NMR, and TG analyses confirmed increased molecular weights and the introduction of additional polar functional groups relative to the present polymers. In pure water at a subcooling temperature of 6.2 K and a concentration (C_p) of 1 wt%, the methane hydrate induction times (I_h) for PVP-DP and PVCap-DP were 358 min and 395 min, respectively. These values significantly exceed those observed in distilled water (23 min) and in systems containing commercial HKIs, such as PVP (138 min) and VC-713 (272 min). Increasing C_p to 3 wt% further prolonged I_h to 911 min and 964 min, respectively. Even at a higher subcooling of 8.4 K, I_h remained considerable at 126 min and 158 min, demonstrating sustained inhibition under more severe thermodynamic driving forces. Synergistic effects were observed when HKIs (3 wt%) were combined with glycol (1 wt%), resulting in I_h values of 230 min and 268 min. Increasing the glycol concentration to 3 wt% maintained a strong inhibition performance, with I_h values of 211 min and 238 min even at a subcooling of 9 K. In addition, both derivatives exhibited effective inhibition in water/diesel emulsion systems. At 6.2 K subcooling, the PVP-DP (3 wt%)–water/diesel emulsion system achieved an I_h of 404 min, which was markedly longer than that of the uninhibited water/diesel emulsion (51 min), although the emulsion phase moderately reduced the inhibitor efficiency. Overall, PVP-DP and PVCap-DP demonstrate strong kinetic inhibition performance against the formation of natural gas hydrate in both aqueous and emulsion systems, indicating promising application potential in complex production environments.