An Experimental Study on the Synergetic Effects of Kinetic and Thermodynamic Gas Hydrate Inhibitors

Gas hydrate can be inhibited by using hydrate inhibitors, such as thermodynamic inhibitors (e. g., methanol and salts) and kinetic inhibitors (KHIs; polymer based). The study of kinetic hydrate inhibitors is paid growing attention in recent years because of its low dosage and environment friendly features, but its application is restricted at high sub-cooling conditions. In this study, the combination of kinetic hydrate inhibitor (polyvinylcaprolactam based) and thermodynamic inhibitors (methanol and NaCl) was investigated in terms of the synergetic effect of the two types of hydrate inhibitors and the effects of pressure and sub-cooling time on the kinetic inhibition effect. The results show that the combined system has a good synergetic effect, which can make the KHIs to stand at higher sub-cooling conditions. The performance of polyvinylcaprolactam and methanol is better than that of polyvinylcaprolactam and NaCl, and the combined system can be also greatly affected by high pressure and long sub-cooling time.