Effect of kinetic hydrate inhibitor and liquid hydrocarbon on the heterogeneous segregation and deposition of gas hydrate particles

Abstract

Segregation and deposition of hydrate particles observed in flowloop experiments are required to be investigated more thoroughly to understand the hydrate plugging mechanism in offshore flowlines. We used natural gas as gas phase and selected three different systems as liquid phase, which are pure water only, kinetic hydrate inhibitor added aqueous solution, and water+decane mixture, respectively. Hydrate formation process including onset and growth was studied by measuring the pressure, temperature, and torque changes in high-pressure autoclave. The obtained results suggest that poly-vinyl caprolactam (PVCap) solution shows elongated growth period than pure water until distinct torque change is observed, which also indicates the suppressing effect of PVCap on the growth of hydrate crystals. However, the presence of decane as continuous liquid phase enhances the deposition of hydrate particles on the wall. The torque change with conversion to hydrate used in this study is found to be useful to classify the hydrate formation process into three different regions.