Effect of dodecyl dimethyl benzyl ammonium chloride on CH4 hydrate growth and agglomeration in oil-water systems

Abstract

Low dosage hydrate inhibitor (LDHI) is an effective choice to prevent hydrate formation and blockage in petroleum and natural gas processing industry. This study investigated the effect of dodecyl dimethyl benzyl ammonium chloride (DDBAC) on CH4 hydrate growth and agglomeration in oil-water systems. Hydrate formation kinetics and torque changes were determined with the isothermal-isochoric method. The kinetic experimental results revealed that 0.35 wt% DDBAC exerted a strong and stable inhibition effect on CH4 hydrate growth, represented by long induction time and low gas uptake amount. The chemical affinity modeling calculation results showed that DDBAC decreased normalized hydrate formation rate and increased the kinetic equilibrium time. The torque changes demonstrated that anti-agglomeration effect strengthened with the increase of DDBAC mass fraction. In addition, the mechanism of CH4 hydrate formation in studied system was proposed combining the experimental results, hydrate morphology and DDBAC’s properties. It showed that DDBAC could hinder gas dissolution in oil phase, separate hydrate particles from each other and make hydrate surface soft. These results are of fundamental value in developing LDHI and understanding the mechanism of hydrate formation, which are essential in preventing hydrate blockage and ensuring safety production of oil and gas.