Study on the Multiphase Flow Behavior in the Jet Pump Lifted Natural Gas Hydrate Wells with Combined Depressurization and Heat Injection Method

Abstract Natural gas hydrate production tests have been carried out successfully with different exploitation methods and gas recovery drainage technologies. The purpose of this study is to elucidate the fluid flow behavior in the jet pump lifted natural gas hydrate wells and optimize hot water injection parameters for the jet pump drainage gas recovery technology. The mechanism of jet pump drainage recovery of natural gas hydrate wells was analyzed and its applicability to natural gas hydrate exploitation with combined depressurization and heat injection method was demonstrated. In addition, multiphase flow models of tubing and annulus were established respectively for the phenomenon of countercurrent flow of heat exchange in the jet pump drainage gas recovery process, and the corresponding multiphase flow laws were derived. Based on the study of multiphase flow, sensitivity analysis and optimization of heat injection parameters were performed. It has been demonstrated that jet pump drainage gas recovery technology is suitable for the exploitation of onshore natural gas hydrate with combined depressurization and heat injection method. The multihphase flow behavior in the tubing and annulus of the jet pump lifted natural gas hydrate wells was disclosed in this study. Numerical simulation results show that the temperature and pressure distribution in the wellbore of the jet pump lifted natural gas hydrate wells during the recovery process are affected by the injection conditions. This study provides theoretical guidance for the production optimization and hydrate prevention and control in the wellbore of the jet pump lifted natural gas hydrate wells.