Characteristics of Methane Hydrate Formation in a Gas–Water–Silt Sand Three-Phase Flow System and Its Effect on Multiphase Flow Behavior

In this work, methane hydrate formation experiments are conducted under the methane gas–water–silt sand three-phase flow by using a novel flow loop. The experimental results show that the increase in flow velocities and silt sand concentrations both increase the methane hydrate formation rate and the pressure drop of the three-phase fluid. The flow velocity has a stronger effect on hydrate formation rates and pressure drops than the silt sand concentration, but under the same flow velocity condition, the increase in silt sand concentrations amplifies the effect of flow velocity. Moreover, a new interesting observation is found that, during the methane hydrate formation, the pressure drop of the mixture fluid exhibits a nonlinear relationship with experiment time, which has a similar trend to the methane hydrate formation rate vs experiment time. The phenomenon of methane hydrate formation can influence the pressure drop significantly, in that the increase in the hydrate formation rate results in the larger pressure drop. This work provides a theoretical foundation for developing the hydrate management plan for the water-drainage pipe line in a natural gas hydrate production well.