Multiphase flow computational model for extraction of gas hydrates in marine soft soils

The gas hydrate is a type of unconventional clean energy with substantial reserves. The successful and safely extraction of gas hydrates is of great significance in guaranteeing the energy safety of China. At present the depressurization method is a kind of the most widely used and promising extraction means for the gas hydrates. The problems of multiphase flow in the reservoir caused by hydrate phase transition are studied theoretically and numerically. Firstly, a mathematical model for coupling the kinetic decomposition of the gas hydrates and the multiphase flow in porous media is established. The proposed model is numerically implemented by the software COMSOL Multiphysics, and its effectiveness is validated through the Masuda's experiments. Then, the sensitivity analysis for the key factors which have impact on the extraction of the gas hydrates is conducted. The results show that the gas production rate increases with the increase of the permeability and pressure drop amplitude.