Numerical simulation of natural gas hydrate development with radial horizontal wells based on thermo-hydro-chemistry coupling

This paper investigates the efficiency of natural gas hydrate (NGH) production by radial horizontal wells. The multi-field coupling model is developed to describe the phase change, two-phase porous seepage flow, and the heat and mass transfer in the NGH production process, which is verified to be reliable by Masuda's core-scale experiment. Using this coupling method, the NGH production process by radial horizontal wells is simulated. The results indicate that: (i) The hydrate dissociation by radial horizontal wells occurs in a larger range and higher degree than the conventional vertical well. (ii) The pore pressure drop along the horizontal plane of radial lateral holes is more significant than that of the vertical plane. (iii) The increases of the length and/or the diameter of the radial horizontal wells can increase the gas production rate obviously. (iv) There is unfavorable interact for hydrate dissociation between adjacent branches when the branch number is equal to or larger than four. The radial horizontal wells with three branches should be the optimal. This study provides suggestions and theoretical reference for application of radial horizontal well in the development of NGH reservoirs.