2025 Volume 141 Pages 115-124
Methane Hydrate (MH) has attracted international attention as an alternative energy resource to traditional fossil fuels. Research on production technology has been conducted in Japan to enable private companies to commercialize gas production from the MH in the seabed of Japan’s Exclusive Economic Zone. In this study, a numerical analysis is conducted to examine the multi-phase flow characteristics in a shallow-type MH production system by a gas-lift pump, and to predict the performance of practical production systems. The one-dimensional drift flux model is employed in the program. A numerical model for phase change is devised. Further, the flow characteristics of mud water are implemented in the analysis. The simulation results revealed that slurry flow rate increases as the flow rate of MH particles increases, and the volume fractions and the temperature along the lifting pipe are affected by phase change. The MH production rate: 6912t/d, volume concentration of MH particles: 16.8 – 12.5 %, slurry flux: 4.17 – 5.58 m/s, power requirement: 1240 – 2390 kW are predicted under the dimensions; length and water depth of lifting pipe: 940 and 900 m, water depth at gas injection point: 300 m, pipe diameter below and above gas injection point: 0.4 and 0.5 m, respectively and operational conditions; back pressure: 0.2 MPa(G), volume concentration of mud in slurry: 5%, gas flow rate: 4 – 8 kg/s. We demonstrated that the program could simulate the flow in the MH production system using a gas-lift pump well, and it could derive useful information and know-how in advance for designing and operating the system.
