Study of subsea type gas production system for methane hydrate under the seabed by gas-liquid two-phase flow model

Japan imports more than 94% of its primary energy supply and the import figures reach up to 250 billon US dollars every year. Imported energy resources in the form of crude oil and natural gas are mainly from Middle East Asia and South Asia. The political instability in these region and crude oil scarcity in the future possess a risk of procurement for the energy demands. Improvement of rate of energy self-sufficiency and diversification of supply sources are then become an urgent issue in Japan. In recent years, rich reserves of methane hydrate were discovered in the Sea of Japan, and it is expected that reserves can cover energy consumed amount in Japan for 100 years. In this study, we examine a subsea type gas production system for methane hydrate under the seabed. The design of subsea type device for methane hydrate production was investigated in order to grasp the pressure distribution and void fraction distribution of the wellbore and numerical simulation was performed for gas-liquid two-phase flow, bottom-hole pressure, the initial flow rate, pipe diameter.