It is noted that natural gas hydrate exists in geological formations and constitutes a potentially large natural gas resource for the future. To make recovery of natural gas from hydrates commercially viable, hydrates must be dissociated in-situ. At the present stage, depressurization method is expected to be a main dissociation procedure because of its high energy profit ratio and so on. Whereas, there is a worry that some interruptions for gas production i.e. plugging by hydrate formation will occur. Also there is a demand to enhance the recovery ratio of natural gas. In this study, inhibitor injection with higher methanol concentration has been examined using laboratory made methane hydrate bearing sediment. As a result, it becomes clear that the higher concentration effectively contribute to the faster gas production rate. Whereas, dilution of methanol by pure water from hydrate dissociation were observed significantly, compared to the case of lower concentration.
Natural gas hydrates are crystalline compounds that can contain a large amount of natural gas (Sloan, 1998). Owing to recent seismic exploration and geological research, it is widely known that natural gas hydrate that exists in the sediment constitutes a large natural gas resource and is expected to be an energy source in the future (Makogon, 1981; Brooks et al., 1986; Kvenvolden, 1988; Kvenvolden et al., 1993; Okuda, 1993; Gornitz and Fung, 1994; Sassen, 2001). To make recovery of natural gas from hydrates commercially viable, hydrates must be dissociated in-situ. At the present stage, depressurization method is expected to be a main dissociation procedure because of its high energy profit ratio and so on. Whereas, there is a worry that some interruptions for gas production i.e. plugging by hydrate formation will occur. Also there is a demand to enhance the recovery ratio of natural gas.
