World estimates of the amount
of methane sequestered in gas hydrates are enormous, but published estimates
are highly speculative. It is generally believed, however, the amount
of gas in the hydrate reservoirs of the world greatly exceeds the volume
of known conventional gas reserves. Until recently, relatively little
work has been done to assess the availability and production potential
of gas hydrates. Gas recovery from hydrates is hindered because hydrates
occur as a solid in nature and are commonly widely dispersed in hostile
Arctic and deep marine environments. Proposed methods of gas recovery
from hydrates usually deal with dissociating in-situ gas hydrates by heating
and/or depressurizing the reservoir. Among the various techniques for
production of natural gas from in-situ gas hydrates, the most economically
promising method is considered to be the depressurization scheme.
Despite the fact that relatively
little is known about the ultimate resource potential of natural gas hydrates,
it is certain that gas hydrates are a vast storehouse of natural gas and
the national gas hydrate research programs of Japan, India, and the United
States will significantly contribute to our understanding of the technical
challenges needed to turn this enormous resource into a economically producible
reserve.
In conclusion, will gas hydrates
become a significant energy resource? It is unlikely that we will see
significant worldwide gas production from hydrates for the next 30 to
50 years. However, in certain parts of the world characterized by unique
economic and/or political motivations, gas hydrates may become a critical
sustainable source of natural gas within the foreseeable future, possibly
in the next five to ten years.