The discovery of large gas
hydrate accumulations in terrestrial permafrost regions of the Arctic
and beneath the sea along the outer continental margins of the world's
oceans has heightened interest in gas hydrates as a possible energy
resource. However, significant to potentially insurmountable technical
issues need to be resolved before gas hydrates can be considered a viable
option for affordable supplies of natural gas.
Disagreements over fundamental
issues such as volume of gas stored within delineated gas hydrate accumulations
and the concentration of gas hydrates within hydrate-bearing reservoirs
have demonstrated that we know very little about gas hydrates. Recently,
however, several countries, including Japan, India, and the United States,
have launched ambitious national projects to further examine the resource
potential of gas hydrates. These projects may help answer key questions
dealing with the properties of gas hydrate reservoirs, the design of
production systems, and, most importantly, the costs and economics of
gas hydrate production.
It is proposed in this paper
that the evolution of gas hydrates as a viable source of natural gas,
like any other unconventional energy resource (e.g., deep gas, shale
gas, tight gas sands, and coalbed methane), will follow a predictable
path from research and discovery to implementation (Figure 1); however,
insurmountable barriers may exist along this pathway.
Today, most of the gas hydrate
research community is focused on three fundamental issues: WHERE do
gas hydrates occur, HOW do gas hydrates occur in nature, and WHY do
gas hydrates occur in a particular setting. However, relatively little
has been done to integrate these distinct research topics or evaluate
how collectively they affect the ultimate resource potential of gas
hydrates. Only after understanding the fundamental aspects of WHERE-HOW-WHY
gas hydrates occur in nature will we be able to make accurate estimates
of how much gas is trapped within the gas hydrate accumulations of the
world. Even with the confirmation that gas hydrates may exist in considerable
volumes, significant technical, economic, and political issues need
to be resolved before gas hydrates can be considered a viable energy
resource.
In this paper, I have attempted
to review the status of gas hydrates as a future energy resource. The
technical and non-technical factors controlling the ultimate resource
potential of gas hydrates have been identified and assessed. The fundamental
questions of WHERE do gas hydrates occur, HOW do gas hydrates occur
in nature, and WHY do gas hydrates occur in a particular setting have
been individually reviewed and discussed. In addition, published gas
hydrate volume assessments have been summarized and the production technology
needed to extract the world’s gas hydrate resources are assessed. The
paper concludes with a discussion of the economic and political motivations
that may eventually lead to gas hydrate production. However, before
proceeding with the assessment of the future energy resource potential
of gas hydrates, this paper begins with a technical overview of gas
hydrate physical properties and a review of four relatively well characterized
gas hydrate accumulations.