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FROZEN HEAT
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For many years, gas hydrate resources were characterized by
extremely large numbers, with perhaps the most commonly-
cited value being 700 000 trillion cubic feet (roughly 20 000
trillion cubic metres). While such numbers are meaningful
in the context of understanding the role of gas hydrates in
carbon cycling and other global processes, they tended to
significantly overstate the practical resource potential of
gas hydrates by lumping together all manner of gas hydrate
occurrences (Boswell and Collett 2011). Earlier attempts
to dissect resources of all kinds according to potential
productivity revealed a characteristic pyramid shape, with
the most favourable elements (at the top) occurring in
relatively small volumes, while those resources that pose
greater technical challenges (at the bottom) commonly
occur in far greater abundance (Masters 1979: Kuuskraa and
Schmoker 1998). A pyramid devised for the specific case of
gas hydrates (Figure TB2.1.1; after Boswell and Collett 2006)
is no different.
As with all resource pyramids, the gas hydrate pyramid only
suggests the overall order in which production is expected
to occur, with resources at the top of the pyramid likely to
Box 2.1
The gas hydrate resource pyramid
be produced before those at the bottom. At present, the global
energy industry has worked its way well down the total gas
resource pyramid, having focused on shallow onshore deposits at
the onset and beginning only recently – after more than a century
of exploration – to seriously exploit larger elements at the base,
such as shale gas. A similar progression can be expected for gas
hydrates. However, the time intervals could well be shorter, given
increasingly strong global demand for energy and, in particular,
growing use of the relatively carbon-efficient natural gas.
While gas hydrate in-place resources change – and change
dramatically – over geologic time (see Volume 1 Chapter 2), it
is safe to assume that the in-place gas hydrate resource is, for
practical purposes, unchanging over human time scales. However,
the ability to work through the resource pyramid means that
resource recoverability is time-dependant, and the general nature
of technological advance (which can be intermittently evolutionary
and revolutionary) suggests that recoverable volumes can change
dramatically and quickly. In addition, simply being recoverable
does not mean a resource will be utilized. It must also be viable
economically, which introduces a range of complex and locally
varying economic, political, and societal factors.
Figure TB-2.1:
The total in-place natural gas resources represented globally by methane hydrates are enormous, but they occur in a
wide range of accumulation types. As with other petroleum resources, the accumulation types most favorable for production are the
least abundant, creating a pyramidal resource distribution. A generalized resource pyramid for gas hydrates (right) is shown in relation
to resource pyramid for all gas resources (left). Society continues to progress down through the global gas pyramid (left), aided by
occasional technological breakthroughs that enable significant access to previously unrecoverable resources. Gas hydrates (right)
may experience a similar progression with initial production most likely to occur within marine or Arctic sands. Given the vast scale of
hydrate resources, however, potential volumes even at the apex of the hydrate pyramid are significant. Figure after Boswell and Collett,
2006. “The Gas Hydrates Resource Pyramid.”