Canadian Arctic Region. Courtesy of Tom Mroz, National Energy Technology Laboratory.

R&D on the production potential of methane hydrates will focus on two issues: (1) the necessary characteristics of a hydrate accumulation that will allow feasible production; and (2) production strategies that will be most effective in allowing safe, cost-effective recovery. No one doubts that the conversion of natural methane hydrates into a viable resource will pose enormous technical challenges.

The published estimates of the size of the methane hydrate resource are staggeringly large. However, it is clear that much of that resource is not likely to ever be converted to a reserve—gas that can be obtained economically. Initial research on hydrate production strategies will likely focus on the relatively less challenging permafrost accumulations. Although only a small fraction of the hydrate resource lies on land, the accessibility of these deposits provides an effective means to test how hydrates respond to various production methods. Nonetheless, the most obvious difficulty facing the large-scale economic production of methane from hydrates is that the vast bulk of the resource occurs as diffuse and widespread deposits located beneath deep waters. Just as is the case with conventional oil and gas resources, economic recovery will certainly require the identification of select areas (“sweet-spots”) of unusually high hydrate concentration. Advanced seismic and other remote-imaging technologies will be needed to provide this prospect delineation.

A second challenge will be posed by the nature of the enclosing sediment. Much of the world’s hydrate resource exists on deep-water continental shelves. These areas are generally characterized by very fine-grained, unconsolidated, and homogeneous sediment. Although such sediment can hold large amounts of water and methane, it typically lacks the permeability necessary to allow gas and fluid to flow—a property necessary to allow extraction by conventional well drilling. On land, low permeability formations can be treated to create artificial permeability through fracture stimulation. Such practice is not likely to work in soft, deformable, mud. Consequently, the best prospects for hydrate production will come, at least initially, from those tectonically-active continental shelves (such as Japan’s Nankai Trough or North America’s Cascadia Margin) that are characterized by heterogeneous and more coarsly-grained sediments.

Despite these difficulties, the reserve potential of methane hydrates remains enormous— the reason is the sheer volume of the resource. In order to estimate the amount of methane that hydrate deposits may be capable of contributing to supply, one must estimate the likely percentage of the in-place hydrate resource that can be expected to be economically recoverable given likely advances in technology. For example, consider that the U.S. domestic natural gas recoverable resource of roughly 2,300 trillion cubic feet (Tcf , with 1,400 Tcf remaining and 900 Tcf produced), is derived from an "in-place" resource that could easily range upwards from 25,000 Tcf if ever quantified (we know, for example, that the Cretaceous units in the Greater Green River basin of Wyoming alone contain as much as 5,000 Tcf of in-place gas). In the case of methane hydrates, if several large “sweet spots” can be located, the potentially-recoverable domestic hydrate resource base could be on the order of 5,000 Tcf (2.5% of the 200,000 Tcf total estimated to exist in the US Exclusive Economic Zone). Further, assuming technologies can be developed that will allow recovery at even half the rate obtainable in “conventional” reservoirs, the ultimate recoverable hydrate resource could range from 1,500 to 2,000 Tcf. The allure of hydrates is that this volume, which may be less than 1% of the total in-place hydrates resource, would still more than double the nation’s current estimated remaining recoverable domestic resource from all discovered and undiscovered natural gas reservoirs.