contribute to offshore hydrate becoming economically viable because much of the technology required can be provided from that developed for conventional deep-water hydrocarbon exploration and production technology.

In addition, horizontal drilling has become a viable technique, and the "reach" of horizontal wells will continue to be extended. In many proposed production schemes for methane hydrate, horizontal wells (e.g. for heat injection) are a key element (e.g., Max and Lowrie, 1997). Without a doubt, the continuing advancements in both offshore operations and horizontal drilling will bring forward the commercial development of methane hydrate.

Recently, I have conducted a simplified "Delphi process" (Turoff and Hiltz, 1995) to obtain a judgement from some twelve leading experts working on methane hydrate production research across the globe, both in non-commercial institutes and in commercial enterprises. The question was as to when (if at all) the onset of commercial methane production from natural hydrate will most likely occur. Most experts distinguished between on-shore and offshore hydrate reservoirs, the former being considered as relatively easier targets, because of their generally higher formation permeabilities and hydrate saturations. In addition, the environment on land is less difficult operationally. On the other hand, markets are important and offshore occurrences are likely to be near markets (Japan, India, Canada). All in all, methane production from on-shore hydrate is likely to occur before offshore production.

The experts opinions spanned quite wide ranges, in part because judgements naturally differ, and possibly also because of different views on the implications of the terms "onset" and "commercial". From Fig. 3 it can be seen that the hydrate community on average expects commercial methane production from on-shore hydrate occurrences to begin before 2015. (This is consistent with the National Methane Hydrate Multi-Year R&D Program of the US Department of Energy, of which the ultimate goal is commercial methane production from hydrate by 2015.) However, commercial exploitation of offshore methane hydrate lies further into the future: the cumulative 50% probability point lies beyond 2060. It must be noted that at least 95% of the methane in hydrate deposits is to be found in continental slope sediments; the offshore represents the fundamental challenge and potentially the greatest reward.

Expert Opinion Commercials
Figure 3. Cumulative compilation of experts' opinions on when the onset of commercial gas production from hydrate will occur.

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