[...] But what is that estimate based upon? Those details haven’t been made freely available to the public, but their summary breaks it down as follows here and in the graph below: 273 tcf are "proved reserves," meaning that it is believed to exist, and to be commercially producible at a 10 percent discount rate. n additional 536.6 tcf are classified as "probable" from existing fields, meaning that they have some expectation that the gas exists in known formations, but it has not been proven to exist and is not certain to be technically recoverable. An additional 687.7 tcf is "possible" from new fields, meaning that the gas might exist in new fields that have not yet been discovered. A further 518.3 tcf are "speculative," which means exactly that. A final 176 tcf are claimed for coalbed gas, which is gas trapped in coal formations.Excellent article throughout. The "100 years of natural gas" meme is so common nowadays, it's just got to be centrally controlled propaganda. The motivation to exaggerate the reserves to attract investment is intense.
By the same logic, you can claim to be a multibillionaire, including all your "probable, possible, and speculative resources."
Assuming that the United States continues to use about 24 tcf per annum, then, only an 11-year supply of natural gas is certain. The other 89 years' worth has not yet been shown to exist or to be recoverable.
Even that comparably modest estimate of 11 years’ supply may be optimistic. Those 273 tcf are located in reserves that are undrilled, but are adjacent to drilled tracts where gas has been produced. Due to large lateral differences in the geology of shale plays, production can vary considerably from adjacent wells.
After mathematically modeling the actual production of thousands of wells in the Barnett, Fayetteville, and Haynesville Shales, Berman found that operators had significantly exaggerated their claims. Reserves appear to be overstated by more than 100 percent. Typically, the core 10 to 15 percent of a shale formation’s gas is commercially viable. The rest may or may not be—we don’t know at this point. Yet the industry has calculated the potentially recoverable gas as if 100 percent of the plays were equally productive.
We don't yet know how much of the estimated gas resources will be economically recoverable or whether the projected production rates for some wells might be off by a factor of 10. We might have a 100-year supply of gas, or we might have an 11-year supply. We might realize economic and environmental benefits by transitioning trucking and coal-fired power generation to natural gas, or we might do so only to find ourselves out on a limb far more economically dangerous than the current peak and impending decline of world oil supply. We simply don't know, and we may not know for years to come.
Friday, December 30, 2011
Fracking: Is there really 100 years’ worth of natural gas beneath the United States? Slate Magazine