35,000 trillion cubic feet — and rising

The numbers are jaw-dropping, but don’t count on anything definitive if you’re looking for an accurate guide to the world’s unconventional gas resources. Just accept that the potential is often beyond comprehension.

Velio Kuuskraa, a Washington, D.C.-based consultant, believes the 35,000 trillion cubic feet estimate of global resources produced by German energy economist Hans-Holger Rogner is a reasonable guess.

And he bases that on 30 years of work in the field, including his current role as president of Advanced Resources International.

Kuuskraa said that regardless of the wide discrepancies in putting numbers on unconventional gas, the economic future of the resource is beyond debate.

What’s more he told a Calgary conference in the fall that the numbers keep rising as technical skills advance.

But the imprecise nature of the calculations is reflected in the wide range of U.S. estimates for technically recoverable unconventional gas. Anadarko Petroleum assigns a number of 700 tcf, Advanced Resources International 511 tcf, the U.S. Geological Survey 325 tcf, and the National Petroleum Council 268 tcf.

The USGS recently estimated 3.1 tcf of gas can be recovered from the Williams Fork tight formation in Colorado’s Piceance Basin; Kuuskraa puts the figure at 31.3 tcf, based on tighter well spacing and a higher percentage recovery.

Rogner said North America has the greatest unconventional gas resources in place, trailed by the former Soviet Union and China.

Mike Gatens, chief executive officer of coalbed methane producer MGV Energy, said that regardless of the source “we need (Arctic) gas; we need unconventional gas; we need new, innovative ways to increase our recovery efficiencies. We need all of it.”

—Gary Park