U.S. Natural Gas Resources Increased Significantly
According to the press-release form the The Potential Gas Committee, which receives guidance from the Potential Gas Agency at the Colorado School of Mines, the United States possess a total technically recoverable resource base of 2,384 trillion cubic feet (Tcf) as of year-end 2012. This is the highest resource evaluation in the Committee’s 48-year history, exceeding the previous high assessment (from 2010) by 486 Tcf. Most of the increase arose from new evaluations of shale gas resources in the Atlantic, Rocky Mountain and Gulf Coast areas.
These changes have been assessed in addition to 49 Tcf of domestic marketed-gas production estimated for the two-year period since the Committee’s previous assessment.
“The PGC’s year-end 2012 assessment reaffirms the Committee’s conviction that abundant, recoverable natural gas resources exist within our borders, both onshore and offshore, and in all types of reservoirs—from conventional, ‘tight’ and shales, to coals,” said Dr. John B. Curtis, Professor of Geology and Geological Engineering at the Colorado School of Mines and Director of the Potential Gas Agency there, which provides guidance and technical assistance to the Potential Gas Committee.
Dr. Curtis cautioned, however, that the current assessment assumes neither a time schedule nor a specific market price for the discovery and production of future gas supply. “Assessments of the Potential Gas Committee represent our best understanding of the geological endowment of the technically recoverable natural gas resource of the United States,” he explained.
The Committee’s year-end 2012 assessment of 2,384 Tcf includes 2,226 Tcf of gas potentially recoverable from “Traditional” reservoirs (conventional, tight sands and carbonates, and shales) and 158 Tcf in coalbed reservoirs. Compared to year-end 2010, assessed Traditional resources increased by 486.4 Tcf (28%), while coalbed gas resources declined by a nominal 0.4 Tcf (0.2%), resulting in a net increase in total potential resources of 486.1 Tcf (25.6%). (See accompanying Table 1.)
When the PGC’s assessments of technically recoverable resources are combined with the U.S. Department of Energy’s latest available determination of proved reserves, 305 Tcf (dry gas) as of year-end 2010, the United States has a total available Future Supply of 2,688 Tcf, an increase of 486 Tcf over the previous evaluation. While the PGC reports these assessments of potential resources and future supply summarily on the national level, the Committee believes that the individual province-level assessment results offer the greatest value for purposes of analysis, planning and exploration.
As Dr. Curtis observed, “Our knowledge of the geological endowment of technically recoverable gas continues to improve with each assessment. Furthermore, new and advanced exploration, well drilling, completion and stimulation technologies are allowing us increasingly better delineation of and access to domestic gas resources—especially ‘unconventional’ gas—which, not all that long ago, were considered impractical or uneconomical to pursue.”
“Consequently, our present assessment, strengthened by robust domestic production levels, demonstrates an exceptionally strong and optimistic gas supply picture for the nation.”
As a result of a substantial increase in the assessment of Appalachian basin shale gas, the PGC now ranks the Atlantic area as the country’s richest resource area with 33% of total U.S. Traditional resources, followed by the Gulf Coast (including the Gulf of Mexico) and Rocky Mountain areas, which together account for 76% of the assessed total Traditional resource. (See accompanying Table 2.) Changes in the total assessment from 2010 to 2012 arose primarily from analyses of recent drilling, well-test and production data from these three regions. The largest volumetric and percentage gains were reported for Appalachian basin shales (primarily the Marcellus but including other Devonian shales and the Utica), which collectively rose by 335 Tcf (147%). A substantial increase, 21.6 Tcf (58%), also was made for the Eagle Ford Shale in the Texas Gulf Coast basin. Cretaceous shales in the Rocky Mountain area figured prominently in new record-high assessments for the Greater Green River basin (Baxter and Hilliard Shales) and San Juan basin (Mancos and Lewis Shales), in each case more than double the province’s total potential gas assessment for 2010. Reevaluation of another unconventional resource, the Niobrara Formation, led to a new record assessment of 7.5 Tcf for the Denver basin, a jump of nearly 3.5 Tcf (86%).
The growing importance of shale gas is substantiated by the fact that the PGC’s total assessed shale gas resource of 1,073 Tcf for 2012 accounts for approximately 48% of the country’s total Traditional potential resources.
