From Bureau of Economic Geology, The
University of Texas at Austin (www.beg.utexas.edu).
For more information, please contact the author.
Bureau Seminar, October 21, 2011
The Transformation of Hydrofrac-ed Reservoirs to Thermal Energy Production
Link to streaming video: available 10.21.2011 at 8:55am
Bruce L. Cutright
Bureau of Economic Geology, UT Austin
Organic rich low permeability formations in many locations throughout North America contain significant volumes of natural gas, but not until the early 1990s was it deemed practical to extract this gas resource in economic quantities. Hydrofracturing, pioneered by Mitchell Energy Company on the Barnett Shale in East Texas demonstrated the technical feasibility of developing these tight formations along with horizontal drilling techniques that resulted in high-volume yields from wells that previously did not flow at rates sufficient to recover the initial investment of drilling. Development of these tight formations using hydrofracturing and horizontal drilling has transformed the North American natural gas industry, and has added, by some estimates, at least another 200 years of reserves at the present rate of natural gas consumption. Individual wells, however, in most circumstances, do not have an extended economic lifetime as yields from these fracture-stimulated wells generally decline quickly and new wells must be drilled and fractured. The substantial investment in well design, installation and reservoir stimulation should not be abandon, however, as many of these wells can be converted into thermal mining wells, yielding geothermal energy on a sustainable basis for an extended period of time. Parametric analysis of typical wells indicates that each well cluster contains and can yield in thermal energy from ten million to eighty million barrels of oil equivalent in extractable thermal energy, and there are several thousand promising candidate wells for this procedure. As important as is demonstrating the extractable thermal energy from these wells is that these thermal yields are renewable over reasonable time frames making the potential energy production from these wells in geothermal energy as significant as the natural gas originally produced from the wells.