The techniques in geothermal resource assessment are summarized, terminology and assumptions are clarified, and a foundation for the development of optimum geothermal resource assessment methodology is provided. A logical, sequential subdivision of the geothermal resource base is proposed, accepting its definition as all the heat in the earth's crust under a given area, measured from mean annual temperature. That part of the resource base which is shallow enough to be tapped by production drilling is termed the accessible resource base, and it in turn is divided into useful and residual components. The useful component (i.e., the heat that could reasonably …
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Geological Survey, Denver, CO (USA)
Place of Publication:
Denver, Colorado
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The techniques in geothermal resource assessment are summarized, terminology and assumptions are clarified, and a foundation for the development of optimum geothermal resource assessment methodology is provided. A logical, sequential subdivision of the geothermal resource base is proposed, accepting its definition as all the heat in the earth's crust under a given area, measured from mean annual temperature. That part of the resource base which is shallow enough to be tapped by production drilling is termed the accessible resource base, and it in turn is divided into useful and residual components. The useful component (i.e., the heat that could reasonably be extracted at costs competitive with other forms of energy at some specified future time) is termed the geothermal resource. This in turn is divided into economic and subeconomic components, based on conditions existing at the time of assessment. In the format of a McKelvey diagram, this logic defines the vertical axis (degree of economic feasibility). The horizontal axis (degree of geologic assurance) contains identified and undiscovered components. Reserve is then designated as the identified economic resource. All categories should be expressed in units of heat, with resource and reserve figures calculated at wellhead, prior to the inevitable large losses inherent in any practical thermal use or in conversion to electricity. Methods for assessing geothermal resources can be grouped into 4 classes: (a) surface thermal flux, (b) volume, (c) planar fracture, and (d) magmatic heat budget. The volume method appears to be most useful.
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Muffler, P. & Cataldi, R.Methods for regional assessment of geothermal resources,
report,
January 1, 1977;
Denver, Colorado.
(https://digital.library.unt.edu/ark:/67531/metadc1208202/:
accessed May 13, 2025),
University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu;
crediting UNT Libraries Government Documents Department.
