Rock Characterization At a Geothermal Site.
Proc 17th Symp on Rock Mech Snowbird Utah 1976 Aug; :5D5-1--5d5-6
Several geophysical logs were run in a 3-kilometer borehole, that had been drilled for the purpose of extracting heat from a hot-dry granitic formation. Rock characterization tests were performed, both in the laboratory and field, to assist in the design of the hydrofracturing experiment and in improving drilling technology. Most of the properties determined from interpretation of the in situ geophysical measurements showed reasonably good agreement with the ones obtained under similar laboratory conditions. The minor discrepancies can be explained either by the presence of small open cracks in the rock core that may have been absent or closed in the rock mass, or by differences in the moisture environment. Greater discrepancies encountered in determining the porosity of the rock formation were due to the inapplicability of empirical formulas derived from experience gained in testing soft porous rock masses.
Proc. 17th Symp. on Rock Mech., Snowbird, Utah, Aug. 25-27, 1976, PP. 5D5-1--5d5-6