Correction to “Aquifer Thermal Energy Storage: A Well Doublet Experiment at Increased Temperatures” by F. J. Molz, J. G. Melville, A. D. Parr, D. A. King, and M. T. Hopf

Abstract

In the paper Aquifer thermal energy storage: A well doublet experiment at increased temperature by F. J. Molz et al. (Water Resources Research, 19(1), 149-160, 1983), an erroneous coefficient was inadvertantly used. This came about as follows: During the aquifer thermal energy storage (ATES) experiments conducted by Auburn University at a field site near Mobile, Alabama, relative land elevation changes were recorded between points near the injectionproduction well and two benchmarks located beyond the thermal radius of influence [Molz et al., 1981, 1983a]. Based on a brief calculation presented by Molz et al. [1981], it was concluded that most of the elevation increase near the injection well (a maximum of 1.39 cm) was due to thermal expansion of low-permeability, water-saturated clays. Thermal expansion of the aquifer matrix did not appear adequate to cause the observed land surface elevation change. Unfortunately, the conclusion that aquifer matrix expansion did not contribute significantly to the observed land elevation increase was based on an erroneous coefficient of thermal expansion. A value appropriate for fused quartz (--•5.5 x 10 -7 oC-•) was used when a value for crystalline quartz (--•1.2 x 10 -5 oC -!) was intended [Skinner, 1966]. Needless to say, an error by a factor of 22 in a key parameter changes one's view of the world, so it now appears that simple thermal expansion and contraction of the aquifer matrix played a major role in causing the land elevation changes at the Mobile site. One important implication of this is that the potential for land elevation variations associated with ATES is greater than supposed previously [Molz et al., 1983a, b]. P.resently, a detailed theoretical and experimental study of the elevation change mechanism is underway. In the near future we hope to have a more quantitative xplanation for the observed elevation changes.