Anisotropy in the Ironton and Galesville Sandstones Near a Thermal‐Energy‐Storage Well, St. Paul, Minnesota

Abstract

The U.S. Geological Survey is studying the potential for storage of heated water in a sandstone aquifer in St. Paul, Minnesota. The efficiency of the aquifer to store thermal energy is related, in part, to the hydrogeologic characteristics of the aquifer. The movement of heat away from the injection well is directly related to the anisotropy. Aquifer tests were conducted to determine the anisotropy near the heated‐water injection well. The maximum and minimum values of transmissivity along the principal directions of the hydraulic conductivity tensors of the Ironton and Galesville Sandstones in St. Paul, Minnesota are approximately 1,090 and 480 feet squared per day. The storage coefficient is 4.5 × 10−5. These values represent the average of four determinations of nonsteady flow to a well in an idealized infinite anisotropic aquifer. Analysis of the values of transmissivity and storage coefficient for hypothetical changes in location of two of the monitoring wells where depth‐deviation surveys were not available indicates that computed transmissivities vary less than 5 percent and storage coefficients vary less than ±6 percent.

Ground-water recharge and flowpaths near the edge of the Decorah-Platteville-Glenwood confining unit, Rochester, Minnesota

“…Packer-test data in the St. Paul area reported by Miller (1984) indicated a vertical hydraulic conductivity of 10 -3 ft/d for the St. Lawrence confining unit,whereas a value of 10 -5 ft/d was estimated from numerical groundwater-flow model analysis for the Minneapolis-St. Paul metropolitan area (Schoenberg, 1990). Freeze and Cherry (1979) indicate a range in porosity of from less than 20 to less than 5 percent for shale.…”

University of Minnesota aquifer thermal energy storage (ATES) project report on the third long-term cycle

“…The USGS responsibility was simulation of the injection, storage and retrieval of heated water in the aquifer (Miller 1984(Miller , 1985(Miller , 1986Miller and Delin 1993;Miller and Voss 1986). Simulation results and methodology also were used for comparison with the geochemical and system simulation work underway at PNL (Vail 1989).…”

Ground-water contamination by crude oil at the Bemidji, Minnesota, research site; US Geological Survey Toxic Waste--ground-water contamination study

“…A method described by Papadppulos (1965) and applied by Miller (1984) for nonsteady flow to a well in an infinite anisotropic aquifer will be used to determine principal values of horizontal hydraulic conductivity. Because the aquifer at the Bemidji site is unconfined, tests must be sufficiently long to assure horizontal flow at observation wells (E. P. Weeks, oral commun., U.S. Geological Survey, Denver, Colo.) , and to minimize effects of lateral boundaries on the flow field.…”