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Title: Field observations, preliminary model analysis, and aquifer thermal efficiency

Journal Article · · United States Geological Survey, Professional Paper; (United States)
OSTI ID:7276924

In May 1980, the University of Minnesota began a project to evaluate the feasibility of storing heated (150 degrees Celsius ([degrees]C)) water in the deep (180 to 240 meters (m)) Franconia-Ironton-Galesville aquifer and later recovering it for space heating. The Aquifer Thermal-Energy Storage (ATES) system was a doublet-wall design in which the injection and withdrawal wells were spaced approximately 250 m apart. High-temperature water from the university's steam-generation facilities supplied heat for injection. Water was pumped from one of the wells through a heat exchanger, where heat was added or removed. Water then was injected back into the aquifer through the other well. The experimental plan for testing the ATES system consisted of a series of short-term hot-water injection, storage, and withdrawal cycles, Each cycle was 24 days long, and each injection, storage, and withdrawal step of the cycle was 8 days. The effects of various injection and withdrawal rates and durations on computed values of aquifer relative-thermal efficiency and final well-bore temperature were studied for five 1-year hypothetical test cycles of injection and withdrawal. The least efficient scheme was 8 months injection of 150[degrees]C water at 18.9 L/s and 4 months of withdrawal of hot water at 18.9 L/s. The most efficient scheme was obtained with 6 months of injection of 150[degrees]C water at 18.9 L/s and 6 months of withdrawal of hot water at 37.8 L/s. The hypothetical simulations indicate that the calibrated model of the doublet-well system would be a valuable tool for use by the university in selecting a highly efficient system operation. In the second model, analytical solutions of anisotropic hydraulic flow around the doublet-well system were obtained to provide fluid-flux boundary conditions around the heat-injection well in three dimensions.

OSTI ID:
7276924
Journal Information:
United States Geological Survey, Professional Paper; (United States), Vol. 1530-A
Country of Publication:
United States
Language:
English