The Effects of a Step Change in Water Flow on an Initially Linear Profile of Temperature
In recent analyses of the hot-water system at Wairakei, New Zealand (Mercer, Pinder, and Donaldson, 1975) and the vapor-dominated system at Larderello, Italy (Petracco and Squarci, 1975), it has been suggested that large quantities of cold water are entering the reservoir by flowing down from the surface and then horizontally into the reservoir because of decreased reservoir pressures. It is also suggested that decreased reservoir pressures should increase these downward flows above their pre-exploitation levels. In order to estimate the effects of vertical flows on the temperature distribution, two idealized problems are analyzed in this paper. In both problems, the initial condition is a linear temperature increase with depth, and the flow starts at time equal to zero. In the first problem, the flow is through a semi-confining layer with the temperature fixed at the top and bottom of the layer. In the second problem, the flow is into a half-space with the surface temperature fixed. The magnitudes of the effects for the two cases considered suggest that monitoring temperatures in undisturbed wells on the margins of producing geothermal areas should give a measure of the change in the fairly local recharge. If the amount of total recharge is known, subtracting the localized recharge should give an estimate of the recharge derived from deep circulation that originates at large distances from the reservoir. 7 refs., 2 figs.
- Research Organization:
- U.S. Geological Survey, Menlo Park, CA
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 887309
- Report Number(s):
- SGP-TR-20-8
- Country of Publication:
- United States
- Language:
- English
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