211-6 Geothermal Energy Extraction and Thermal Springs

Session: Geothermal Resources Research

Presenting Author:

Authors:

Abstract:

High potential geothermal energy sites occur where geothermal gradients are high and heat from the subsurface can be extracted for use on the earth’s surface. In many geothermal areas, water carries heat to the surface through faults to form thermal springs. Whether larger scale geothermal development will lead to cooling of the thermal springs or reduction in spring discharge rate is unclear.

This study models groundwater flow and heat transport using the USGS software SUTRA to evaluate the potential impact of geothermal energy production on thermal springs. The modeled system is loosely based on the geologic and thermal setting near Mt. Princeton in central Colorado, USA. The model domain is three-dimensional, extending 11.5 km in east-west, 2 km in north-south, and 3 km in vertical directions. Mt. Princeton and the Mosquito Range bound the domain on the west and east, respectively, and a river runs from north to south along a narrow topographic low. The subsurface contains a sedimentary section overlying a crystalline basement with a fault zone separating a batholith to the west. The fault zone emanates warm water from subsurface to create a thermal spring at the surface. The fault zone was modeled as a narrow vertical unit with two sections: an upper fault zone in the sedimentary section and a lower fault zone in the basement. The base of the fault is modeled as a fluid source, and the top of the fault is a surface spring.

Simulation results demonstrate that for a prescribed set of hydrogeologic and geothermal conditions, warm-water extraction and cool-water injection for geothermal energy production can reduce the temperature of the thermal spring discharge. However, the modeled spring discharge rate is less sensitive to geothermal extraction. An implication of the modeling result is that the extraction of deep thermal water for geothermal energy production and the simultaneous injection of cooled water has the potential to reduce the water temperature of thermal springs. We acknowledge that all geothermal sites are unique with a varying degree of complexity in geology, hydrogeology, and thermal conditions. The results of the model developed for this study should not take the place of developing a detailed site-specific groundwater flow and heat transport model for a proposed geothermal energy production facility.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7044

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