Over the past 35 years the Buckman wellfield near Santa Fe, New Mexico, experienced production well drawdowns in excess of 180 m, resulting in ground subsidence and surface cracks. Increased reliance on surface water diversions since 2011 has reduced pumping and yielded water level recovery. To characterize the impact of wellfield management decisions on the aquifer system, we reconstruct the surface deformation history through the European Remote Sensing Satellite, Advanced Land Observing Satellite, and Sentinel‐1 Interferometric Synthetic Aperture Radar (InSAR) time series analysis during episodes of drawdown (1993–2000), recovery (2007–2010), and modern management (2015–2018) in discontinuous observations over a 25‐year period. The observed deformation generally reflects changes in hydraulic head. However, at times during the wellfield recovery, the deformation signal is complex, with patterns of uplift and subsidence suggesting a compartmentalized aquifer system. Recent records of locally high geothermal gradients and an overall warming of the system (~0.5°C during the water level recovery) obtained from repeat temperature measurements between 2013 and 2018 constrain a conceptual model of convective heat transfer that requires a vertical permeable zone near an observed fault. To reproduce observed temperature patterns at monitoring wells, high basal heat flow and convective cooling associated with downward flow of water from cool shallow aquifers during the drawdown period is necessary. The fault, however, appears to die out southward or may be locally permeable, as conceptual cross‐sectional hydrologic modeling reproduces the surface deformation without such a structure. Our work demonstrates the importance of incorporating well‐constrained stratigraphy and structure when modeling near‐surface deformation induced by, for instance, groundwater production.
A simplified method to evaluate geothermal storage in an aquifer with consideration of heat transfer between aquifer and caprock/baserock
Storing and extracting heat during different seasons of the year is possible through the utilization of a ground aquifer with an open loop Ground Source Heat Pump (GSHP) system. Being able to predict the hydrothermal performance of geothermal storage is required for an efficient operation of the system for cooling and heating of buildings. Complex 2D and 3D hydrothermal numerical models can simulate the thermal performance of geothermal storage accurately but often lack the desired computational speed for conducting large number of simulations for performance optimization. Instead, a 1D radial model can be used to conduct fast evaluation. However, it is important that the model computes the amount of heat loss from an aquifer into the overburden and underlying layers accurately to evaluate the amount of geothermal storage in the aquifer at different times. In this study, a source term is introduced into a 1D model to simulate the heat transfer between the aquifer and caprock/baserock in the vertical direction. The following two heat loss models are introduced in the heat advection-conduction equation: (i) Newton’s heating/cooling law, which leads to a closed form solution, and (ii) a conduction-based semi-analytical model, which requires a 1D finite element solution. When compared to a full 2D axisymmetric simulation result, it was found that the Newton’s heating/cooling law model with a constant heat transfer coefficient works well in cases of fast heat flow rate in thick aquifers of around 100 meters. But large errors in estimating heat dissipation are observed in cases with low heat flow rate in thin aquifers, especially for simulations exceeding two to five years. On the other hand, the model with the conduction-based semi-analytical solution gives a better match for these conditions.
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- Award ID(s):
- 1903296
- NSF-PAR ID:
- 10232758
- Editor(s):
- McCartney, J.S.; Tomac, I.
- Date Published:
- Journal Name:
- E3S Web of Conferences
- Volume:
- 205
- ISSN:
- 2267-1242
- Page Range / eLocation ID:
- 07007
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1051/e3sconf/202020507007
