4.4 Interpretations The data collected from this study are not strongly affected by convective fluid flow in the wellbores or surrounding strata. Rather, the geothermal gradient profiles show a more conductive thermal regime in the vicinity of the wells. Unfortunately, the wells are too shallow to make more significant observations of the deep thermal regime, but the high geothermal gradients in the Paliza Canyon and E10 wells show some promise of quantifying temperatures of a geothermal reservoir at ~900 m depth that may be explained using a transient model for the flow of warm water at depth.
4.4.1 Geothermal gradient profiles and their projected temperatures at depth The constant geothermal gradient from the JP Water Wells is slightly …show more content…
Thermal conductivity changes are most likely due to significant changes in lithology such as sand (~1.7 – 4.0 W/m/K) to clay (~1.0 – 1.5 W/m/K) or limestone (~1 – 3 W/m/K) (Robertson, 1988). Since these wells were drilled primarily through Triassic sediments, containing mudstone, shale, and sandstone intervals, changes in the thermal conductivity of the strata could explain the behavior of the temperature profile. The only lithologic log that has been run closest to these well bores is the stratigraphic log plotted with temperature for the AET-4 well (Figure 4.6, from Shevenell et al., 1988 – Figure 3). The figure illustrates how the gradient changes with lithology in the Permian section and fluid flow. However, the E10 and Paliza Canyon wells are too shallow and do not penetrate the Permian section and the Triassic section was mostly removed at the AET-4 location prior to the deposition of the Bandelier Tuff; thus direct comparison with the lithologic log at AET-4 is not …show more content…
Much like the AET-4 well, the rock units adjacent to the wellbores may have been heated by a hot fluid flowing laterally in an aquifer, but below the bottom of the well. Harrison et al. (1986) applied the Ziagos and Balckwell (1986) model for the transient temperature effects of horizontal fluid flow through an aquifer to temperature data from the Hot Dry Rock experiment and the AET-4 well. According to the model for the EE-2 well at Fenton Hill, a pulse of liquid at 80 °C flowing at ~800 m depth would take 10,000 years to raise the temperature gradient above the aquifer to its present conditions. Harrison et al. (1986) similarly concluded the age of heating for the AET-4 well at 900 m depth to be on the order of less than 1,000 years, but that conclusion was based on the shape of the gradient, i.e. a sharp peak at the depth of the aquifer. However, those conclusions were vague and the model parameters and results were not presented in
4.4.1 Geothermal gradient profiles and their projected temperatures at depth The constant geothermal gradient from the JP Water Wells is slightly …show more content…
Thermal conductivity changes are most likely due to significant changes in lithology such as sand (~1.7 – 4.0 W/m/K) to clay (~1.0 – 1.5 W/m/K) or limestone (~1 – 3 W/m/K) (Robertson, 1988). Since these wells were drilled primarily through Triassic sediments, containing mudstone, shale, and sandstone intervals, changes in the thermal conductivity of the strata could explain the behavior of the temperature profile. The only lithologic log that has been run closest to these well bores is the stratigraphic log plotted with temperature for the AET-4 well (Figure 4.6, from Shevenell et al., 1988 – Figure 3). The figure illustrates how the gradient changes with lithology in the Permian section and fluid flow. However, the E10 and Paliza Canyon wells are too shallow and do not penetrate the Permian section and the Triassic section was mostly removed at the AET-4 location prior to the deposition of the Bandelier Tuff; thus direct comparison with the lithologic log at AET-4 is not …show more content…
Much like the AET-4 well, the rock units adjacent to the wellbores may have been heated by a hot fluid flowing laterally in an aquifer, but below the bottom of the well. Harrison et al. (1986) applied the Ziagos and Balckwell (1986) model for the transient temperature effects of horizontal fluid flow through an aquifer to temperature data from the Hot Dry Rock experiment and the AET-4 well. According to the model for the EE-2 well at Fenton Hill, a pulse of liquid at 80 °C flowing at ~800 m depth would take 10,000 years to raise the temperature gradient above the aquifer to its present conditions. Harrison et al. (1986) similarly concluded the age of heating for the AET-4 well at 900 m depth to be on the order of less than 1,000 years, but that conclusion was based on the shape of the gradient, i.e. a sharp peak at the depth of the aquifer. However, those conclusions were vague and the model parameters and results were not presented in