Solute geothermometry of springs and wells of the Los Azufres and Las Tres Vírgenes geothermal fields, Mexico

Abstract

Subsurface reservoir temperatures of two important Mexican geothermal systems (Los Azufres and Las Tres Vírgenes) were estimated by applying all available solute geothermometers for 88 and 56 chemical data measurements of the spring waters and fluids of the deep geothermal wells, respectively. Most of the chemical data for spring water of these two geothermal fields are for HCO 3 water, followed by SO 4 and Cl types. For the Los Azufres geothermal field (LAGF), the reservoir temperatures estimated by Na-K geothermometers for springs of HCO 3 and SO 4 waters, and by Na-Li and Li-Mg geothermometers for Cl water, are close to the average bottom-hole temperature (BHT) of the geothermal wells. However, all reservoir temperatures for spring waters from the Las Tres Vírgenes geothermal field (LTVGF) estimated by all solute geothermometers indicated significantly large differences (low temperatures) compared to the BHT. Evaluation of inferred reservoir temperatures for spring waters of the LAGF and LTVGF suggests that not all springs nor all solute geothermometers provide reliable estimation of the reservoir temperatures. Even though chemical equilibrium probably was not achieved in the water-rock system, Na-K geothermometers for HCO 3 water (peripheral water mainly of meteoric origin with little geothermal component) and SO 4 water (geothermal steam heated) and Na-Li and Li-Mg geothermometers for Cl-rich spring water (fully mature geothermal water) of the LAGF indicated reservoir temperatures close to the BHT. However, in comparison with the geothermometry of spring water of the LAGF and LTVGF, fluid measurements from geothermal wells of these two fields indicated reservoir temperatures in close agreement with their respective BHTs. For the best use of the solute geothermometry for spring water, it is advisable to: (1) chemically classify the springs based on water types; (2) identify and eliminate the discordant outlier observations by considering each water type as a separate sampled population; (3) apply all available solute geothermometers employing a suitable computer program such as SolGeo instead of using some specific, arbitrarily chosen geothermometers; and (4) evaluate the temperatures obtained for each solute geothermometer by considering the subsurface lithology, hydrological conditions, and BHTs or static formation temperatures whenever available.

Three-dimensional thermal sensitivity analysis of cooling of a magma chamber in the Los Azufres geothermal field, Michoacán, Mexico

“…The geology and geochemistry of the area were reported by Campos-Enríquez et al (2005), Cathelineau et al (1987), Dobson and Mahood (1985), Pandarinath (2011), Pandarinath et al (2008, Pradal and Robin (1994), Verma (1985), Verma and Andaverde (1996), and Verma et al (2005), among others. The pre-volcanic basement consists of shales, sandstones, and conglomerates of Eocene to Oligocene age.…”

Solute geothermometry of Cerro Prieto and Los Humeros geothermal fields, Mexico: considerations on chemical characteristics of thermal water

“…) and for geothermal well waters (for example, Güileç 1994;Portugal et al 2000;Verma 2002;González-Partida et al 2003, Pandarinath 2011García-López et al 2014;etc.). It is suggested to apply as many geothermometers as possible and compare the indicated temperatures by considering the lithology of the region and other hydrological processes, as not all thermal waters (springs, fumaroles, geothermal wells) nor all geothermometers provide reliable estimation of the reservoir temperature (Pandarinath 2011;García-López et al 2014). In several applications, significant differences among the estimated and the measured temperatures (bottom hole temperatures (BHT)) have been reported.…”

“…Verma et al (2008) have compiled the available 35 solute geothermometers in the literature and developed computer software (SolGeo) for their application. The literature reveals that there are several studies on the application of these solute geothermometers for thermal springs (for example, Güileç 1994;Simmons et al 1994;Verma et al 2006;Pandarinath 2011;etc. ) and for geothermal well waters (for example, Güileç 1994;Portugal et al 2000;Verma 2002;González-Partida et al 2003, Pandarinath 2011García-López et al 2014;etc.).…”

“…The literature reveals that there are several studies on the application of these solute geothermometers for thermal springs (for example, Güileç 1994;Simmons et al 1994;Verma et al 2006;Pandarinath 2011;etc. ) and for geothermal well waters (for example, Güileç 1994;Portugal et al 2000;Verma 2002;González-Partida et al 2003, Pandarinath 2011García-López et al 2014;etc.). It is suggested to apply as many geothermometers as possible and compare the indicated temperatures by considering the lithology of the region and other hydrological processes, as not all thermal waters (springs, fumaroles, geothermal wells) nor all geothermometers provide reliable estimation of the reservoir temperature (Pandarinath 2011;García-López et al 2014).…”

Hydrogeochemical Characteristics and Geothermometry Applications of Thermal Waters in Coastal Xinzhou and Shenzao Geothermal Fields, Guangdong, China

“…To get an accurate estimation, the reliability of these solute geothermometers was also evaluated by comparing the measured bottom-hole temperature (BHT) of the geothermal wells ( Table 9). The following formula used for this comparison is developed by Pandarinath (2011) [59]:…”