Isotopic (δ18O, δD) patterns in Los Azufres (Mexico) geothermal fluids related to reservoir exploitation

Evolution of the geothermal fluids at Los Azufres, Mexico, as traced by noble gas isotopes, δ18O, δD, δ13C and 87Sr/86Sr

“…Main tectonic structures, sampled wells (closed circles) and hot springs (open circles) are indicated. The area of re-injection of the used brines, the productive area affected by re-injection, the boiling zone, and the steam-dominated zone as reported by Barragán et al (2005) are also shown. Dashed contours indicate the extension of the boiling zone in the NPZ as inferred from fractionation patterns of noble gases measured in this study.…”

“…The Los Azufres geothermal field has been extensively studied in the past 30 years for its geological and tectonic features (Dobson and Mahood, 1985;Ferrari et al, 1991;Pradal and Robin, 1994), the geochemistry of the fluids (Nieva et al, 1987a;Gonzalez-Partida et al, 2000;Birkle et al, 2001;Gonzalez-Partida et al, 2003;Barragán et al, 2005;Gonzalez-Partida et al, 2005) and the evolution of the power capacity after 25 years of exploitation and re-injection of used brines (Nieva et al, 1987b;Arellano et al, 2005;Barragán et al, 2005;Torres-Rodríguez et al, 2005). Despite the numerous studies carried out, noble gas data are scarce in Los Azufres (Prasolov et al, 1999) with only a few wells having been monitored for He and Ar to study the evolution of fluids as exploitation proceeded (Arriaga, 2002;Barragán et al, 2006).…”

Reservoir Processes Related to Exploitation in Los Azufres (México) Geothermal Field Indicated by Geochemical and Production Monitoring Data

“…When injection fluids consist of recycled produced fluids, the effects of reinjection in two-phase production wells are routinely noticed on the salts increase in the discharged liquid [4] [14] [16]- [18] as was illustrated for well Az-33. However, injected fluids in contact with reservoir rocks are heated and eventually evaporated by boiling, then either as steam or as condensed steam they flow to the production zones of wells.…”

“…7) δ 18 O and δD composition of total discharge fluids. This composition is calculated by using equations 2 and 3 and considering the partition coefficients, which depend on temperature, for every separation step that had occurred previous to sample collection [14].…”

Radium depletion and 210Pb/226Ra disequilibrium of Mar^|^iacute;taro hydrothermal deposits, Los Azufres geothermal field, Mexico

“…Secondary minerals produced by the weathering of volcanic rocks by medium-high temperature hydrother- Barragan et al (2005); Gonzales-Partida et al (2005). Bagnes has been measured twice to check local variability.…”