Analysis of Isotopic Patterns (1985-2003) for the Los Azufres (Mexico) Geothermal Fluids

Abstract

The analysis of chemical and isotopic data of the Los Azufres geothermal fluids indicates that at present, important reservoir changes have occurred regarding unperturbed conditions, obtained in 1987. The changes has been attributed to physical processes at the reservoir due to reinjection and reservoir utilization. According to isotopic data taken before 2000, it was seen that interference of reinjection fluids had minor effects in the northern zone of the field compared with those in the south. Until 2002, reservoir boiling and mixing of reservoir fluids with cooler fluids were the main identified processes. Mixing of reservoir fluids with cooler reinjection waters was observed in the west of the south zone, in wells located close to the reinjection area and towards the center. The 2003 isotopic patterns, that include eight new wells of the northern zone, show that, at present, reinjection interference occurs in both zones.