Gas Geochemistry of the Los Humeros Geothermal Field, MÈxico

Abstract

Gas data of the Los Humeros geothermal field were analyzed. A new method which is based on equilibrium of the Fischer- Tropsh reaction and on the combined pyrite-hematite and pyrite-magnetite reactions was used. Reservoir temperature and reservoir excess steam were estimated for the initial state of the field by using early data taken from producing wells at controlled conditions. The same parameters were also obtained for the present stage by using 1997 gas data. Reservoir temperatures ranged from 275 to 337?C and positive values for reservoir excess steam fractions were obtained for the starting stage. For well H-1 no excess steam was found since this well was fed by the shallower liquiddominated reservoir. Results for 1997 showed lower scattering compared to earlier data and the possible occurrence of a heating process in the shallower stratum which could be due to exploitation.