ACIDIC FLUID IN LOS HUMEROS GEOTHERMAL RESERVOIR: A PRELIMINARY OUTLOOK

Abstract

The Los Humeros geothermal system has been considered as being consisted of two reservoirs, although there is no separation layer (lithological unit) between them to differentiate. The shallow reservoir contains vapor and liquid whereas the deeper one has only superheated steam and high temperature (>3OOoC). The production of HCI vapor
in the deeper reservoir is a result of water-rock interaction at high temperature and low amount of water. The high corrosiveness and scaling in the wells due to these deeper fluids has limited the exploitation of only the upper reservoir. The present work compiles the geological and geochemical literature with emphasis on present status of knowledge of the hydrothermal model and physiochemical processes in the reservoir. It has been observed that the production fluid characteristics change with changing well opening.This leads to the conclusion that the well construction parameters have important contribution in controlling the production fluid characteristics. Similarly, the determination of pH of geothermal reservoir fluid is necessary, but it is sufficient to characterize the type, quantity and the origin of acidity. It is fundamental to measure alkalinity and reconstruct the reservoir fluid physiocliemical parameters.