Reservoir Behaviour of the Los Azufres Geothermal Field, after 16 years of Exploitation

Abstract

Los Azufres geothermal field is located in the Transmexican volcanic belt, at an average elevation of 2800 masl. It is found in a forest area with abundant vegetation, considered forest reservation zone. Drilling activity started in 1976 and in 1982 the generation of electricity began. At present, the installed capacity is 88MW with seven backpressure units of 5 MW each, two binary cycle units of 1.5 MW each and one condensing unit to 50 MW. In order to sustain the generation, steam is supplied from 23 producers wells. Simultaneously brine and condensed steam are produced and injected into six injectors wells. In 16 years of continuous development, have been extracted 82.7 million of tons of steam and generated 6611 GWh of electrical energy. The Los Azufres hydrothermal system was studied thoroughly since the beginning of its exploitation. Currently it is counted on numerous geochemical, production and subsurface log data that permit, in conjunction geological, geophysical and mineralogical studies, to elaborate the conceptual model of the field and to accomplish a reliable analysis about the evolution of the reservoir applying numerical simulators. The average pressure decline in he south zone of the field is .71 bar/ year and in the north zone is .33 bar/year. The south is higher than the north because of the larger extraction of mass and energy. The numerical models show the feasibility to install at least 1770 MW at the north zone and 129 MW at the south, for an exploitation of more than 20 years.