Acid Treatment in Wells of the Los Azufres Geothermal Field to Steam Production Enhancement

Abstract

Los Azufres geothermal field is located in the central portion of México in the volcanic belt at an average elevation of 2800 m. It has been under commercial exploitation producing electrical energy since 1982. At present, the installed capacity is 188 MW with seven backpressure units of 5 MW each, two binary cycle units of 1.5 MW each, one condensing unit of 50 MW and four condensing units of 25 MW each. In order to establish the best exploitation strategy of the geothermal reservoir, production declining analysis has been performed in each well, as well as a diagnostic of the mechanical and thermodynamic state. From the results it has been established which wells, based on their condition, were candidates for injection of acid in order to recover initial production or to improve it. The wells that have been acid treated with successful results are the following ones: Az-2A, Az-8, Az-9A, Az-9AD, Az-25, Az-52, Az-56R, Az-68. The most remarkably case is the Az-9AD, which was producing 25 t/h and after the stimulation increased its production by 188%, producing 47 t/h more than before.