Response to Exploitation of the Los Azufres (Mexico) Geothermal Reservoir

Abstract

The response to exploitation of the Los Azufres geothermal reservoir was investigated through the evolution of thermodynamic patterns of reservoir fluids. The study comprised the period since the beginning of exploitation in 1982 to 2002. Thermodynamic conditions of reservoir fluids were obtained by heat and fluid flow simulation in wells using the "WELFLO" simulator and well production data as input. The initial thermodynamic conditions of fluids in the north zone of the field were located in the compressed liquid region while the first response to exploitation consisted on a pressure decrease and an enthalpy increase in wells. The long term response implies very small changes in pressure but large enthalpy increments. For the south zone wells, the initial thermodynamic conditions indicated the presence of compressed liquid, two phase fluid and steam. The first response to exploitation, was noticed through a pressure decrease and an enthalpy increase in wells, while the processes for the long term response are as follows: decrease in both pressure and mass flowrate, boiling, cooling, steam production and in wells affected by reinjection, an increase in both pressure and mass flow rate.