Sustainability analysis of the Ahuachapán geothermal field: management and modeling

Abstract

The Ahuachapán geothermal field (AGF) is located in north western El Salvador. To date, 53 wells (20 producers and 8 injectors) have been drilled in the Ahuachapán geothermal field and the adjacent Chipilapa area. Over the past 33 years, 550 Mtonnes have been extracted from the reservoir, and the reservoir pressure has declined by more than 15 bars. By 1985, the large pressure drawdown due to over-exploitation of the resource reduced the power generation capacity to only 45 MW e. Several activities were carried out in the period 1997–2005 as part of “stabilization” and “optimization” projects to increase the electric energy generation to 85 MW e, with a total mass extraction of 850 kg/s. LaGeo is assessing the sustainability of geothermal reservoir utilization. Preliminary results indicate the planned power production and mass extraction (95 MW, 900 kg/s) cannot be sustained for more than 50 years using current power plant technology. To sustain the exploitation for at least 100 years, the following changes should be implemented: (1) improve the gathering system using large-diameter steam pipelines, (2) expand the exploitation area to the southeast and southwest, and (3) reduce the inlet pressure of the turbines to less than 4 bars.