Ahuachapán Reinjection System Ensurement

Abstract

Ahuachapán geothermal power station, located in the western part of El Salvador has been experiencing challenges with time due to its brine disposals in the Chipilapa area.
Field mass exploitation increase, reinjection well injectivities declination and reinjection facilities constrains have pushed scientists and engineers to look forward to ensure Ahuachapán brine disposal.
In case nothing is done in Ahuachapán reinjection system, a brine disposal crisis could be faced, it was estimated that the existing pumping facility could reach its capacity in few years.
Three possible solutions were analyzed, chemical stimulation, installation and operation of well head reinjection pumps and the installations and operation of new pump in the power station and new reinjection pipeline.
Pumping surface facility numerical model developed with well injectivity behavior with time have shown that for a 5 year period, brine disposal with a moderate power station pumping pressure can be ensured if chemical stimulation of reinjection wells allows them to have an injectivity recovery of 16, 26, 8, 13% for CH10, CH7B, CH7 and CH9 respectively.
Worst scenario regarding chemical stimulation results, allowing an injectivity decrease from present of 25, 38, 14, 23 and 10% for reinjection wells CH10, CH7B, CH7, CH9 and CH9A respectively, shows that brine disposals can be ensured by installation and operation of three well head pumps in reinjection wells CH7B, CH7 and CH9 with maximum operating pressure and flow of 22 bara and 230 kg/s respectively. (16.5, 160, 3 kg/s for CH7B, CH7, CH9 reinjection wells)
Installation and operation of new pump in the power station and a higher pressure rate reinjection pipeline to wells CH7B, CH7 and CH9, have great disadvantages regarding the cost of new reinjection pipeline in comparison with the well head reinjection pumps option.