Geochemistry at Momotombo, Nicaragua: One Aspect in a Geothermal Field Case History

Abstract

The Momobombo area was chosen for geothermal development after a number of sites were investigated in western Nicaragua. Geothermometry from several springs at Momotombi indicated subsurface temperatures might range from 153° to 200°C. The geothermometers in subsequent deep exploration wells and measured temperuates were much higher, suggesting the surface thermal water re-equilibrated with the near surface environment. Preliminary interpretation of some 1979 flow test data shows a change in the flow regime of some wells. Other subtle changes such as correlated variations between SiO2 and K or salinity and Mg shifts, could result form change in flow among producing horizons. Geochemical temperatures bases on the recent dtate ranged from 210° to 324° C. the Na-K-Ca , Ca-K and Sio2 geothermometers were used and seem adequate for monitoring the field. Comparison of the boron content in liquid and steam separation temperatures in those wells where a change in flow regime occurred. The main body of data is given in a synoptic table.