Continuous Measurement of Gases for Effective Geothermal Reservoir Management and Earthquake Prediction

Abstract

An on-line Modular Environmental Data Acquisition System (MEDAS) at MG5D pad in Mahanagdong sector of the Leyte Geothermal Production Field continuously monitors the presence of radon gas and other chemical parameters in the geothermal brine and steam. Radon gases are to be used as indicator of any major fault movement or earthquake in the field. Other parameters like conductivity, redox potential and CO2 concentrations will be applied as possible additional tools in geothermal reservoir management. Initial results indicate that wells MG18D, MG9D, MG23D and MG32D that were drilled through different fault structures have distinct levels of radon concentration. Anomalies in the level of radon in each well, therefore, could be attributed to specific faults intercepted by the wells. Among the other parameters monitored, significant changes were observed in the conductivity values of MG23D and redox potential in MG18D. Additional on-line monitoring data has to be established to determine what causes these changes in the geothermal reservoir in correlation with standard chemical monitoring parameters.