A Study of a Technology for Optimizing Design of Micro-Earthquake Monitoring Network Systems in Geothermal Fields

Abstract

Microearthquakes are triggered in geothermal fields when fluids are withdrawn from or re-injected into geothermal reservoirs. Using microearthquake monitoring, it is possible to delineate geothermal reservoir boundaries and the flow paths of geothermal fluids by precisely measuring changes in the distribution of microearthquake hypocenters. To accurately locate the hypocenters, it is essential to design an optimum microearthquake monitoring network system. Tor this purpose a conceptual design of a microearthquake monitoring system, to detect changes in heat and mass flow in geothermal reservoirs, was studied, In order to optimize a microearthquyake monitoring network, we conducted a detectability simulation, a hypocentral accuracy simulation and a sensitivity study on the Kakkonda network of stations. Consequently, it was proved that the detectability and htpocentral accuracy simulations are very effective for designing the best possible network. We confimed that the detectability simulation is reliable by comparing its results to observed microearthquakes in the Kakkinda field. We also established general guidelines in designing a network of seismic stations.