Delineation of the permeable zone using microearthquake data in the geothermal field R

Abstract

Reservoirs are an important component in geothermal systems. Hot fluids accumulate in reservoirs, which consist of thick layers of permeable rock. Micro-earthquake methods can be used to identify the permeable zone in a geothermal system. In particular, observations of micro-earthquake hypocenters provide a promising technique to detect such permeable zones. Determinations of the hypocenters are performed using the single-event determination method. Micro-earthquake hypocenter relocations are performed to obtain more accurate locations and to reduce errors that occur because of inaccurate velocity models. The relocation method that is used in this study is double-difference relocation, which is the most efficient and fastest method available and is capable of generating small errors with no necessity of station corrections. In this study, we use data recordings by 18 stations of the micro-earthquake activity in the geothermal Field R from June to October 2012. The processing data start from raw time series data. The distributions of the relocated hypocenters were then matched to the supporting magnetotelluric and geologic data. The result of this study shows that there is a significant amount of seismic activity on the southern part of Mount R. The distribution of micro-earthquakes forms a cluster and a northwest–southeast structure pattern. The distribution of the hypocenters can be interpreted as the permeable zone beneath the surface, with the northwest– southeast fault pattern as the hydrogeology controller of the geothermal system in the geothermal Field R.