APPLICATIONS OF MICROSEISMIC MONITORING IN GEOTHERMAL RESERVOIR


        Magnetotelluric method usually used for geothermal exploration. But, fault and fracture areas usually use microseismic to get image of subsurface structure. In this case, it will be able to be reached if the ratio between seismic signal and noise is high. Seismic sources in geothermal field are fault and fracture induced by tectonic movement, volcanic, or fluid movement on subsurface. Both fault and fracture induce Microearthquake which the magnitude 1 until 3 Richter scale. Configuration acquisition is made far and near station because it is better to determine point the local earthquake. Station on target is used to get vertical accuracy. Far field is used to lateral accuracy and margin characterization. So, the result of acquisition is t0, x, y & z data that require at least 4 seismograph from 4 stations.

         Hypocenter is determined from the spreading of SED (Single Event Determination) method. The program also reads waveform data, trimming, and picking from P and S wave. Furthermore, JHD (Joint Hypocenter Determination) and DD (Double Difference) method is used to relocation hypocenter. Position of hypocenter has different minimum between observation time and calculation. Moreover, Matlab program is used to make residual or error. We are also shown 3 circles method. The configuration is better to determine local earthquake. The configuration can catch vertical correction. In interpretation, we wish to get 4 targets include; temperature, shape and depth, acidity level, and permeable or not.

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