B-VALUE CHARACTERISTIC AT WAYANG WINDU GEOTHERMAL RESERVOIR

• Main Author: SYAHPUTRA MULYANA (22616016), REZA
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/30375
• Institution: Institut Teknologi Bandung

<p align="justify">The study of the subsurface conditions of a geothermal field is needed to get a clear picture of the condition of the reservoir. Reservoir conditions can be known based on physical properties of subsurface conditions ranging from lithology to fluid condition in a geothermal reservoir. Reservoir conditions of a geothermal field that has been developed will have different characteristics from the beginning of the production process, in order to know the characteristics of the reservoir, an analysis is needed using microseismic data which is measured continuously. <br /> <br /> Wayang windu geothermal field has been developed since 1996, recently the field has generated 227 MW of electricity and will continue to be developed, therefore a study of reservoir characteristics is needed to support the long lasting development of the field. In 2016, 15 seismometer measurement stations were installed in the Wayang Windu geothermal field. During a period of 6 months from January to June, there were identified 644 microearthquake events in the Wayang Windu geothermal field and its surroundings. In the calculating process to describe the variations of b-value anomalies, parameters of moment magnitude (Mw) and earthquake hypocenter location that happened in the study area. The value of moment magnitude (Mw) for each earthquake that occurred in the study area had a range of -1.95 to 2.07 with a hypocenter distribution which formed 4 clusters, namely the Gunung Kencana cluster, the Darajat cluster, the northern Wayang Windu cluster, and the nouthern Wayang Windu cluster. <br /> <br /> Spatial analysis of b-value anomalies illustrates different reservoir characteristics between the northern Wayang Windu cluster and the southern Wayang Windu cluster. The characteristics of the geothermal field reservoir in the southern Wayang Windu cluster have relatively high values, ranging from 1.8 to 2.2 due to the presence of large pore pressure values that comes from water injection to the reservoir. The characteristics of the Wayang Windu reservoir in the northern cluster have relatively low b-value anomalies, 1,2 to 2,2 which are interpreted as the influence of the presence of vapor zones in the area.<p align="justify">