| Abstract |
Present electric price formulation in Indonesia may force increasing MWe/well drilling average to reach economic of geothermal power project. Acquiring high certainty of well targeting becomes a critical process. Based on lessons learned from geothermal exploration and development, fault or fracture targeting is very effective permeable target to increase << 10 MWe well output to >> 10 MWe well output as fault/fracture highly control the behavior of geothermal fluid flow. First part of the process involve identifying key drivers or critical parameters to identify major fault or structure permeability to construct structural play of the area. Detail information of the fault such as rock type/facies type, fault angle and depth are critical part of the assessment. To lower uncertainty of the key drivers the parameters can be separated into surface, subsurface and development phase. During exploration phase, an effective surface program includes detail structure and alteration mapping which effectively distinguished major from minor fault or fracture. Later during initial development, open and closed fault can be distinguished by implementing FMS/FMI (fracture imaging) logging. Also implementation of subsurface program such as micro earthquake (MEQ) survey with moment tensor analysis adds significant value and might give a better fault system and orientation and distribution of stress. One of the problems in well targeting is fault modeling and fracture characterization. A big step forward of subsurface program including research for targeting the well is monitoring a passive seismic, enabling to observe a shear wave splitting to characterize the fault by drilling a shallow well (250 m). A different method for well targeting during development phase is by integrating geomechanical drivers such as proximity to fault, slopes and curvatures of the structure are discussed. This technique has been applied successfully in oil & gas industry to target the well. A subsurface process to target the well by reducing the associated risk has been implemented with the result shows a significant improvement in well output. In this case, the average of 9 MWe/well can be improved to 25 MWe/well based on our experience by applying those technologies. |