Overview of Microseismic Play as Monitoring Geothermal Reservoir Sustainable in Indonesia

Guspudin, Bagus; Mohamad, Febriwan; Triastuty, Hetty

Indonesia is a country that has large potential of geothermal energy from Sumatra island, Java, Nusa Tenggara, and also in Sulawesi, especially in North Sulawesi. Indonesia has large potential of geothermal resources which is about 28.5 GWe (Geological Survey, 2009). This potential is equivalent to 12 billion barrels of oil to the operation of 30 years. Geothermal exploration has been developed in many regions in Indonesia by using concepts such as Geomagnetic, Resistivity or Magnetoteluric. Then, in the exploitation phase will be done and to control those activities required monitoring activities on geothermal reserves in order to the fractures and reservoir conditions can be monitored periodically. One of the methods used for continuous monitoring in Indonesia geothermal industries is Microseismic. We will get a variety of problems if not conducted monitoring, for example: (1) we don't know about the direction of fracture in the reservoir. And (2) we don't know about condition of reservoir which is the source point for injection fluid.

In principle, Microseismic serves to record seismic events caused by small earthquakes occurring below the surface of the earth. Micro seismic used by installing a network receiver or geophone using a specific pattern and caught maximal event. The source of the waves is the extraction fluid as result exploitation of geothermal generating cracks on Enhanced Geothermal System which is occurs during injection and production. But the number of events and small magnitude are typically used to become a source of injection wells to increase the number of events recorded by the receiver. Injection of the wells doing expected to occur hydraulic fracturing or thermal shock event that become microseismic event.

Microseismic used for monitoring changes in the character of reservoir (the direction of fluid flow, density and direction of fracture) by emerge of instability reservoir (changes in temperature, pressure causing fracture), measuring seismic events caused by the presence of fracture, production and fluid injection. By using the Microseismic monitoring is expected to increase geothermal production as necessary a lot of people in Indonesia and that concept can developed by Indonesia geothermal industries.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013