| Title | Feedzone Characterization in Geothermal Reservoir: Integration of Borehole Image, Spinner and Loss Circulation Data |
|---|---|
| Authors | M Ikhwan AZIZ, Graniko Reza PRATAMA, Imam M PRASETYO, M Husni THAMRIN |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | Feedzone, Borehole Image, Spinner, Loss Circulation, Permeability |
| Abstract | It is believed that the contributing factors that provide permeability in a volcanic hosted geothermal reservoir are fault and fracture. However, it does not rule out the presence of other that may also provide the conduit for the fluid to flow. To locate these permeable zones, borehole image data together with the spinner and loss circulation data from drilling are used. The data were taken from wells of different geothermal fields operated by PT. Pertamina Geothermal Energy (PGE). From this study, fracture and fault are the main sources of permeability that can drain the fluid with the greatest amount. However, The spinner response also occured on the lythological contact as seen on the borehole image. It shows no fault or fractures develop within this depth range. From the drill cuttings and image logging analysis, It suggests that the permeability derived from lithological contact zone is commonly composed of two lithology that genetically have different forming process (eg lava and pyroclastic or intrusive body contact). In addition, permeability also exists in a particular lithology such as pyroclastic. The void between the fragments and/or matrix that play a major role in providing the primary permeability. The outcome of this study is to understand the contributing factors that provide the permeability in a volcanic hosted geothermal reservoir. It also complements for geothermal well targeting by probing the best possibilities in the subsurface that potentially provide a productive aquifer. |