| Title | Reservoir Review of the Rendingan-Ulubelu-Waypanas (RUW) Geothermal Field, Lampung, Indonesia |
|---|---|
| Authors | Suharno |
| Year | 2013 |
| Conference | Geothermal Resources Council Transactions |
| Keywords | Rendingan-Ulubelu-waypanas; hydrothemal-mineral; fluid inclusions; two phases; cooling |
| Abstract | The Rendingan-Ulubelu-waypanas (RUW) geothermal system contains host rocks that alter very readily because of the great contrast between their hydrothermal environment and the volcanic conditions under which they formed. Most surface rocks are weathered but some have also been altered hydrothermally. The alteration includes both replacement of primary phases and the products of processes that affected ascending thermal fluids. Alkali chloride water of near neutral pH once deposited silica sinter at the surface but now acid steam condensate is forming kaolin, silica residue and other phases. The mineralogy, fluid inclusions and surface manifestation indicate that conditions in the RUW geothermal system changed spatially and temporally during its lifetime. The mineralogical evidence incompletely records some of the changes in the thermal regime. The identities of the hydrothermal minerals reflect the new environment in which reservoir rocks find themselves. The main hydrothermal mineral assemblages were produced by neutral pH waters. The Th values are higher than the present well temperatures suggesting cooling has occurred since the inclusions formed. The RUW reservoir contains vapor, two phase and liquid dominated domains but is overall a liquid-vapor dominated system. This is revealed by the well measurements (T and P) and the hydrothermal alteration and fluid inclusions geothermometry. |