PARENT FLUID AND FLUID FLOW STUDY OF SONGA-WAYAUA, SOUTH HALMAHERA GEOTHERMAL RESERVOIR BASED ON WATER GEOCHEMISTRY
| Main Authors: | Kencana, Aditya yuda, Herdianita, Niniek Rina |
|---|---|
| Format: | Proceeding PeerReviewed application/pdf |
| Bahasa: | eng |
| Terbitan: |
, 2019
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| Subjects: | |
| Online Access: |
https://repository.ugm.ac.id/275732/1/C030UNO.pdf https://repository.ugm.ac.id/275732/ |
Daftar Isi:
- Geologically, Songa-Wayaua located on the Halmahera volcanic arc. The are several volcanoes such as Lansa and Bibinoi, and geological structures such as Wayaua, Lapan, Pele and Tawa faults. The presence of the geothermal system in the Songa-Wayaua field is characterized by hot springs, fumaroles, and altered rocks. The manifestations of hot springs that present are Songa hot springs (MAPS 1, MAPS 2, and MAPS 3) and Wayaua (MAPW). Fumarole was discharged at the MAPS 1 and MAPS 2. This study aimed to determine the parent fluid chemistry, temperature, and pH in the reservoir and hydrothermal fluid flow. The analysis was used anions and cations of hotsprings. Based on the analysis results, the fluid that appears as a manifestation has boiled in subsurface at 131 ̊C and 103.5 ̊C, then mixed with sea water. The mixed seawater fraction and the fractions of water and steam when boiling were calculated using the heat balance and mass balance. From the calculation, the results show that there are two Cl/B ratio clusters. The first cluster consists of MAPS 1, MAPS 2, and MAPS 3. While the second cluster is MAPW. These are interpreted that there are two different reservoirs. This is supported by the geological conditions of the two spring zones separated by a normal fault located in Songa-Wayaua bay. Based on the Giggenbach Na-K geothermometer, Songa reservoir temperature was 250 ± 10 ̊C and Wayaua reservoir was 175 ± 10 ̊C. The results of H2CO3 and CaCO3 equilibrium analysis show the pH of the two reservoirs included in the neutral to slightly basic fluid valued at 5.45 – 8.44. So that it is interpreted that the MAPS 1 and MAPS 2 springs discharge in the upflow zone, which are also indicated by fumarole discharge and Na/K ratio 15.