STUDY OF HYDROTERMAL ALTERATION AND WATER GEOCHEMICAL TO DETERMINE FLUID CHARACTERISTICS IN LILLI SEPPORAKI GEOTHERMAL FIELD, WEST SULAWESI, INDONESIA
The Lilli Sepporaki Geothermal Field is located in Polewali Mandar Regency, West Sulawesi Province. This field is associated with Tertiary volcanic activity. This field has four manifestations of hot springs with temperatures between 60.9oC to 97oC. This study aims to understand the alteration pr...
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| Format: | Final Project |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/69717 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | The Lilli Sepporaki Geothermal Field is located in Polewali Mandar Regency, West
Sulawesi Province. This field is associated with Tertiary volcanic activity. This field
has four manifestations of hot springs with temperatures between 60.9oC to 97oC. This
study aims to understand the alteration process and fluid characteristics by
determining the lithology and alteration below the surface and the geochemistry of
water from the manifestations on the surface.
This study uses primary data in the form of drill cores drilled from wells LLK-1 and
LLK-2 with a depth of 700 m for each well. This study also uses secondary data in the
form of water chemistry data on surface manifestations, as well as geological and
geophysical data in the research area. The analytical methods used include
petrological analysis, petrography, X-Ray Diffraction (XRD), and water geochemistry.
The lithology of LLK-1 and LLK-2 is a volcanic product consisting of lapilli tuff,
pyroxene andesite, and biotite andesite. All of these lithologies are equivalent to the
Eocene Inseparable Volcanic Unit. The alteration process in both wells is in the form
of primary mineral replacement and open space filling, with the intensity of alteration
in the sample being weak to moderate. The alteration zone in the LLK-1 and LLK-2
wells consists of the smectite-quartz-calcite-chlorite-pyrite alteration zone and the
smectite-quartz-calcite-chlorite-pyrite-epidote alteration zone. The veins in the LLK-1
and LLK-2 wells are filled with the minerals quartz, epidote, and calcite.
The geothermal system in the research area currently consists of 2 systems, namely the
Sepporaki System and the Weighing System. The source of water in these two systems
is meteoric water which is heated by the remaining heat from the intrusive rock that is
not exposed. The water then comes out as hot springs through the weak fault plane.
The Sepporaki Geothermal System has a chloride water reservoir and is partial
equilibrium with a reservoir temperature of 170 ± 10°C (with Quartz Geothermometer,
Na-K-Ca and Na/K), while the Kaimbang Geothermal System has a chloridebicarbonate
water reservoir and is partial equilibrium, has a reservoir temperature of
150 ± 10°C (with Quartz Geothermometer and Na-K-Ca). |
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