PREDICTION OF CONDENSATION ZONE FLUID CHARACTERISTICS: PH AND MINERAL EQUILIBRIUM USING PHREEQC SOFTWARE IN ATADEI GEOTHERMAL FIELD, EAST NUSA TENGGARA
In 2004, exploration wells AT-1 and AT-2 were drilled in the Watuwawer caldera but no water or steam was found. Based on the results of drilling wells AT-1 and AT-2 at a depth interval of 737 - 776 m and 677 - 750 m, pyrophyllite and dickite minerals were found associated with pyrite and secondar...
Saved in:
| Main Author: | |
|---|---|
| Format: | Theses |
| Language: | Indonesia |
| Subjects: | |
| Online Access: | https://digilib.itb.ac.id/gdl/view/87894 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | In 2004, exploration wells AT-1 and AT-2 were drilled in the Watuwawer caldera
but no water or steam was found. Based on the results of drilling wells AT-1 and
AT-2 at a depth interval of 737 - 776 m and 677 - 750 m, pyrophyllite and dickite
minerals were found associated with pyrite and secondary quartz minerals so the
hydrothermal fluid is suspected to be of the chloride sulfate type with a pH tending
to be acidic. In 2021, PTS (Pressure-Temperatur-Spinner) logging was conducted
to analyze the temperatur, pressure, and flow rate of reservoir characterization of
wells AT-1 and AT-2. From the spinner log results, fluid movement was observed,
as indicated by changes in the gas phase to saturation conditions. However,
condensation water sampling from the wellheads of AT-1 and AT-2 was
unsuccessful, as no condensed water could be produced. Since condensate samples
from the wells could not flow to the surface, the estimation of fluid characteristics
in the condensation zone was conducted using geochemical modeling, following the
method of R. Karolyt? (2017). From the MAP WWU, WTU and WKR, it is known
that the hot springs in the Watuwawer system have a temperatur of <40°C, are
bicarbonate type, included in immature water so that they do not characterize fluids
from deep reservoirs and are not representative for modeling. Mineral saturation
in manifestations (SI>0) in equilibrium conditions is saturated by quartz and
calcite while anhydrite minerals are in unsaturated conditions with solutions.
Geochemical modeling was carried out with PHREEQC software using the
PHREEQC.dat database to reconstruct and estimate the characteristics of the
shallow condensation zone. In R Karolyt? (2017), modeling was carried out by
reacting fluids - rocks and dissolved gases at shallow depth temperaturs. From the
results of geochemical modeling, in the condensation zone at a depth of 320 - 340
m, temperatur 129 - 145 ° C it is known that the fluid characteristics tend to be
acidic with a pH range of pH 4.8 - 4.9. This acidic pH is thought to be due to the
presence of dissolved gases that react in the condensation zone, namely CO2 and
H2S gases. From the results of geochemical modeling and composite log
comparison, it is known that minerals with SI values > 0 include montmorillonite
((Na,Ca)0.33(Al,Mg)2Si4O10(OH)2.nH2O), kaolinite (Al2Si2O5(OH)4), quartz (SiO2)
and pyrite (FeS2). |
|---|