Study of Acid Zone Delineation in Mataloko Geothermal Field using The Total Conductance Method
Keywords:
acid fluid, alunite mineral, total conductanceAbstract
Mataloko geothermal field in Ngada Regency, East Nusa Tenggara, is one of the geothermal field in eastern Indonesia that has been in production but has now stopped production. Several hot spring manifestations in the Mataloko are acidic, for example in Wae Luja Hot Stream with pH 2,92 and Wogoalo Hotpool 2 with pH 4. The Mataloko geological logging data also shows that all 5 wells drilled vertically around the fumarole area, have almost the same elevation, contain acidic alunite minerals (pH <4) at a depth of 300-350 m. The gas composition in NCGs, informs that the H2S gas content in the MT-4 well is relatively greater compared to other wells. This indicates that the MT-4 well fluid is slightly acidic. Research is needed to mitigate by creating a map of the estimated distribution of acidic fluid areas. The proposed solution to the problem is to create a map of areas that have acid content in the Mataloko geothermal field using the Total Conductance method with an electrical conductivity approach. From the results of the calculation of the Total Conductance value, the acid zone in the Mataloko geothermal field has a value of ±700 Mhos.
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