Sokoria Geothermal Field is situated about 37 km northeastern part of Ende city, belong to the administrative region of Sokoria village, district of East Ndona, Ende regency, East Nusa Tenggara. The thermal gradient well of the Sokoria geothermal field consists of 2 wells, those are SK-1 and SK-2. Geographically, SK-1 and SK-2 are respectively located at 121° 45’ 58” East - 08° 47’ 25” South and 121° 45’ 59” East - 08° 47’ 10” South.
Rock unit of SK-1 from top to bottom consists of Top Soil, Tuff Breccia, Andesite, Altered Andesite, Altered Andesite Breccia and Altered Andesite Basaltic, whereas SK-2 composes of Altered Andesite, Altered Andesite Breccia and Altered Andesite Basaltic. An interbedding occurred among Altered Andesite, Altered Andesite Breccia and Altered Andesite Basaltic characterize the rock originating from several times of eruption periods of the Mutubasa Volcano in the Mutubasa’s old caldera.
The entirely rock have undergone a hydrothermal alteration with a varied alteration intensity from weak to intense (SM/TM = 10-85%). The hydrothermal alteration is generally characterized by processes of argilitization, oxidation with/without piritization, silicification, carbonatization, anhydritization and chloritization. The type of alteration is included into “Argillic” functioning as caprock in the geothermal field of Sokoria. The environment setting of alteration mineral indicates a netral to acid fluid condition characterizing its formation on a high-temperature of hot water and vapour system.
From the result of temperature logging measurement it has been obtained an anomaly of average temperature at SK-1 by 13 times normal thermal gradient, that is about 40 deg C/100 m, whereas SK-2 has an anomaly of average temperature by 12,6 times normal thermal gradient, that is about 37,8 deg C/100 m. Based on the result of geological analysis and temperature logging measurement show subsurface heat flow at the field of Sokoria and it has a prospect to be developed further.
