Status of Investigation at Tatapani Geothermal Field, District Surguja and Future Perspective

Abstract

Tatapani geothermal field is the most promising geothermal resource in Central India. Investigations for assessment of geothermal resource at Tatapani, Surguja district, were carried out over two decades. Geochemical survey at Tatapani has revealed 60 to 110 ppm each of Na, Cl, SO4 content, 123 to 161 ppm SiO2, low K, B, Mg and 15 to 20 ppm F content. The thermal water is immature water, which shows mixing with ground water. The source water is meteoric in origin and indicated reservoir temperature is 150?-160?C by quartz geothermometer and 180?-190? C by Na/K method. The above observations are supported by fluid inclusion studies, which measured Th median of 180? to 200? C. Hydrothermal alteration studies, have reported stilbite, smectite, illite, calcite and epidote in thin sections, indicating that the geothermal system operated in the temperature range of 180?C to 250?C.
Five shallow production wells have been drilled in Tatapani upto maximum depth of 350m. Maximum temperature of 112.5?C was reported in the boreholes during well testing. The five production wells recorded discharge of 1800 lpm initially. Present discharge is 1125 lpm from four bore wells. A 300 kWe binary pilot plant was proposed for utilizing present discharge.
Geophysical investigations have suggested aquifer zones at the depth of 300m and around 600m. MT survey indicated that the geothermal reservoir might continue at deeper level. Geothermal resource potential of 11 to 18 MWe was estimated based on the available data. Drilling to the depth of >1500 m is essential for assessing geothermal potential of the deep reservoir. Deep exploration may yield two-phase reservoir conditions suitable for power production.