Re-visiting Geothermal Fluid Circulation, Reservoir Depth and Temperature of Geothermal Springs of India

Abstract

• Most of the thermal water are of immature water type. • Four major water types were identified in four major geothermal provinces. • For the Himalayan springs, water–rock interaction are dominant at depths. • The reservoir temperature of the Himalayan and the west coast springs are higher. • The fluid circulation depth for the Himalayas are deeper (∼2.14 km). Stringent pollution control regulations and sustainable development goals have renewed the interest in finding an alternate, renewable, and sustainable energy resource. Geothermal energy is one such potential source, which needs to be explored. This study deals with the geochemical characteristics and reservoir parameters of the major hot springs located in four diverse terrains in India, as well as their energy potential in terms of reservoir temperature. The west coast springs have mostly Na-Cl, Ca-SO 4 , and Na-HCO 3 water types, and are likely to be influenced by seawater intrusion through deep penetrating faults and fractures, whereas the Odisha hot springs show immature water of Na-Cl, Ca-HCO 3 types. The West Bengal springs show Na-Cl-HCO 3 water type, presumably derived from dissolution of albite at higher temperatures at depths (∼1.13 km). The Himalayan springs water are mostly of NaHCO 3 , CaHCO 3 , NaCl, and CaSO 4 types, and are geochemically more diversified compared to the west coast, West Bengal, and Odisha hot springs. The estimated reservoir temperatures and reservoir depths are 150 ± 10 °C, and 2.11 ± 0.2 km; 120 ± 5 °C, and 1.71 ± 0.17 km; 100 ± 5 °C and 1.13 ± 0.13 km; 110 ± 5 °C and 1.37 ± 0.32 km for the Himalayan, west coast, West Bengal and the Odisha geothermal systems, respectively.