Heat transfer potential of low-enthalpy geothermal resources in the Eastern Ghats Belt, India

Abstract

Development of geothermal resources is vital for rapidly developing economies like India which are trying to reduce dependence on fossil fuels. The present study investigates the geothermal potential of hot springs at four selected sites within the Eastern Ghats Belt (EGB), a part of the non-volcanic, tectonically stable Indian shield. Reservoir temperatures of the hot springs are constrained at ∼150 °C from geothermometric studies. Monte-Carlo simulations performed to assess the geothermal heat-in-place at these sites reveal a probabilistic resource of P10 (1.47*10¹³ kJ), P50 (1.92*10¹³ kJ), and P90 (2.48*10¹³ kJ). Single-phase wellbore simulations integrated with the geothermometric results constrain the reservoirs to depths shallower than 1.60 km and 2.60 km, that were estimated from earlier studies. Wellbore simulations illustrate that the producing-fluid temperature can be enhanced by ∼35 % when the flow rate is increased from 4.5 m³/hr (the highest measured natural discharge rate) to 11.3 m³/hr using a downhole pump. Addition of insulating layers with thickness <0.005 m to the central production tubing leads to a 22 % increase in the producing fluid temperature. Sensitivity analysis indicates that flow rate and and geothermal gradient have the highest impact on the outlet temperature. Exergy analysis suggests that ∼0.6 MW geothermal plants can be developed for shallow reservoir scenarios. This is the first study demonstrating the feasibility of utilizing the geothermal potential of hot springs in the Indian shield by integrating geo-thermometric analyses with wellbore simulations, and suggests applicability globally to other terranes with similar geological setting.