Field development plan of geothermal hotspot in eastern India: A case study from Bhimband, Bihar

Bhimband, located in Bihar in eastern India hosts a well-known geothermal system that appears to be strongly influenced by fault-controlled circulation, and the surface springs there routinely reach temperatures of about 60-65 °C. In this research, the geothermal environment was analyzed using a combination of geological observations and a number of geophysical surveys, including gravity, magnetic, and electrical resistivity surveys to gain a better understanding of the subsurface environment and heat flow characteristics. Using these data, a probabilistic volumetric assessment was carried out through Monte Carlo simulations and the results indicate that the region may store on the order of ∼6.50 × 10 14 J of thermal energy out of which roughly ∼9.76 × 10 13 J could realistically be recovered. Based on these findings, a preliminary field development strategy was outlined for a small-scale binary power plant (∼3.1 MW) operating on an Organic Rankine Cycle and designed for a 20-year life. The plan suggests a phased drilling program of 24 wells which includes exploration, appraisal, production and reinjection wells, arranged in a manner that would allow long-term and balanced extraction of heat. The revised economic analysis estimates a CAPEX of ₹86.5 crore and OPEX of ₹45 crore over 20 years, resulting in a simple payback period of ∼20 years and an IRR of ∼8%, reflecting the high upfront investment and modest project scale. The environmental factors were incorporated into the design with a focus on reinjecting the cooled fluid to maintain the reservoir pressure and minimize surface emissions. On the whole, the assessment tends towards the technical feasibility of geothermal power production at Bhimband and provides a useful initial framework for sustainable geothermal development in India, in the wake of the country's increasing interest in clean energy alternative. • This study presents a comprehensive geothermal resource assessment by integrating detailed geological investigations with geophysical surveys (gravity, magnetic, and electrical resistivity) to characterize subsurface conditions and evaluate the geothermal potential of the study area. • The interpreted geophysical and geological data were further utilized in a probabilistic volumetric resource estimation using Monte Carlo simulation, which indicates a total stored thermal energy of approximately 2.7 × 10 14 J, with about 4 × 10 13 J estimated as technically recoverable. • Based on the estimated resource potential, a 1.3 MW binary Organic Rankine Cycle (ORC) power plant is proposed as part of a conceptual Field Development Plan (FDP). • Preliminary economic modelling estimates a capital expenditure (CAPEX) of around ₹83 crore and an operating expenditure (OPEX) of approximately ₹45 crore .