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 × 1014J of thermal energy out of which roughly ∼9.76 × 1013 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.