Geothermal exploration in Gujarat: case study from Dholera

Abstract

Utilization of Geothermal resources is an alternate, sustainable energy, which needs to be harnessed in India . Exploration of the resource is the first step to understand potential leads and prospects in the subsurface. An attempt has been made to understand the subsurface picture using geoscientific data, for example, Gravity survey, Landsat imagery, magnetotelluric (MT) survey and water chemistry. Dholera, Gujarat is a potential site for geothermal exploration and exploitation, which is the chosen study area. Dholera also falls under proposed Delhi Mumbai Industrial Corridor Development Corporation Limited (DMICDC), making it a suitable candidate for setting up geothermal power plant in future. The energy potential of prospects identified in Dholera through the above-mentioned studies may help industries in creating geothermal power plant and utilization of energy in space heating & district heating/cooling. Dholera is located 30 km away in southwest direction from Dhandhuka village of Ahmedabad district and 60 km away in north direction from city of Bhavnagar (Fig. 1c). Hot springs exist over gravity high, which is the surface manifestation of deep and shallow water sources. Present research focuses on vegetation index for the study area and land surface temperature; alteration of water chemistry in association with subsurface rocks and understanding of subsurface models using Gravity and MT surveys. 2D geoelectric maps and gravity contours have helped in understanding the aquifer geometry and dimensions. 2D resistivity sections depict the aquifer connectivity across Dholera at depths of 3 and 4 km. MT survey suggests that the volcanic rocks are exposed at places. However, it also depicts locations where sediments exist and are sandwiched between basaltic lavas. MT model is also constrained using residual gravity data and corroborates well with the MT data. Present study will help in harnessing the geothermal energy entrapped within the geobodies and also to understand connectivity between the geobodies. These studies were carried out one after the other, to delineate geothermal reservoir and increase the probability of success. The best location for further exploration and exploitation by drilling has been identified by integration of all these methods.