Investigation of geothermal energy potential using electrical resistivity survey and chemical geothermometers: a study of the manghopir hot spring karachi, sindh pakistan

Electrical resistivity survey and chemical geothermometers methods were used to find the geothermal gradient energy potential of the Manghopir hot spring which is located in Karachi, Sindh. Schlumberger electrode configurations were used to demarcate the two shallow potential subsurface aquifers. At various depths, three lithological units were encountered: alluvium, sandstone, and shale. The first thermal water aquifer lies below at the average depth of 10m and average thickness of 9 m lies in sandstone lithology of Nari Formation of Oligocene age. The second thermal water aquifer encountered at the average depth of 68 m and the average thickness of aquifer was 40.5m in sandstone lithology of Nari Formation. The surface water temperature was calculated with digital thermometer which shows the range in between 48 °C to 50 °C and subsurface temperature was calculated with the help of chemical geothermometers. The Na–K geothermometers indicate the subsurface equilibrium reservoir temperature in the range of 135.52 °C,125.54 °C, 172.964 °C and 184.08°C and the Na-K-Ca chemical geothermometers indicate the subsurface reservoir temperature 148.493°C. The Na-K-Ca geothermometers show a high temperature, but the reservoir temperature appears to be lower due to the mixing of sea water with the chemical composition of hot spring water within the subsurface aquifers.