Reassessment of the resources and hydrochemistry assessment of the Devin hydrothermal mineral deposit, Smolyan region

The recent study presents main results of a re-evaluation of the mineral water and geothermal energy of the Devin hydro-mineral deposit, Smolyan region. The deposit occupies an area of about 16 km2, and coincids with the narrow valley of the Devinska River. Hydrochemical methods are applied and chloro-alkaline relations are determined to evaluate the ion exchange and the genesis of the mineral water. The reservoir occurred in a Paleogene tectonic graben filled with breccia-conglomerates, conglomerates, sandstones, and argillites. The mineral water has a composition expressed in equivalent units for cations: Na+ > Mg2+ > Ca2+ > K+, and for anions: (CO3–2+HCO3–) > SO42– > Cl–. The water is of NaHCO3– type, fluorine with a fluoride concentration of 3.7–7.0 mg/L and H2SO3 from 44.62 to 64 mg/L. The TDS content of 247 to 316 mg/l, isothermal to hyperthermal in depth. The regional resources are estimated at 21 l/s and the local resources are estimated at 17.23 l/s. The local geothermal energy of the Devin reservoir reaches 1.212 M J/s.