Reevaluation of Geothermal Energy Potential in Damavand Region

Abstract

Damavand region including an elevated stratovolcano and many hot springs surrounding, is one of the most promising areas in Iran for geothermal energy potential. About 31 years ago, the Italian corporation ENEL (Ente Nazionale per lEnergia Elettrica) performed some geological, geochemical and geophysical exploration studies to identify the Damavand region geothermal reservoirs. Studies indicated that the Triassic-Paleozoic sequence constitutes promising geothermal reservoirs and that the Shemshak formation is a good cover (with thickness of about 1000 m). Also the reservoir fluid temperature was estimated at about 150ºC. Finally, upon the results of geophysical surveys (magnetotelluric and thermal survey), an area of about 200 km2 was selected for detailed exploration studies. To perform complementary and updated explorations in the geothermal region of Damavand, this paper considered available information and reevaluated data after the passing of three decades since the studies mentioned above. For this reason, first all available maps were digitized and corrected using satellite data of the region. Then physicochemical characteristics (pH, temperature, flowrate, etc.) of the region hot springs such as Ab-ask, Baidjan and Larijan were reexamined. With the aid of Damavand region satellite images, the distribution condition of altered zones and also the distribution of thermal anomalies were considered and their results compared with the available data. Present evaluations confirmed that the Damavand region weather conditions (especially average annual rainfall) particularly in Ab-ali weather station, had not changed during the time period. Also physicochemical characteristics had not changed noticeably. Examination of thermal infrared images and alteration zones indicated that as suggested by the results of the ENEL experts, Damavand geothermal reservoir is generally and suitably capped by the Shemshak formation in the region. Based upon this evidence, we conclude that the dominant conditions of Damavand geothermal reservoir had not been changed considerably after the passing of three decades. So it is possible to plan and perform detailed exploration studies in the potentially favorable area of the Damavand geothermal region.