Systematic and Multidisciplinary Exploration in the Lithotopos - Iraklia Low Enthalpy Geothermal Field (Macedonia, Northern Greece)
Apostolos ARVANITIS, Konstantina KAVOURI, Georgios VOUGIOUKALAKIS, Petros KARMIS, Markos XENAKIS, Ilias KOUFOGIANNIS, Vassiliki SOMATARIDOU, Panagiotis VAKALOPOULOS, Dimitrios EXIOGLOU
The Lithotopos-Iraklia low enthalpy geothermal field is located in the NW part of the Strymon basin (Macedonia, Northern Greece) between Lake Kerkini and the small city of Iraklia. Ten exploration boreholes (Li-1 to Li-10) and one large-diameter exploration well (Li-1P) were drilled by I.G.M.E.(Institute of Geology and Mineral Exploration) in the period 1982-1983 and 2000 respectively, demarcating an area of about 45 km2, which has been officially characterized as probable low temperature geothermal field. The temperatures of 40-62oC were measured at depths of 200-433m. During 2013-2018, a systematic and multidisciplinary geothermal exploration was conducted by I.G.M.E. This geothermal project was divided into two main stages: (I) At first, a preliminary study was performed aiming at the definition of the locations of new production wells and included (i) collection and critical review of the existing geological, structural and drilling data, (ii) water temperature measurements, (iii) water sample collection and chemical analysis, (iv) soil gas (CO2 and Rn) measurements and (v) geophysical surveys (TEM). (II) The appraisal study was the next development phase and included (i) drilling activities and construction of four production wells, (ii) borehole temperature measurements, (iii) assessment of thermal conditions, (iv) logging surveys, (v) pumping tests, (vi) determination of production capacity of wells, (vii) evaluation of hydraulic characteristics of the geothermal reservoir, (viii) distribution of productive aquifers, (ix) temperature and pressure distribution, (x) reservoir engineering and modeling approach, (xi) delineation of production and potential re-injection areas, (xii) water and gas sampling and analysis, (xiii) fluid chemistry and geothermometry and (xiv) evaluation of scaling and corrosion potential of fluids. The obtained data is used to confirm the existence of geothermal resources suitable for future exploitation. Geothermal waters of up to 75oC are hosted in sands, sandstones, conglomerates, breccias and fractured metamorphic basement. The new production wells, 352.5-519.5m deep, yield waters of 37.5-74.5οC. The flow rates range between 5 and 80 m3/h depending on lithology, aquifer properties and screen depths. The produced geothermal waters with TDS values of 0.55-1.32 g/l belong to the Na-HCO3 type. The total installed thermal capacity from the existing production wells is estimated to be 4.47 MWt.
|        Topic: Exploration||Paper Number: 11125|