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Ankara, Turkey

Eker A.M.,SDS Energy Inc. | Kockar M.K.,Gazi University | Akgun H.,Middle East Technical University
Engineering Geology | Year: 2015

This study mainly concentrates on the determination of site effects for the Plio-Quaternary and especially alluvial soils of the Çubuk district and its close vicinity in Ankara, Turkey. In the study area, particularly in the vicinity of the asymmetric graben that has formed due to the tectonic activities along the NE-SW trending normal faults, a microtremor survey was implemented to identify the local site response under a possible seismic event. The results were compared and correlated by using passive and active surface wave measurements, engineering geological and geotechnical deep borehole logs along with information on local geology and geological tectonic setting. Regarding the microtremor results, larger fundamental periods were acquired than expected over the area and the effect of the tectonic deformation on the stiffness of the soils was also observed at either the H/V curves or the shear wave velocity profiles. The results have demonstrated that geotechnical information down to a depth of 30. m may not be compared with the H/V parameters. The H/V amplitudes were not always accompanied with the higher periods in the Quaternary sediments. This could be due to the basin and basin edge effects observed particularly at the center and boundary of the basin, respectively. Additionally, the microtremor survey showed that the spectral ratio amplitudes derived by the H/V ratio are debatable and are not a direct indicator of local soil behavior under a seismic excitation. © 2015 Elsevier B.V. Source

Hou Z.,Clausthal University of Technology | Sen O.,SDS Energy Inc. | Eker A.M.,SDS Energy Inc. | Yal G.P.,SDS Energy Inc. | Cambazoglu S.,SDS Energy Inc.
Environmental Earth Sciences | Year: 2015

Geothermal energy is attracting more and more attention due to its large capacity and lack of dependency on the weather. Currently, many countries have planned enhanced geothermal system (EGS) projects. In this paper the first EGS project in Turkey, which is being implemented at the license area of SDS Energy Inc., in Dikili of the İzmir province, is introduced. Extensive geological, paleostress (279 fault-slip data from 33 locations), geophysical (magnetotelluric and vertical electrical sounding at 80 and 129 locations, respectively) and geochemical studies as well as paleostress measurements have been conducted in this area within the scope of this project. In the light of all these studies, it has been determined that the Dikili region is remarkable in terms of its high thermal gradient of about 7 °C/100 m. The geothermal reservoir formation “the Kozak granodiorite” is a homogeneous, crystalline volcanic rock mass with high radiogenic heat production, and suitable for an EGS application. The analysis shows that the dominating fault system is normal, and the corresponding primary stress regime is extensional. Based on the geological, geophysical surveys and the estimated in situ stresses, numerical studies were carried out to assess the results of the hydraulic fracturing and geothermal energy production using the numerical codes FLAC3Dplus and TOUGH2MP, respectively, in the area A of the Dikili site. The simulation results show that the stimulated reservoir volume and area could reach 44.5 million m3 and 1 km2, respectively, with an injection volume of 122,931 m3. Assuming the fractured zone has a height of 1000 m and a half-length of 1200 m (the distance between injection and production wells being 1000 m), an average overall geothermal capacity of 83.7 MWth in 20 years could be reached with an injection rate of 250 l/s. The injection strategy and design parameters of the reservoir stimulation and geothermal production will be further optimized with the project running. © 2015, Springer-Verlag Berlin Heidelberg. Source

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