Preliminary geological, geochemical and numerical study on the first EGS project in Turkey

Abstract

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 FLAC3D plus 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 m 3 and 1 km 2 , respectively, with an injection volume of 122,931 m 3 . 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.

A numerical analysis of the thermohydraulics of an EGS project in Turkey

“…Thus, a ¼ th of the region shown in Figure 1 is defined to be the solution domain. The latter, which is based on the definitions provided in [2] is illustrated in Figure 2, where the different rock zones, dimensions (numbers indicate length in meters) as well as boundary conditions are also indicated.…”

“…In Turkey, in a region near Dikili of the Izmir province, with considerable geothermal properties such as a geothermal gradient of approximately 7K/100m, an EGS project is planned. Hou et al [2] published an investigation on several aspects of this project, including geology and geochemistry.…”

“…In the present analysis, a further numerical investigation of the thermohydraulics of this EGS project is presented, based on the boundary conditions and the numerically obtained hydraulic fracturing data published by Hou et al [2]. The presently applied modelling is similar to that used by Hou et al [2], which was performed by the software FLAC3D [3], which is a code specialized on geotechnical analysis. However, in [2] essentially no details on the mathematical and numerical modelling aspect were provided.…”

“…The presently applied modelling is similar to that used by Hou et al [2], which was performed by the software FLAC3D [3], which is a code specialized on geotechnical analysis. However, in [2] essentially no details on the mathematical and numerical modelling aspect were provided. In the present analysis, modelling details are provided and discussed.…”

Subsurface energy systems in China: production, storage and conversion

“…They found that coastal areas might lower potential due to saltwater intrusion problems. Hou et al (2015b) enhanced geothermal system projects in Turkey, which is being implemented at the license area of SDS Energy Incorporation in Dikili of the İzmir province which has remarkable high thermal gradient of about 70°C/km. Extensive geological, paleoseismic, geophysical and geochemical studies, paleo-stress measurements as well as modeling of hydraulic fracturing and geothermal energy production have been conducted in this area within the scope of this project.…”