Assessing Seferihisar-İzmir (Türkiye) geothermal energy prospects through marine seismic and field geology data modelling

Abstract

Seferihisar (Izmir) is one of the most significant geothermal regions in the Aegean of Western Anatolia, Türkiye, due to its high geothermal gradient, extensive fault systems, and unique interaction between marine and meteoric waters that create distinct geothermal reservoirs. This study evaluates the geothermal potential and geological characteristics of the Seferihisar area by integrating marine seismic data with onshore geological observations. Specifically, this study combines: (i) geological and geochemical data from geothermal wells along the Tuzla Fault, (ii) high-resolution multichannel seismic reflection data from the Sigacik and Kusadasi Bays, and (iii) correlated onshore and offshore geological and geophysical datasets to develop a 2D conceptual cross-section and a 3D fault model.

Geochemical analyses, including water geochemistry, XRF, and isotope studies, reveal that geothermal fluids in the region originate from a mix of meteoric and marine sources. Chloride concentrations in geothermal wells reach approximately ranging from 11,692 to 12,000 ppm, confirming significant seawater intrusion, while geothermometers estimate reservoir temperatures in the range of 220–280 °C. Isotopic data, such as ³He/⁴He ratios (∼0.9 Ra), suggest minor mantle involvement, and ⁴⁰Ar/³⁶Ar ratios ranging 301 that indicate crustal contributions to the geothermal fluids. These isotopic signatures provide critical insights into the sources and circulation dynamics of geothermal systems.

Through integrated 2D conceptual cross-sections and 3D fault modeling, the study identifies the marine extension of the Tuzla Fault and its role in fluid dynamics, including up-flow and out-flow processes. The fault's continuities are linked to geothermal gradients and active fluid pathways, making the Tuzla Fault a critical target for geothermal exploration. The harmonized models suggest three potential drilling sites with high thermal gradients and fault-controlled fluid flow, optimizing the exploration strategy. Scaling and corrosion challenges in production wells are addressed through the application of inhibitors, which are integral to ensuring sustainable operation and long-term system performance.

These multidisciplinary findings provide likely actionable insights into optimizing resource extraction, reducing environmental impact, and improving the long-term performance of geothermal systems. The study supports sustainable geothermal energy development in the Seferihisar region by addressing production challenges and guiding effective resource management.