Joint Use of Electromagnetic Induction and Magnetic Techniques for Subsurface Imaging at Ain Sokhna–Galala Sector, Gulf-of-Suez, Egypt

Abstract

In this study, a regional prospection using aeromagnetic data of Aero-Service, (1984) was performed firstly to give a general overview on the deep- and shallow-seated structures of the study area. Since the probabilities of geothermal source occurrences increase at sites with high magnetic anomalies and several deep-seated faults, then two sites were selected for detailed studies with ground magnetic and one dimension magnetotelluric (1D MT). The results of magnetic interpretation show that both sites have many deep-seated faults, high magnetic anomalies, and shallow depths to basement rocks. Meanwhile, the one dimension (1D) resistivity model at site (1) shows low resistivities at zones 40 m to 50 m, 150 m to 350 m and 650 to 850 which may reach deeper zone, which may indicate geothermal reservoir. At site (2), (1D) resistivity model shows high resistivity up to 2500 Ohm.m at large depths, from 400 m to more than 7000 m. This high resistivity indicates basement uplift with the absence of underground water, which might be an indication of hot dry rock (HDR) geothermal system. Such systems may be exploited using Enhanced Geothermal System (EGS) technology. In addition to resistivity and magnetic evidences, site of the study area is adjacent to the Gulf of Suez rift, which is an active geothermal area, as indicated by geothermal surface manifestations, such as Ain Sokhna hot spring. The relatively shallow depth to basement rocks obtained from Euler deconvolution and low surface topography obtained from Digital elevation model (DEM) map (U.S. Geological Survey, 2017), combined with resistivity changes and fault distribution highlight this area as a capable geothermal site.