Gravity modeling of a prospective geothermal field of a hot spring in Western Saudi Arabia

Abstract

The present study focuses on the geothermally prospective area of Wadi Al Lith (Western Saudi Arabia), which is expressed by the presence of hot springs. With a surface temperature that exceeds 80 °C, the Ain Al Harrah hot spring presents the most promising area for geothermal energy production. The Wadi Al Lith prospective geothermal field was generated by tectonic processes involved in the evolution of the Red Sea Rift. A land gravity survey of the area around the hot spring was conducted to develop a comprehensive model of the subsurface. The data were processed using the standard correction methods to construct the Bouguer anomaly map of the area, and the reservoir's 2D and 3D subsurface geometry was estimated. Our analysis revealed low gravity values at the hot spring site and high values in areas where the basement rocks are exposed. The 2D and 3D models were constrained and interpreted using available information from a shallow borehole and other geophysical methods (MT, TEM, and refraction seismic) that have been conducted in the area. The models suggest the possible existence of a geothermal reservoir by highlighting the tectonic structures and the fracture systems that facilitate the transport of thermal fluids to the surface. By reconstructing a detailed subsurface model of the Ain Al Harrah hot spring's surrounding area, the study highlights the potential of the Wadi Al Lith for renewable energy production. An exploratory and production drilling program is suggested, based on the interpretation of the geophysical data.