Assessment of Geothermal Resources at the Al-Lith Area, Kingdom of Saudi Arabia

Abstract

The geothermal resources of the Kingdom of Saudi Arabia are mainly located along the western and southwestern coastal parts. These resources are associated with the main tectonic activities and elements that are prevailing during the opening of the Red Sea and Gulf of Suez rift. The Al- Lith area is one of the most promised geothermal targets, which is located along the western coast of the Red Sea, about 180 km south of Jeddah city. Four main hot springs (Ain A1 Harrah, Bani Hilal, Wadi Markub and Al Darakah) with a surface temperature range from 41oC to 96 oC, are encountered this area and originating from deep-seated highly altered granitic rocks. The aim of this study is investigate the potentiality of these geothermal resources and to detect the subsurface orientation and the structural elements which control the upcoming geothermal water to the surface. Based on the chemical analyses of many water samples collected from the hot springs and their neighbouring wells, a geo-thermometric study is conducted to estimate the heat flow, discharge enthalpy and subsurface temperature. In addition, a 2D electric study is enhanced to detect the shallow subsurface structures and fracture system. Based on the geo-thermometers fair to good subsurface temperature, discharge enthalpy and heat flow values are calculated at these hot springs (105°C - 136°, 170 Kj/Kg - 219 Kj/Kg and 137 mW/M2 - 183 mW/M2). The 2D interpreted electric sections clarified that, a number of near-vertical northwest-southeast and east-west trending faults and fracture elements are effecting the whole geothermal system in the area. Ain A1 Harrah hot spring is found with good geothermal parameters. In terms of its potential reserves, it needs to be further investigated and evaluated in future for possible energy production.