Deep heat source detection using the magnetotelluric method and geothermal assessment of the Farafra Oasis, Western Desert, Egypt

Abstract

Nonrenewable hydrocarbon energy sources provide the bulk of Egypt's energy. However, the nation needs to diversify its energy portfolio and use conventional and renewable energy in tandem to ensure its long-term economic growth; therefore, harvesting untapped geothermal resources might help Egypt meet its energy needs in a sustainable and effective manner. The Farafra Oasis is located in the midst of Egypt's Western Desert and has been selected as the focal point for sustainable long-term development in the Western Desert.Using a magnetotelluric (MT) survey, a deep exploration of the Farafra region has been conducted to explore the underlying geological state and, as a result, explain the origin of several thermal wells around the oasis. None of the prior studies reached the necessary depths to offer information on the surface of deep igneous rocks, which may be the source of heat in the study area. Two field excursions were conducted to measure 19 stations along a line crossing the Farafra Oasis and extending more than 130 km. The MT instrument measured periods greater than 1000 s to gather low-frequency data with great efficiency.On the basis of 2D inversion of MT data, a mathematical model of the Farafra region's geothermal system was built to visualize and characterize the heat sources underneath the Farafra Oasis. It was shown that the existence of a high-temperature pluton at considerable depth is the primary cause of the temperature rise in the aquifer under the Farafra Oasis, as the water mass builds up on top of plutonic rocks and flows upwards via fractures and faults.