Geothermal Potential of the Yanbu Basin in Saudi Arabia: Insights from Reservoir Modeling and Simulations

Abstract In line with Saudi Arabia's commitment to reach net-zero emissions by 2060, the country is actively exploring its geothermal potential, with most planned initiatives focusing on the pre-rift basement formations and geothermal provinces of the Arabian Shield. However, one of the limitations of targeting basement rocks is that they tend to have very low permeabilities, in many cases requiring to implement hydraulic fracturing to enhance connectivity. This work aims to evaluate the potential of producing geothermal energy from porous syn-rift basins’ sediments through reservoir static and dynamic modeling. The methodology involves constructing a representative 3D geological model of the Al-Wajh Formation, utilizing basin and well data, along with information from analogous geological Formations. The workflow incorporates seismic data, well-logs, structural maps, and petrophysical data to create a 3D representation of the geological Formation. A methodology is introduced here to estimate porosity reduction caused by compaction for the deepest parts of the basins where temperatures tend to increase and where, in many cases, no data is available, allowing to estimate the potential production rates for these high temperature and low permeability zones. By integrating this model with numerical simulations, we provide an understanding of the potential rates and temperatures achievable in these types of basins together with the potential thermal power and electric power that could be produced. Our results indicate that water production rates of around 80 liters/second with temperatures of around 120°C can be achieved from a single production well on the basin and this rate can later be achieved on injectors where the water is re-injected into the reservoir once heat has been extracted to maintain reservoir pressure. Reservoir extension and lateral continuity are key parameters that will control well spacing and positioning. For cases where the reservoir lateral extension is large, a bigger well spacing can be used to position producers at higher depths where temperatures are higher, while injectors can be placed on shallower sections where permeability can be higher and reservoir pressure is lower. This will also allow for longer reservoir life, longer temperature break through times, and proper wastewater disposal. This study presents novel insights into the potential and effectiveness of producing geothermal energy from sedimentary rocks present on Rift Basins in Saudi Arabia. It also presents a workflow that estimates porosity reduction on the deepest parts of the Yanbu Basin based on well log data obtained from shallower wells. The findings provide valuable guidance for potential geothermal projects in Saudi Arabia, supporting the country's climate change mitigation goals.