Extraction of geothermal fluids from enhanced geothermal systems: optimization of a gas lift sparger

Abstract

This study explores the application of a gas lift system for extracting geothermal fluids from enhanced geothermal systems (EGS) with reservoir temperatures exceeding 400∘C (752∘F) and depths up to 15 km (9.3 mi). Using a validated numerical pressure gradient model, 15 different 3D-printed gas sparger designs were tested through over 100 scaled experiments. The investigation focused on critical parameters, including the submergence ratio, venturi area, orifice size, and orifice count. The optimal sparger featured a venturi area of 95% and 51 orifices, which increased the flow rate by 24% and efficiency by 30% compared to a baseline design without a sparger. Although partial blockage of orifices reduced performance, it did not critically affect system operation, demonstrating the sparger's robustness. Numerical extrapolation to a 4000 ft deep EGS well indicated that optimized spargers could increase the pressure gradient by 10% on average, resulting in a 30% boost in water production at the same wellhead pressure and injection flow rate as a setup without a sparger. These results highlight the potential for gas lift systems with optimized spargers as an efficient, low-maintenance alternative to conventional pumps in harsh EGS geothermal environments.