Geoejector: Extracting geothermal fluid from a low-pressure geothermal well
Author: Jeffrey Macatangay Andal
Year: 2023
Supervisors: Guðmundur Kristjánsson, María Sigríður Guðjónsdóttir, Egill Juliusson
Abstract:
To utilize a low-pressure and low-enthalpy well, a subsonic ejector system (referred to as subsonic geoejector) was developed and tested at the Theistareykir Geothermal Field in 2020 and 2021. The system connected a low-pressure geothermal well to a nearby high-pressure well to induce flow from the low-pressure well under otherwise unfavorable pressure. The subsonic geoejector has similar working principle as an industrial ejector used in many industries. However, unlike traditional ejectors, it is faced with challenges involving two-phase geothermal fluids and highly variable inflow conditions. From analysis with an analytical and numerical model of the subsonic geoejector, it was found that it cannot accelerate the high-pressure fluid enough to create an underpressure that will induce flow from the low-pressure well under real operating conditions. To address this problem, this paper will introduce a supersonic geoejector that was designed to meet the operational requirement for power production and analyzed with an analytical and numerical model. The result of the models are promising, and it is found that the new setup could potentially increase the pressure of geothermal fluid from low-pressure well sufficiently or up to 2.4 bar, which would add up to 0.8 MWe for power generation.