Pore-scale simulations for a Geothermal Reservoir under lithostatic pressure and different tail water injection scenarios
Year: 2025
Type: conference-paper
Abstract: Geothermal energy is a promising renewable energy source, considering the high costs of fossilenergy and the need to reduce greenhouse gases drastically. Being a crucial energy source for the energytransition worldwide, the exploration and development of geothermal resources have become increasinglyimportant. The Dunántúli Group (DG), located in the Hungarian part of the Pannonian Basin, stands out asbeing most promising for geothermal energy production. Currently, over 600 operational wells targeting theDG exist in Hungary. It is proposed to drill 2 injection wells for 1 production well in this reservoir, but only5% of the total wells are used for reinjection purposes. Limited knowledge exists about microscale porestructures and flow properties of this formation, crucial for both, successful water reinjection and forgeothermal energy extraction. Severe clogging processes afflict geothermal wells in this region, shuttingdown injection wells within a short amount of time, causing significant extra costs and delays in progressingHungary´s energy transition.The first part of this study [1] (presented at the 2024 SCA Symposium) investigated selected reservoirsamples from the DG. Classical mineralogical and petrophysical methods, an extensive core-floodingprogram for controlled clogging of artificial and natural core samples, as well as X-ray µ-CT imaging,qualitative and quantitative 3-D image analysis, and pore scale simulations with special focus upon thephysical pore clogging have been utilized. As highlighted, storage properties are favorable, and the porethroats, which control fluid flow, are nearly of the same size as the movable particles within the pore-system.This fact, coupled with smaller particles present in the re-injection fluid, leads to significant and deep-seatedclogging of flow pathways.In the second phase of this ongoing project, we simulated the effects of lithostatic stress and varying injectionpressures on pore geometry and flow properties using digital rock models. Since the permeable part of theDG lacks cementation, or part of the cement has leached out during previous processes, excessive reinjectionpressures may lead to formation compaction, reducing pore throat size and progressively clogging the entireinjection zone. Using our newly developed workflow in GeoDict, we can simulate various reinjectionscenarios, improving the understanding of clogging mechanisms and optimizing tail water reinjectionstrategies. These insights will significantly advance the understanding of fluid transport in the DG andsupport stakeholders in developing more efficient and sustainable reinjection wells.
Authors: Mwendia Njeru, Rita, Halisch, Matthias, Jacob, Arne, Weber, Andreas, Szanyi, János
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W6893405385
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