Print Email Facebook Twitter Injection related issues of a doublet system in a sandstone aquifer Title Injection related issues of a doublet system in a sandstone aquifer: A generalized concept to understand and avoid problem sources in geothermal systems Author Markó, Ábel (German Research Centre for Geosciences; Eötvös Loránd University) Mádl-Szőnyi, Judit (Eötvös Loránd University) Brehme, M. (TU Delft Reservoir Engineering; German Research Centre for Geosciences) Date 2021 Abstract This study proposes a concept and presents a workflow to examine potential reasons for low injectivity of sandstone aquifers. Injection related problems are a major challenge for the sustainable utilization of geothermal waters. In order to completely understand and avoid the geothermal reinjection problems, potential problem sources acting on different scales should be taken into consideration. Thus, in the workflow, possible problem sources are considered on regional, reservoir and local scale and categorized into 1) effect of regional hydraulics (potential presence of overpressure and upward flow) 2) inadequate reservoir performance (limited extent, low permeability and performance) and 3) local clogging processes (particle migration, mineral precipitation, microbial activity). Hydraulic conditions are characterized by defining the pressure regime and the direction of vertical driving forces. The reservoir properties are given by determining the grain size and the size of the reservoir layers, as well as the permeability and the transmissivity of the reservoir and the capacity of the injector. Physical, chemical, and biological clogging processes are investigated by specifying the rock properties and determining particle content of the fluid; by analysing the type, probability and amount of the scaling and estimating the potential for corrosion; and by evaluating the possibility of biofilm formation. The concept and the workflow were first tested on a geothermal site (Mezőberény, SE Hungary, installed in 2012) that had to stop operation because of unsuccessful reinjection. The low injectivity of the well is a consequence of several separate problems and their interaction: Reservoir properties are insufficient due to low permeability and transmissivity of the reservoir and the limited vertical and horizontal extension of the sandstone bodies. Precipitation of carbonates, iron and manganese minerals is predicted in hydrogeochemical models and observed in solid phase analysis. Microbial material is produced from the particularly high organic content of the produced thermal water. Injection problems due to hydraulic effects are not expected since the regional pressure regime is slightly subhydrostatic. In summary, reservoir properties determine a low injectivity, which is further decreased to a critical level by the clogging processes. The proposed generalized concept guides a detailed reservoir and geothermal system analysis which is essential for a sustainable geothermal operation. Subject Geothermal reinjectionInjection problemRisk analysisSandstone aquiferThermal waterWorkflow To reference this document use: http://resolver.tudelft.nl/uuid:97697933-5991-4092-ae97-3b01370d52cf DOI https://doi.org/10.1016/j.geothermics.2021.102234 ISSN 0375-6505 Source Geothermics, 97 Part of collection Institutional Repository Document type journal article Rights © 2021 Ábel Markó, Judit Mádl-Szőnyi, M. Brehme Files PDF 1_s2.0_S0375650521001917_main.pdf 4.55 MB Close viewer /islandora/object/uuid:97697933-5991-4092-ae97-3b01370d52cf/datastream/OBJ/view