1,721,014 research outputs found
Thermo-hydro-mechanical modelling study of heat extraction and flow processes in enhanced geothermal systems
No full textOpen-Access-Publikationsfonds 202
Hydrogeochemical modeling of mineral alterations following CO2 injection
No full textAlterations of the mineral phase of deep reservoirs are desired as a process for carbon capture and storage, driven by changes in fluid composition due to CO2 injection. Underlying concepts for hydrogeochemical modeling are implemented in the codes PHREEQC and MIN3P, adapted to cope with pressures and temperatures in deep reservoirs with up to 300 °C and 1000 atm. Simulations were performed using field data from the Heletz, pilot CO2 injection site (Israel), located at the edge of a decommissioned oil field in a sandstone formation, showing a shift of saturation index (SI) and dissolution/precipitation reactions of silicates and carbonates subsequent to injection of CO2. Alterations of the mineral phase with time were largest in the sequence Ankerite > Dolomite > Calcite > Magnesite, and for the mineral Dawsonite during early stages when only Na+ is present in high ionic concentrations. The uncertainty of mineral saturation, a consequence of the variability of water chemical composition and the database records, was investigated by principal component analysis and sensitivity coefficients. A large variability in the occurrence of Dolomite can be explained by salinity variations and the inverse dependency of total amount of carbon mineralization between Pitzer and Debye-Hückel/Davies (D-H/D) based activity computation.</p
Development of a numerical workflow based on μ-CT imaging for the determination of capillary pressure–saturation-specific interfacial area relationship in 2-phase flow pore-scale porous-media systems: a case study on Heletz sandstone
Full text linkIn this case study, we present the implementation of a finite element method (FEM)-based numerical pore-scale model that is able to track and quantify the propagating fluid–fluid interfacial area on highly complex micro-computed tomography (μ-CT)-obtained geometries. Special focus is drawn to the relationship between reservoir-specific capillary pressure (pc), wetting phase saturation (Sw) and interfacial area (awn). The basis of this approach is high-resolution μ-CT images representing the geometrical characteristics of a georeservoir sample. The successfully validated 2-phase flow model is based on the Navier–Stokes equations, including the surface tension force, in order to consider capillary effects for the computation of flow and the phase-field method for the emulation of a sharp fluid–fluid interface.
In combination with specialized software packages, a complex high-resolution modelling domain can be obtained. A numerical workflow based on representative elementary volume (REV)-scale pore-size distributions is introduced. This workflow aims at the successive modification of model and model set-up for simulating, such as a type of 2-phase problem on asymmetric μ-CT-based model domains. The geometrical complexity is gradually increased, starting from idealized pore geometries until complex μ-CT-based pore network domains, whereas all domains represent geostatistics of the REV-scale core sample pore-size distribution. Finally, the model can be applied to a complex μ-CT-based model domain and the pc–Sw–awn relationship can be computed
A snapshot sample on how COVID-19 impacted and holds up a mirror to European water education
No full textCOVID-19 caused many disruptions, not only in society, but also in university education, including in hydrology and water-related sciences. Taking part in an academic teaching training course at Uppsala University during COVID-19, we got curious about how COVID-19 might have impacted European water education. Consequently, we chose to investigate this aspect in the mandatory project of the course by conducting an online survey. In this paper, we communicate the results of the survey and reflect (hold up a mirror to water education) on how the teaching of hydrology and water-related sciences changed due to COVID-19. The answers of 28 respondents, working in the field of hydrology at different universities across Europe, showed that in the pre-COVID-19 classroom lectures, laboratory work and fieldwork were commonly used teaching formats in courses with 10 to more than 40 students. These results agreed with those found in the literature. The occurrence of COVID-19 forced hydrological education to suddenly move from classroom to online teaching, which was possible thanks to the available digital tools and technical infrastructure. The practiced online teaching format remained lectures. Most of the respondents (>40 %) reported not using classroom assessment techniques to gauge the students' performances. In addition, a loss of human interaction in the online environment was noticeable. Hence, whether students reached their learning outcomes during distance teaching was largely unknown. The most affected learning activities were the ones that could not be moved to online teaching, such as laboratory work and fieldwork. As a result, comprehensive hydrological knowledge might be missing for at least several cohorts of hydrologists. In this way, COVID-19 caused a secondary effect on society which needs skills in solving future challenges such as water management in a changing climate. Next to negative aspects, we observed positive COVID-19 aspects; for example, the hydrology community explored novel teaching formats and shared teaching material and experiences online. COVID-19 forced hydrology teachers to explore, improvise, and be creative to continue teaching. Hydrology can use this experience to learn from and modernize hydrology education by developing a lesson design suited for the online environment, including best practices and making practical and “exotic” non-traditional teaching formats accessible to all hydrology and water students
Optimization of Well Configuration for EGS Performance with Multi-Dimensional Two-Phase Flow Modelling
No full textModeling fate and transport of hydraulic fracturing fluid in the presence of abandoned wells
No full textInfluences of directional aperture heterogeneity on the performances of two-phase enhanced geothermal system considering the CO2 buoyant force
No full texthttp://dx.doi.org/10.13039/501100002347 Bundesministerium für Bildung und Forschunghttp://dx.doi.org/10.13039/501100010571 Bundesministerium fur Bildung und Forschung Dienststelle Berli
Thermo-sensitive tracer technology to monitor the movement of thermal front in geothermal energy production
No full texthttp://dx.doi.org/10.13039/501100002347 Federal Ministry of Education and Research Bonn Offic
Effects of fracture aperture distribution on the performances of the enhanced geothermal system using supercritical CO2 as working fluid
No full texthttp://dx.doi.org/10.13039/501100004543 China Scholarship Counci
Study on the influence of randomly distributed fracture aperture in a fracture network on heat production from an enhanced geothermal system (EGS)
No full textChina Scholarship CouncilChina Scholarship Counci
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