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| Titel |
Interactions between scCO2 and scCO2-SO2, formation fluids and rock forming minerals: an experimental approach under in-situ conditions of potential geological storages |
| VerfasserIn |
Franziska Wilke, Monica Vásquez Parra, Jörg Erzinger |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250054498
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| Zusammenfassung |
| The storage of CO2 in the deep underground is regarded to be one possibility to reduce the release of anthropogenic CO2 in the atmosphere. Therefore, experiments have been performed to investigate the interactions between CO2 and concomitant gases with potential reservoir rocks considering both the injection and storage phases of the sequestration process. With respect to the composition of CO2 captured industrially from coal-fired power plants using the Oxyfuel technology contaminants like SO2 (plus possibly NOX and O2) were chosen to investigate chemical corrosion of rock-forming minerals with impure supercritical CO2 (scCO2) at possible storage conditions of >73.7 bar and >31°C. Co-injection of SO2 (and NOX and O2) has been expected to cause a stronger brine acidification of the deep saline aquifers than CO2 alone. Experiments up to 1000h have been performed with 3n NaCl solution, 12 natural mineral concentrates and pure scCO2 or scCO2+SO2 (99.5+0.5vol-%; “impure scCO2”) gas mixture. The brine composition reflects the average salinity of deep formation waters of the North German Basin. To increase the reaction rates all minerals were ground and the reagents agitated either by stirring or shaking in 1L-reaction autoclaves. The autoclaves consist of Hastelloy™ or ferromagnetic stainless steel fully coated with PTFE to avoid contact between metal and reaction agents. In average, we used 15 g of solids and 700 ml liquid. The autoclaves were pressurised up to 100 bar with CO2 or CO2+SO2 mixture. Before, during and after the experiments reaction fluids were sampled and analysed by ICP-MS and IC. Solid phases were characterised by XRF, ICP-MS, and EMPA before and after the experiment and pH, pressure and temperature are monitored. Interactions with pure scCO2 show slight changes in the mineral composition of albite as it gained in a not yet identified carbonate phase that might be dawsonite. The compositions of e.g. clay minerals, microcline, anhydrite and micas remain nearly unchanged at a min. pH of 4. Carbonates, like calcite, dolomite and siderite were corroded at min. pH of 7-8. Experiments using scCO2+SO2 have a lower pH than using scCO2 alone, at which those with silicates or anhydrite have a lower pH (2-3) than experiments with carbonates (>5). Fluid-mineral interactions are generally stronger using impure scCO2+SO2 and reaction fluids contain much higher amounts of cations, especially Fe, Si and Al when silicates were studied. However, the intensity and rate of reaction is controlled by the availability of SO2. |
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