Assessing geochemical reactivity during CO2 geological storage: an example from the Surat Basin
| Autor: | J K Pearce, G K W Dawson, S D Golding, D Kirste, G Southam, D Paterson, F Brink, V Rudolph |
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| Jazyk: | angličtina |
| Rok vydání: | 2023 |
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| DOI: | 10.5281/zenodo.7980120 |
| Popis: | CO2 storage is part of the transition to lower emissions; however, it necessitates a geochemical assessment of potential site-specific impacts. Injected CO2 will dissolve into formation water and the resulting acidification can induce mineral dissolution and precipitation, alteration of porosity and permeability, or mobilisation of metals to groundwater. Reactivity can depend on several factors including the captured gas stream composition, and mineralogical content. We present a comprehensive assessment methodology with a focus here on understanding metal mobilisation. Drill core samples are characterised for minerals, poro-perm, and for metals via total digestions; sequential extractions; and synchrotron X-ray Fluorescence Microscopy. Drill cores are reacted at reservoir conditions with pure CO2 and the specific greenhouse gas stream, e.g., CO2-SOx-NOx-O2. Kinetic geochemical models are then history matched to experimental data that ultimately are inputs to a reactive transport model. The Surat Basin Precipice Sandstone is undergoing feasibility studies as a CO2 storage reservoir, and an example from a storage site assessment is presented here. The Evergreen Formation is the overlying cap-rock, and the Moolayember Formation underlies the reservoir. The lower Precipice Sandstone is quartz-rich while the upper Precipice Sandstone, and the Evergreen and Moolayember formations are mineralogically diverse with higher feldspar, clay, and carbonate content. Dissolved elements Ca, Mg, Mn, Sr, and Ba increased in experiments from reaction of trace amounts of carbonates. Generally dissolved Fe, Pb, As, Cr, Se increased and subsequently decreased in concentration indicating adsorption and precipitation. Kinetic reaction path modelling demonstrated that carbonate minerals and chlorite are the main minerals reacting. The presence of O2 and rapid Fe mobilisation results in the precipitation of Fe-oxyhydroxides that act as a sink for Fe and provide new adsorption sites for sequestering a proportion of the trace metals. In the longer term, CO2 mineral trapping as ankerite at the reservoir-seal interface additionally traps metals. Open-Access Online Publication: May 29, 2023 |
| Databáze: | OpenAIRE |
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