Browsing by Author "Kirste, D"

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    Impure CO2 storage reactions of sandstone, mudstone and carbonate cemented cores: xxperimental CO2 SO2 NOX O2 reaction metal mobilisation and fate
    (Elsevier, 2023-09-01) Pearce, JK; Dawson, GW; Brink, F; Southam, G; Paterson, DJ; Hall, N; Heath, R; Greer, D; Kirste, D; Golding, SD
    CO2 geological storage can be part of the solution to reduce carbon emissions to the atmosphere. An understanding of the geochemical processes occurring during CO2 storage is needed to reduce risk. Drill cores from a low salinity reservoir site proposed for CO2 storage, and the overlying and underlying formations, were characterised for minerals by QEMSCAN, total metals and porosity. Elements including Li, Ba, Sr, K, Mg, V, Zn, REE, Fe, Pb, P, and S were relatively elevated in the Moolayember Formation underlying the reservoir. Synchrotron XFM showed the main host of Mn was siderite, with Rb in K-feldspar, Zn and Cu in sphalerite and chalcopyrite, and As in pyrite in coal pores associated with coal laminations. Drill cores are reacted at reservoir conditions with synthetic formation water and an impure CO2 stream composition of CO2-SOx-NOx-O2 expected to be injected at the site. Elements released were dependant on mineral content, with quartz rich reservoir, lower Precipice Sandstone core reactions resulting in dissolution of trace carbonates, alteration of sulphides and monazite, and variable elevated dissolved Pb, and U. Dissolved Co, Ni, Ca, Zn, Li, Rb, and U were released at relatively elevated concentrations from the mudstone. For carbonate cemented upper Precipice Sandstone or Moolayember Formation core strong dissolution of calcite and ankerite, with corrosion of siderite, Fe-rich chlorite, and sulphides or monazite were observed after reaction. Dissolved elements including Ca, Mg, Mn, Sr, and Ba increased in experiments from the reaction of calcite, siderite, and ankerite. Generally dissolved Fe, Pb, Cr, Cu, Co etc. increased from dissolution, and subsequently decreased in concentration with adsorption and precipitation processes. The fast mobilisation of elements including Fe and Pb are consistent with the release of metals from carbonate dissolution and desorption. The presence of O2 and NOX in the gas stream results in Fe-(oxyhydr)oxide precipitation especially where Fe has been rapidly mobilised from dissolution of siderite and Fe-chlorite. This acts as a sink for Fe and provides new adsorption sites for sequestering a proportion of the trace metals. These processes are applicable to other CO2 storage sites and potential leakage indicators in overlying drinking water aquifers. The findings are also more broadly applicable to subsurface energy storage such as compressed air renewable energy storage, CO2 enhanced recovery, geothermal, natural gas or hydrogen storage. © 2023 The Authors. Published by Elsevier B.V. - Open Access CC-BY.
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    Metal Mobilization From CO2 Storage Cap-Rocks: Experimental Reactions With Pure CO2 or CO2 SO2 NO
    (Frontiers, 2022-07-14) Pearce, JK; Dawson, GW; Southam, G; Paterson, D; Kirste, D; Golding, SD
    CO2 geological storage will be needed as part of the transition to lower greenhouse gas emissions. During CO2 storage, the mobilization of metals from minerals to formation water via CO2 water rock reactions may be a concern for water quality. The sources, behavior, and fate of metals, however, are not well understood. Metals in minerals of calcite cemented sandstone, feldspar-rich sandstone, and ironstone seal drill cores from a target storage site were characterized. The cores were reacted with low-salinity water and pure supercritical CO2 or impure CO2 with SO2 and nitric oxide (NO), under reservoir conditions. Calcite cemented core underwent calcite dissolution with chlorite, plagioclase, and sulfide alteration. The highest concentrations of calcium and manganese were released in the reaction of calcite cemented sandstone seal, with the lowest mobilized arsenic concentration. Pure CO2 reaction of the feldspar-rich sandstone seal resulted in calcite dissolution, with plagioclase, chlorite, kaolinite, illite, and sulfides corroded. Impure CO2 reaction of the feldspar-rich sandstone led to additional corrosion of apatite, pyrite, and sphalerite cements. Generally, dissolved iron, lead, zinc, and arsenic were released and then re-precipitated in oxide minerals or adsorbed. Calcium, manganese, and strontium were released primarily from calcite cement dissolution. Plagioclase corrosion was a second source of dissolved strontium, and chlorite dissolution a second source of manganese. Although sulfides contained higher concentrations of metals, the higher reactivity of carbonates meant that the latter were the main sources contributing to dissolved metal concentrations. The mineral content of the seal cores, and the injected gas mixture, had an impact on the type and concentration of metals released. The ubiquitous presence of carbonate minerals means that this study is applicable to understanding the potential risk factors for water quality changes, and the mobilization and fate of environmentally regulated metals, in both CO2 storage complexes and overlying drinking water aquifers worldwide. Copyright © 2022 Pearce, Dawson, Southam, Paterson, Kirste and Golding. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).