Browsing by Author "Zhang, Qin"

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    Evaluation of the potential of glauconite in Western Canadian Sedimentary Basin for large-scale carbon dioxide mineralization
    (Elsevier, 2022-04) Zhang, Qin; Tutolo, Benjam.M.
    Geologic carbon dioxide (CO2) storage is an essential and economical measure to mitigate global climate change. CO2 storage potential in sedimentary reservoirs is commonly passed over in favor of more reactive rock formations, such as basalts, because the latter offer rapid, permanent storage as carbonate minerals while the former are thought to only offer less permanent physical trapping of CO2. Nevertheless, recent research has demonstrated that carbonation reactions in glauconitic sandstones are favorable under realistic reservoir conditions, although the overall availability of glauconite for carbonation has not yet been quantified. Here, we use calculations based on 11,652 well logs to show that glauconitic sandstones offer significant and previously overlooked potential for sedimentary reservoir-based mineral carbonation. Our results demonstrate that hundreds of gigatons of CO2 could be sequestered by carbonating the immense quantity of glauconite underlying Alberta, Canada alone. Importantly, these glauconitic sandstones, and others worldwide, have long been exploited for their favorable hydrocarbon production capacity. Thus, global societies eager to limit greenhouse gas emissions may need to look no further than the reservoirs they are already exploiting. Moreover, because the requisite injection infrastructure is oftentimes still active, glauconitic sandstones may present the highest priority, lowest capital cost substrate for mineral carbonation worldwide.
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    From Greensands to Green Technology: Examination of Carbon Dioxide Storage Potential in Glauconitic Sandstones
    (2022-05) Zhang, Qin; Tutolo, Benjamin; Mayer, Bernhard; Clarkson, Christopher; Hubbard, Stephen; Meyer, Rodolfo; Wilson, Siobhan
    Glauconite is a divalent cation-bearing mineral abundant in sedimentary rocks and hydrocarbon reservoirs worldwide, and it may be important for ongoing efforts to geologically store anthropogenic CO2. Since glauconite naturally contains both Fe(II) and Fe(III) in its mineral structure, it can also be leveraged to constrain paleoenvironmental redox conditions. Nevertheless, because of its complex mineralogy and redox sensitivity, thermodynamic and kinetic properties of glauconite have been difficult to constrain. This thesis has been devoted to fill this significant knowledge gap. Chapter 2 contains a detailed evaluation of the mechanisms through which carbonate minerals naturally replace glauconite during diagenesis of glauconitic sandstones from the Mannville Group in Alberta, Canada. Using a combination of petrological and geochemical analyses, we show that glauconite carbonation is a reduction-facilitated, coupled glauconite recrystallization and siderite precipitation reaction, which is accompanied by a significant reduction of Fe. These results suggest that geochemical conditions, most importantly, temperature, partial pressure of CO2, and fluid redox state were thermodynamically favorable for glauconite carbonation during burial diagenesis of Mannville Group glauconitic sandstones. Chapter 3 quantifies the far-from-equilibrium rates of glauconite dissolution using a novel experimental apparatus specifically designed to explore mineral dissolution kinetics under strictly anaerobic conditions. Steady-state glauconite dissolution rates were measured at varying pH from 1.7 to 11.2 and temperature from 24 to 80 °C. The experimental results show stoichiometric or close-to-stoichiometric glauconite dissolution for Fe, Mg and Si. In comparison to previous studies, we emphasize that the mechanism of glauconite dissolution is determined by redox condition and temperature, and the dissolution rates are pH-dependent in acidic conditions and pH-independent in natural to basic pH. Chapter 4 uses calculations based on 11,652 well logs to show that glauconitic sandstones offer significant and previously overlooked potential for sedimentary reservoir-based mineral carbonation. Our results demonstrate that hundreds of gigatons of CO2 could be sequestered by carbonating the immense quantity of glauconite underlying Alberta, Canada alone. Together, these findings suggest that glauconite had been underestimated both in terms of availability and reactivity, and these new findings provide important insights to re-evaluate CO2 storage in sedimentary basins.
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    Geochemical evaluation of glauconite carbonation during sedimentary diagenesis
    (Elsevier, 2021-05-25) Zhang, Qin; Tutolo, Benjamin
    Glauconite is an authigenic, iron-rich clay mineral that is abundant in greensands formations worldwide. Evidence from these formations suggests that glauconite is commonly diagenetically converted to carbonate minerals such as siderite, ankerite, and ferroan dolomite. This process represents a natural CO2 sink that may provide an e ective mechanism for the engineered mineralization of anthropogenic CO2. To evaluate glauconite carbonation reactions and improve our understanding of glauconite diagenesis, we performed a detailed evaluation of the mechanisms through which carbonate minerals naturally replace glauconite during diagenesis of glauconitic sandstones from the Lower Cretaceous Upper Mannville Group in western Alberta, Canada. Using a combination of optical microscopy and scanning electron imaging, electron microprobe and bulk geochemical analyses, and x-ray fluorescence mapping, we show glauconite carbonation in the Mannville group is an reduction-facilitated, coupled glauconite recrystallization and siderite precipitation reaction. X-ray absorption near-edge spectroscopic mapping and spot analyses demonstrate that this reaction is accompanied by a significant shift in the oxidation state of Fe, from dominantly oxidized in glauconite to reduced in carbonate reaction products. Together, these results suggest that geochemical conditions - most importantly, temperature, partial pressure of CO2, and fluid redox state - were thermodynamically favorable for glauconite carbonation during burial diagenesis of Mannville Group sandstones. Results of thermodynamic models illustrate that, although K-feldspar is favored to precipitate during reductive glauconite dissolution and accompanying Fe-carbonate precipitation, its precipitation is likely kinetically limited, and that an Fe-impoverished glauconite is expected to recrystallize instead. Our findings show that glauconite carbonation is likely a common phenomenon in the subsurface, and thus that glauconite is potentially a significant cation source for mineralizing anthropogenic CO2.