|dc.description.abstract||The geological storage of CO2 is a means that stores CO2 in deep porous rocks with CO2 trapped by physical and chemical processes. Injected CO2 may react with minerals in the host rocks, resulting in mineral dissolution or mineralization. In order to understand possible chemical reactions between CO2 and rocks, one needs to characterize the mineral contents of CO2 reservoirs and caprocks. Mineralogy of reservoir and seal rocks are characterized by petrographic studies and X-ray diffraction (XRD) analyses. Studied samples are collected from three stratigraphic sections of Ming-Der Dam, Tachiachi and Tsaohuchi, in central Taiwan. Those samples are from six stratigraphic units of Tungkeng Formation, Sangfuchi Sandstone, Kuantaoshan Sandstone, Shihliufen Shale, Yutenping Sandstone, Chinshui Shale and Cholan Formation, in a stratigraphically ascending order.
Predominant minerals in sandstone are quartz, feldspar and rock fragments. According to petrographic analysis, Many pores in sandstones are filled with cements for Kuantaoshan Sandstone, Yutenping Sandstone and lower part of Cholan Formation, but more open pores are found in the Tungkeng Formation, Sangfuchi Sandstone, lower part of the Kuantaoshan Sandstone and middle part of the Yutenping Sandstone. The results of whole rock XRD analyses show that main minerals in samples are quartz, orthoclase, microcline, plagioclase, calcite, dolomite, illite, kaolinite and chlorite. Dominant clay mineral is illite except for the Sangfuchi Sandstone. Chlorite is also common found in studied samples. Kaolinite is the most abundant clay mineral in Tungkeng Formation and Sangfuchi Sandstone. Smectite and mixed layered minerals are rarely found in whole studied samples.
Results of this study shows that there are high porosity for the Tungkeng Formation, Sangfuchi Sandstone, lower part of th Kuantaoshan Sandstone and middle part of the Yutenping Sandstone. They may serve as good CO2 reservoirs. Chinshui Shale may serves as main caprocks. Sandstones of the Tungkeng Formation, Sangfuchi Sandstone and middle part of the Yutenping Sandstone consist of minor amount of carbonate minerals, serving as stable reservoirs for CO2 geosequestration.
Predominant minerals in sandstones of the Tungkeng Formation and Sangfuchi Sandstone are quartz and feldspar with rare rock fragments, indicating that tectonic setting of source terranes are of South China continental block affinity. Abundant rock fragments in the Cholan Formation indicate that sediments were derived from Taiwan mountain belt.||en_US|