Reactivity of Mount Simon Sandstone and the Eau Claire Shale Under CO₂ Storage Conditions

Abstract

The Mount Simon sandstone and Eau Claire shale formations are target storage and cap rock formations for the Illinois Basin-Decatur Geologic Carbon Sequestration Project. We reacted rock samples with brine and supercritical CO(2) at 51 °C and 19.5 MPa to access the reactivity of these formations at storage conditions and to address the applicability of using published kinetic and thermodynamic constants to predict geochemical alteration that may occur during storage by quantifying parameter uncertainty against experimental data. Incongruent dissolution of iron-rich clays and formation of secondary clays and amorphous silica will dominate geochemical alterations at this CO(2) storage site in CO(2)-rich brines. The surrogate iron-rich clay in the model required significant adjustments to its thermodynamic constants and inclusion of incongruent reaction terms to capture the change in solution composition under acid CO(2) conditions. This result emphasizes the need for experiments that constrain the conceptual geochemical model, calibrate mean parameter values, and quantify parameter uncertainty in reactive-transport simulations that will be used to estimate long-term CO(2) trapping mechanisms and changes in porosity and permeability.

Experimental Perspectives of Mineral Dissolution and Precipitation due to Carbon Dioxide-Water-Rock Interactions

“…By comparison, clay minerals and feldspars did not react, possibly because the carbonate reactions prevented low pH conditions from being attained. In contrast, experiments by Carroll et al (2013) on sandstone and shale at 51 o C and 19.5 MPa found that Fe-rich clays appear to have dominated the reactions, dissolving incongruently to secondary clays and amorphous silica.…”

“…Most data are for far from equilibrium conditions, but Davis et al (2011) While quartz dissolution rates should be rather slow, Houston et al (2007) reported evidence for silica dissolution into injected seawater during a seawater enhanced oil recovery operation in the Miller Field, UK North Sea, but suggested that it was released from feldspars or other silicate minerals, rather than directly from quartz dissolution. Carroll et al (2013), in a study of reactivity of reservoir and caprocks with CO 2 , even reported amorphous silica precipitation from silica released during clay transformations. Overall, injection of CO 2 into existing formation waters is unlikely to have a significant effect on the amount of silica in solution, although it may lead to silica being redistributed from feldspars to clays.…”

Qualitative and Quantitative Changes of Carbonate Rocks Exposed to SC CO2 (Basque-Cantabrian Basin, Northern Spain)

“…Quartz dissolution is calculated using the Si concentration changes while the amount of illite is evaluated using the amount of K concentration. No precipitations of other clay minerals such as kaolinite are considered here, even if in other recent studies kaolinite precipitation has been considered the most favourable secondary alteration mineral [49][50][51]. Here, we stipulate that without alumino-silicate in the initial rock sample such as albite or microcline, kaolinite precipitation is not expected.…”

Impact of SO2 on Alteration of Reservoir Rock with Ca-Deficient Conditions and Poor Buffering Capacity under a CO2 Geologic Storage Condition

“…This gap may arise from the uncertainties of rate constant, mass fraction of minerals, reactive surface area, and thermodynamic data [35,36]. Nonetheless, we consider that the modeling results are acceptable considering only dissolution/precipitation of the minerals (Table 3).…”