## 1 Introduction
### Shale Interactions (Multi-Mineral)
The particular mercury contact angle used was not reported, nor was any comparison made between mercury porosimetry data and nitrogen desorption, which should be equivalent invasion percolation processes. The surface area (SA) was found to decrease following treatment in all cases. However, as seen in Figure 4, different pore size ranges reacted differently after treatment. [PERSON] et al. [25] suggested that carbonate dissolution and precipitation are accountable for the opening of the micropores, and this is consistent with the 30% rise in porosity seen in FE-SEM analysis. The decrease in nanopores may be due to an aggregation of clay and organic features and precipitating particles. Figure 4: Pore size distribution analyses of the outcrop and production Utica shale samples: (**A**) 0.7 nm to 10 nm (from N\({}_{2}\) sorption isotherms) (**B**) 0.003 \(\upmu\)m to 350 \(\upmu\)m (from Hg porosimetry). Insets show corresponding pore volume distributions of the unexposed, CO\({}_{2}\)-exposed, and CO\({}_{2}\) + H\({}_{2}\)O\(-\) exposed samples for the 0.7 nm to 2 nm and 5 \(\upmu\)m to 10 \(\upmu\)m pore diameter ranges. Uncertainties are within \(\pm\)5% and traces are offset from each other for clarity. Reprinted from [PERSON] et al. [25]. Copyright (2020), with permission from Elsevier. Finally, [PERSON] et al. [25] reported analyses based on ultra-small-angle X-ray scattering (USAXS), small angle X-ray scattering (SAXS), and wide-angle X-ray scattering (WAXS) that were consistent with the aforementioned results. When comparing these datasets with complementary data from sorption and mercury porosimetry, no consideration was given to the fact that scattering techniques can probe disconnected porosity as well. Figure 5 graphically summarises the trends found for pore sizes, and links shale fracture/pore types and size classes with the analytical techniques applied. The authors of that study concluded that CO2 and H2O reactivity with shale can dramatically change the pore scale variability by opening and closing pore networks over the meso- to nano-pore range. The time dependence of the reactions was not included in these studies; therefore, no conclusions can be made about how continuous and sustained these porosity changes are. In other similar work, Bakken core fragments were exposed to both CO2-saturated synthetic formation brine and dry scCO2 by [PERSON] et al. [53]. Dry samples were treated at 115 \({}^{\circ}\)C and 30 MPa for 23 days. The Bakken samples were fine-grained sandstone, and several of their constituent minerals are also to be found in Sleipner caprock. The porosity  
Figure 5: Schematic linking shale fracture and pore types and size classes with the analytical techniques applied to investigate the reactivity of Utica outcrop and production samples. (**A**) Fracture and pores present within mudrock: hydraulic fractures, natural fractures, interparticle and intraparticle pores associated with the mineral matrix, and organic-matter pores associated with the organic matrix. (**B**) Analytical techniques used to examine pore size distributions and porosity characteristics in mudrocks. (**C**) Pore size classification developed by [PERSON] et al. [52]. (**D**) Pore size trends with Utica outcrop and production samples following reaction with CO2 and H2O. Green arrows represent data from scanning electron microscopy, blue arrows represent data from CO2 and N2 low-pressure gas sorption isotherm measurements, purple arrows represent data from mercury intrusion porosimetry measurements, and orange arrows represent data from X-ray scattering methods. Reprinted from [PERSON] et al. [25]. Copyright (2020), with permission from Elsevier. of the Bakken material was low since primary pores were filled with carbonate cements, pyrite, and clay-sized materials. XRD analysis showed that the minerology of unreacted Bakken consisted of 53.1% quartz, 22.2% dolomite, 7.6% illite, 7.0% calcite, 4.2% K-feldspar, 3.2% muscovite, 2.1% abite, and 0.7% pyrite.