Experimental and Modelled Reactions of CO2 and SO2 with Core from a Low Salinity Aquifer Overlying a Target CO2 Storage Complex

Abstract

CO 2 -induced reactions in low salinity aquifers overlying CO 2 storage sites are of interest to understand potential reactions or impacts in the possible case of a leak. Previous investigations of overlying aquifers in the context of CO 2 storage have focused on pure CO 2 streams, however captured industrial CO 2 streams may contain ancillary gases, including SO 2 , O 2 , NOx, H 2 S, N 2 , etc., some of which may be more reactive than CO 2 when dissolved in formation water. Eight drill cores from two wells in a low salinity sandstone aquifer that overlies a target CO 2 storage complex are characterised for porosity (helium, mercury injection, or micro CT), permeability, and mineral content. The eight Hutton Sandstone cores are variable with porosities of 5.2-19.6%, including carbonaceous mudstones, calcite cemented sandstones, and quartz rich sandstones, common lithologies that may be found generally in overlying aquifers of CO 2 storage sites. A chlorite rich sandstone was experimentally reacted with CO 2 and low concentrations of SO 2 to investigate the potential reactions and possible mineral trapping in the unlikely event of a leak. Micro CT characterisation before and after the reaction indicated no significant change in porosity, although some fines movement was observed that could affect permeability. Dissolved concentrations of Fe, Ca, Mn, Cr, Mg, Rb, Li, Zn, etc., increased during the reaction, including from dissolution of chlorite and trace amounts of ankerite. After~40 days dissolved concentrations including Fe, Zn, Al, Ba, As and Cr decreased. Chlorite was corroded, and Fe-rich precipitates mainly Fe-Cr oxides were observed to be precipitated on rock surfaces after experimental reaction. Concentrations of Rb and Li increased steadily and deserve further investigation as potential monitoring indicators for a leak. The reaction of chlorite rich sandstone with CO 2 and SO 2 was geochemically modelled over 10 years, with mainly chlorite alteration to siderite mineral trapping 1.55 kg/m 3 of CO 2 and removing dissolved Fe from solution. Kaolinite and chalcedony precipitation was also predicted, with minor pyrite precipitation trapping SO 2 , however no changes to porosity were predicted.

Review on the Mechanism of CO2 Storage and Enhanced Gas Recovery in Carbonate Sour Gas Reservoir

“…Dong [31] applied TOGUHREACT to simulate the changes of formation pressure, fluid pH, ion content, mineral dissolution, precipitation, reservoir physical properties, and CO 2 storage, and studied the influence of CO 2 -water-rock interaction on reservoir properties. Pearce [32] experiment found that in sandstone rich in chlorite, when CO 2 reacts with low concentration SO 2 , rock porosity will not increase, but there is particle movement, which damages permeability. Ahmat [33] In order to better understand CO 2 -water-rock interaction, Different mineral compositions and fluid salinity were numerically simulated and experimentally analyzed.…”

Metal Mobilization From CO2 Storage Cap-Rocks: Experimental Reactions With Pure CO2 or CO2 SO2 NO

“…The trace metal mobilization response to impure CO 2 injection is even less well known than that from pure CO 2 injection (Pearce et al, 2015a;Marcon and Kaszuba, 2015;Pearce et al, 2019d). Real potential or perceived public concerns for the risk of CO 2 and brine or formation water leakage into low-salinity aquifers has led to recent interest in the potential impacts on water quality (Lawter et al, 2016;Kharaka et al, 2018;Pearce et al, 2019c). Recent work includes the study of natural sites of CO 2 accumulation and CO 2 or brine leakage up faults, fractures, or old wellbores (Viswanathan et al, 2012); field studies of deep or shallow CO 2 injection sites (Zheng et al, 2009;Yang et al, 2013); experimental studies of mineral reactions from drill core resulting in metal mobilization (Shao et al, 2014;Golding et al, 2019;Shao et al, 2020); and transport or geochemical modeling studies to predict if leakage could be expected and if metal mobilization would be of sufficient magnitude to cause a risk or if metals are resequestered by adsorption and re-precipitation of minerals (Carroll et al, 2014;Zheng et al, 2016;Pearce et al, 2021b).…”