Reactive transport modeling of CO2 and SO2 injection into deep saline formations and their effect on the hydraulic properties of host rocks

Subsurface geochemical fate and effects of impurities contained in a CO2 stream injected into a deep saline aquifer: What is known

“…These values are comparable to those obtained in the simulations of Palandri and Kharaka (2005), and again low pH results from the formation of sulphuric acid. The direct oxidation of SO 2 by co-injected O 2 is the proposed mechanism to generate sulphuric acid mentioned in Knauss et al (2005), Andre et al (2012Andre et al ( , 2014,) and Bacon et al (2009); specific reactions are described in other works (e.g., Xu et al, 2007;Xiao et al, 2009). The low pH values led to significant mineral dissolution and porosity enhancement in the near-wellbore region, with the material dissolved near the well bore re-precipitated further from the injection well in the form of carbonate (e.g., calcite, siderite, magnesite, ankerite, and/or dawsonite) and sulphate (anhydrite and/or alunite) minerals.…”

“…Several reactive transport modelling studies (Knauss et al, 2005;Xu et al, 2007;Xiao et al, 2009;Andre et al, 2012Andre et al, , 2014Bacon et al, 2009) have modeled the co-injection of SO 2 with CO 2 into both limestone and siliciclastic formations. Generally, these studies predicted the formation of a highly acidified zone around the well bore, with local pH values in the range 0-1.…”

“…The paper by Bacon et al (2009) is very brief, but worthy of comment as the numerical treatment included injection of a single CO 2 -SO 2 gas phase. No detail was presented as to the chemical processes transforming the SO 2 components to SO 4 −2 , but the simulation results showed extensive anhydrite precipitation near (∼5 m) of the well bore, with no mention of other sulphate minerals forming further afield.…”

Molecular interactions of SO2 with carbonate minerals under co-sequestration conditions: A combined experimental and theoretical study

“…Carbonate formations are also of considerable importance in geologic storage of CO 2 in their capacity as caprock and injection reservoirs (Bacon et al, 2009;Wollenweber et al, 2010;Bachaud et al, 2011). With the growing interest in CO 2 sequestration and reactivity in the ensuing supercritical CO 2 environments (Lin et al, 2008;Bakri and Zaoui, 2011), there is a need to understand how these transformation reactions occur with carbonate rocks exposed to scCO 2 -dominated fluids.…”

Numerical investigation of the partitioning phenomenon of carbon dioxide and multiple impurities in deep saline aquifers

“…Many investigations have put emphasis on the geochemical effects of the impurities contained in the CO 2 streams, including the brine acidification effects by co-injected SO 2 , NO 2 , or H 2 S and the corresponding effects on the porosity and permeability of reservoir and caprock, e.g. [10][11][12][13][14][15], and the hydrocarbon oxidation by the O 2 impurity, e.g. [16][17].…”