Reactivity of micas and cap-rock in wet supercritical CO2 with SO2 and O2 at CO2 storage conditions

Abstract

Seal or cap-rock integrity is a safety issue during geological carbon dioxide capture and storage (CCS). Industrial impurities such as SO 2 , O 2 , and NOx, may be present in CO 2 streams from coal combustion sources. SO 2 and O 2 have been shown recently to influence rock reactivity when dissolved in formation water. Buoyant water-saturated supercritical CO 2 fluid may also come into contact with the base of cap-rock after CO 2 injection. Supercritical fluid-rock reactions have the potential to result in corrosion of reactive minerals in rock, with impurity gases additionally present there is the potential for enhanced reactivity. The first observation of mineral dissolution and precipitation on phyllosilicates and CO 2 storage cap-rock (siliciclastic reservoir) core during water-saturated supercritical CO 2 reactions with industrial impurities SO 2 and O 2 at simulated reservoir conditions is presented.

New experimental density data and derived thermophysical properties of carbon dioxide – Sulphur dioxide binary mixture (CO2 - SO2) in gas, liquid and supercritical phases from 273 K to 353 K and at pressures up to 42 MPa

“…Similar to injection of acid gases, i.e., injection of CO 2 -H 2 S [9] [10], technically, CO 2 and SO 2 can be co-stored in deep saline aquifers and this effectively reduces the capture cost by avoiding SO 2 removal costs [11] [12] [13]. However, the reactivity of SO 2 with rock in the presence of water and acids that form is an issue of concern [14] [15] [16]. The geochemical effects can reduce the pH of the formation water, change the porosity of reservoir rock and cause mineral dissolution and sulphate precipitation [11] [17] [18] [19] [20].…”

Mineralogical controls on porosity and water chemistry during O 2 -SO 2 -CO 2 reaction of CO 2 storage reservoir and cap-rock core

“…The majority of experimental and geochemical modelling studies of CO 2 -water-rock interactions, however, have used pure CO 2 . Relatively few studies have presented experimental and modelling data with the presence of one or more impurity gases, and data for O 2 or NOx co-injection are extremely sparse (Pearce et al, 2016). SO 2 has been observed to acidify formation water, enhancing silicate dissolution, and also to reduce Fe 3+ to Fe 2+ making it available for mineral trapping as siderite or formation of sulphate minerals (Palandri and Kharaka, 2005;Pearce et al, 2015b).…”

6. Multiphase Multicomponent Reactive Transport and Flow Modeling

“…Some of potential co-injected impurities modify and promote geochemical reactions. This indicates that gas and its geochemical reactions have a significant influence on the entire porous medium, e.g., host water/brine and rocks (Jung et al 2013;Sterpenich et al 2013;Lu et al 2014;Pearce et al 2015Pearce et al , 2016aLu et al 2016) and engineered materials such as cement-based wells (Jacquemet et al 2005). Models should be able to follow such modifications of the fluid and matrix and accurately quantify their effect on associated properties using a general or specific EOS.…”