Precipitation Kinetics of Sulfate-Bearing Minerals under Environmental Conditions during CO2 Geological Storage

Carbon Capture and Storage (CCS) has been widely recognized as one of the main technologies to mitigate climate change. Deep-saline aquifers are among the preferred potential repositories for CO₂ currently being emitted to the atmosphere from burning of fossil fuels. Large-scale injection of supercritical CO₂ into subsurface reservoirs induces a complex interplay of multiphase flow, capillary trapping, dissolution and chemical reactions that may have significant impacts on both, short-term injection performance and long-term fate of CO₂ storage. To ensure the viability of geological CO₂ storage, a holistic understanding of reactions at supercritical CO₂-water-rock interfaces and the environmental factors affecting these interactions is required. The major objectives of this contribution are to study the kinetics of CO2 brine-rock interactions and derive respective chemical reaction rate expressions under the typical conditions of CO2 storage sites. These rate laws may be used in modeling the storage sites and operating them in a way that will minimize scaling and thus potential reduction of injectivity. A new experimental system was set up at the Water-Rock interaction laboratory, Ben-Gurion University of the Negev that allows studying the interaction between CO₂, brine, and minerals under CO₂ supercritical conditions. All equipment is fully capable to deal with adjustable PTX conditions enabling continuous and computerized data acquisition of various variables including pressure, temperature, stirring speed, in-situ measurement of pH and redox potential. The experimental setup allows the measurement of dissolution and precipitation rates of diverse minerals under a wide range of environmental conditions as found in CO₂ storage sites offering the possibility to collect liquid and solid samples for further chemical and morphological analyses.