Modeling the Geochemical Impact of an Injection of CO2 and Associated Reactive Impurities into a Saline Reservoir

Abstract : Numerical simulations performed with the TOUGHREACT code focus on the chemical reactivity of deep reservoir rock impacted by an injection of CO2 and associated reactive impurities (mainly SO2 and O2). A simplified two-dimensional radial geo-model representing the near wellbore domain of a saline reservoir enabled us to capture the global geochemical behaviour of this underground zone. Two ratios CO2/SO2 are investigated. The results of the numerical simulations highlight the high reactivity of the near-well zone in the case where ancillary gases (SO2 and O2) are injected with CO2 with dissolution of carbonates and precipitation of sulfate minerals. Major reactions occur in the reservoir formation, whereas clays of the caprock are only slightly affected by the injection of CO2 and associated reactive impurities.