Genesis of authigene carbonate minerals in the Upper Cretaceous reservoir, Honggang Anticline, Songliao Basin: A natural analog for mineral trapping of natural CO2 storage

Dawsonite (NaAlCO3(OH)2), as a trace mineral of CO2, is abundant in the upper Cretaceous Reservoir of the Honggang Anticline, southern Songliao Basin. Petrologic and isotopic geochemical characteristics have been investigated by a polarizing microscope, a scanning electron microscope (SEM), X-ray diffraction (XRD), cathode luminescence (CL), fluid inclusions and carbon–oxygen isotopic analysis. The diagenetic sequence indicated that dawsonite, late-generation microcrystalline quartz, late-generation kaolinite, late-generation calcite and ankerite was formed after CO2 flooding. Meanwhile, as a function of analysis on carbon–oxygen isotope, the mantle-magmatic CO2 provided a carbon source for the precipitation of dawsonite, late-generation calcite and ankerite. The three kinds of carbonate minerals mentioned earlier grew in a progressively evolved condition. Using a basic thermodynamic fraction equation, the total quantity of natural CO2 captured by dawsonite-bearing sandstones per cubic meter was calculated to be 99.51 kg.