Hydrothermal Modelling of Formation of Secondary Reservoirs in Siliceous Limestones (H2O-CO2 System)

Summary The results of hydrothermal modeling of the formation of secondary reservoirs (hydrothermal silicites) in siliceous limestones in the H2O-CO2 system are considered. Equilibrium mineral associations were established for various values of temperature and CO2 content in the composition of the hydrothermal fluid. The causes of silicification of the surface of siliceous limestone specimens have been identified. The most stable and, on the contrary, the most unstable minerals in hydrothermal conditions that are part of siliceous limestones have been established. The sizes of secondary voids of hydrothermal origin are determined. On the basis of the obtained data, it was concluded that the resulting hydrothermal silicites, due to the predominance of small voids in them, will contain large amounts of residual water.