Experimental investigation of the influence of carbonated water on sandstone and carbonate rock properties

Laboratory measurements using nuclear magnetic resonance, scanning electron microscopy, and gas porosity and permeability analysis were conducted to acquire a petrophysical interpretation of the Carbon Tan Sandstone and Savonnieres Carbonate for potential carbon dioxide storage in subsurface formations. The relationships between pore structures, such as pore-size distribution, pore geometry, and porosity/permeability, were investigated near and far from the wellbore. At operating pressures of 2500psi (17.24 MPa) and temperatures of 176 °F (50 °C), carbonated water was injected into a composite core constructed of two similar core samples bounded by a compact disc located between them. The current results showed that a strong calcite dissolution took place near the injection position of both rock samples and led to improvements in the primary intergranular permeability and porosity, while the carbonate sample showed significant improvement compared to sandstone. The durable heterogeneous dissolution of calcite grains also led to the creation of new pores as intra-granular micro-pores. While at deeper depths from the injection position, it noticed an insignificant development in pore structure and its populations as well as rock hydraulic properties of both rock samples. In conclusion, the study revealed that the injected carbonated brine had a valuable impact on fluid-formation interactive, which improved rock's inlet properties compared with outlet.