## 4 Results
### Mass Balance Calculation and Numerical Modelling
Both indicate calcite and dolomite dissolution coupled with secondary gypsum and illite precipitation. The described study is limited to two specific situations within the extremely complex system of CO\({}_{2}\) storage in geological structures. The time and space scales, the variability of conditions and the number of components of a laboratory experiment are very far from the real-life conditions. The discussed reactions may trigger a whole set of additional processes including the precipitation of  
Figure 6: Simplified model developed from the observed mineralogical/textured changes after the SC CO\({}_{2}\) injection in the vuggy carbonates. (**a**) Initial mineralogy and texture of the rock samples: calcite and dolomite composition and brine filling connected pore space; (**b**) Pressurized SC CO\({}_{2}\) injection begins, which dissolves in the brine (CO\({}_{2}\)-rich brine); (**c**) During supercritical experimental stage, the pressurized CO\({}_{2}\)-rich brine reacts with the rock forming minerals producing carbonate dissolution; (**d**) Pressure is released at the end of the experiment and a modified pore network remains. new mineral phases due to the increased ion concentration of the brine [25; 57], the adjustments in brine mobility due to changes in the capillary network [21] or the alteration of mechanical properties of the rock provoked by the changes in the pore network [58; 59], to name just a few. Nevertheless, our results provide some insight into the physico-chemical processes that may play a role in a CO\({}_{2}\) reservoir. It is important to take into account that the results obtained in this research must be interpreted within the context and scale of the described work (i.e., laboratory test). The study of a significantly larger number of samples together with the modelling data following the presented approach would make it possible to gain a clearer view of the precipitation and dissolution processes at a larger (i.e., reservoir) scale. This would also provide important information about the potential of the study area for geological CO\({}_{2}\) storage. Flow-through experiments might also be an alternative option to characterize the chemical reaction during CO\({}_{2}\) injection taking into account the transport effect. Finally, numerical modelling at reservoir scale integrating these experimental results could predict the potential CO\({}_{2}\) sequestration in this reservoir. The real importance of the encountered mineralogical and porosity changes is in their influence on the functionality and integrity of a storage site. Slight textural changes in the reservoir or seal rock might lead to significant modifications in the storage capacity, injection rate, geomechanical resistance, confining capacity, etc. of the whole system. To study these overall processes on more realistic time and space scales, numerical modelling has been successfully applied [4; 7; 12; 13; 14; 15] adjusting the models with experimental data such as those provided by this work. Migration of fine particles induced by either chemical or physical forces has also been described in various fields of geological reservoir use. In general, the processes and the overall effect of particle migration on the hydrodynamic properties of the rock vary depending on characteristics of the rock and the circumstances. Some authors [60; 61; 62; 63; 64] have studied the importance of fine particle migration in CO\({}_{2}\) storage and during brine disposal demonstrating its significance on flow pathways and engineered water injection. For more detailed studies, migration of fine particles should be considered.