**7. Conclusion**

In this chapter, a review of the current literature indicates that dissolution, precipitation, and fines mobilization are the main mechanisms that cause CO2 injectivity impairments especially in deep saline reservoirs. Dissolution of carbonate minerals due to CO2-brine-rock reaction is dominant and could increase the porosity and permeability of sandstone core samples. On the other hand, detachment, precipitation of salt and clay minerals and deposition of fines particles would decrease the permeability and even clog the flow paths despite net dissolution. The effect of these two seemingly opposing processes on CO2 injectivity has been clearly demonstrated

through numerous experimental studies supported by some field reports. However, the results are case dependent and lack generality in terms of quantifying the petrophysical damage.

There are many underlying parameters with positive and negative impacts on CO2 injectivity. It has been highlighted that injection scheme (flow rate, time frame), mineral composition (clay content, sensitive minerals), particulate process in porous media (pore geometry, particle, and carrier fluid properties), and thermodynamic conditions (pressure, temperature, salinity, CO2, and brine composition) have substantial effect on fines migration during CO2 injection. However, there is abundant room for further progress in determining the impact of different fluid-rock mechanisms on CO2 injectivity.
