Visual Investigation of Pore-Scale Salt Precipitation during CO2 Injection in Carbon Capture and Storage and Enhanced Oil Recovery Processes

Summary Formation damage is a general term that describes factors harming well productivity and injectability. To mitigate the greenhouse effect caused by the presence of carbon dioxide (CO2) in the atmosphere, scientists have proposed storing CO2 in depleted oil and gas reservoirs, aiming to result in enhanced oil recovery (EOR). This approach, despite its benefits, can also result in formation damage, including salt precipitation, leading to reduced porosity and permeability, thereby affecting injectability and productivity. In this study, we used glass micromodels with homogeneous and heterogeneous patterns to comprehensively and visually investigate the salt precipitation during CO2 injection in carbon capture and storage (CCS) and EOR processes. In addition, we ivestigated virtually the impact of porous media type, brine concentration, CO2 injection flow rate, and different salt types, as well as a comparative analysis of these variables. Three different brines containing sodium chloride, calcium chloride, and potassium chloride were utilized, using reservoir oil experiments. With increasing salt concentration, salt precipitation increased in all parts of the porous media, and with increasing CO2 injection rate, the amount of salt precipitation decreased, especially at the entrance of the porous media. In the homogeneous micromodel, more salt precipitate formed than in the heterogeneous micromodel, and the distribution of salt precipitation was more regular because it had more regular pores and porosity. The amount of salt precipitation in CCS is more than in EOR because, in CCS, the amount of brines in pores is more. Sodium chloride salt caused more precipitation during CO2 injection due to its lower van der Waals radius than other salts.