A nanoscale insight into the formation damage of carbonate reservoir due to water incompatibility during smart water injection: a molecular dynamics study

Scale deposition on the rock surface critically influences the performance of the water flooding process in an oil reservoir. Besides altering the pore structure of porous media, the scaling process can significantly modify the distribution of ionic species at the solid-liquid interface, which subsequently changes the rock-brine interaction. Molecular dynamics simulation is utilized in this study to obtain a fundamental insight into the interfacial phenomena responsible for the precipitation and deposition of mineral scales on the calcite surface to resemble the formation damage during smart water flooding of the carbonate oil reservoir. The effect of salinity and ionic composition of injected brine is also investigated. The results indicate that the scale formation strongly controls the contribution of individual divalent ions at the interfacial zone. It has been found that smaller clusters are more prone to be adsorbed in the proximity of the calcite surface, while the larger one is located at a further distance from the rock surface. The association of monovalent ions in the interface is crucial in approaching clusters. This study also points out the profound impact of Mg2+ as an impediment to scale deposition and the effect of monovalent ion concentration on scale formation.