Analysis of asphaltene deposition, carbonate precipitation, and their cementation in depleted reservoirs during CO2 injection

Carbon dioxide (CO2) injection in depleted oil reservoirs is a potential means of reducing CO2 emissions. In this regard, CO2-related formation damages are considered key technical and economical issues. When CO2 is injected after water flooding, it can be stored by hydrodynamic trapping, dissolution, and mineral trapping. This process leads to the formation of carbonic acid, which may react and dissolve the carbonates. The precipitation of these carbonates can reduce oil productivity and CO2 injectivity. In this study, we develop an analytical model to predict the amount of asphaltene deposition, rock dissolution, and their cementation. Primarily, we develop an analytical model that treats the asphaltene deposition and carbonate dissolution in radial geometry. Then, this model predicts cementation, which is evaluated to determine the effect of cementation on reservoir permeability. Finally the developed model is compared with experimental data and determined the factors affecting the cementation. From analyses of different cases, cementation is a few percent but its percentage increases with time. The results presented in this study indicate that the amount of cementation depends on asphaltene percentage, flow rate, flow period, and reservoir depth. The model assumes constant reservoir temperature and no capillary and gravity forces. However, these forces might increase asphaltene-carbonate cementation in the reservoir.(c) 2015 Society of Chemical Industry and John Wiley & Sons, Ltd