Experimental Investigation of Rock and Fluid Interaction during CO2 Injection in a High Permeable Heavy Oil Sandstone Reservoir

Rock and fluid interactions play an important role in many aspects of formation evaluation and reservoir characterization studies. Chemical reaction of the injected fluids with reservoir rock and fluid affects the efficiency of EOR processes due to alteration of oil and rock petrophysical properties. Hence, it is necessary to investigate these interactions during EOR operations. In this study, the effect of gas injection velocity and pressure, and injection orientation on rock and fluid interaction are investigated during CO2 injection, as tertiary recovery mechanism, into a high-permeable heavy oil sandstone reservoir. The oil and sand samples have been taken from an Iranian southern oil reservoir. The results of the orientation effect of the sandpack model show that due to the gravitational stability of the vertical injection, the dissolution of the minerals as well as the asphaltene precipitation is more than the horizontal injection mode. Also, the results indicate that as the injection pressure increases, the dissolution of minerals and asphaltene precipitation also increases. This is due to the fact that by increasing pressure, more CO2 is dissolved in crude oil and water. In addition, as the injection velocity decreases, the contact time between the formed acid and the rock as well as CO2 and crude oil increases. Therefore, the possibility of dissolution of minerals and asphaltene precipitation increases.