Study of asphaltene precipitation during CO2 injection in light oil reservoirs

CO2 injection is considered as one of the successful methods used for enhanced oil recovery (EOR) in oil fields to recover residual oil. It increases mobility and reduces viscosity and interfacial tension. Asphaltene precipitation and deposition phenomena appear in petroleum reservoirs due to change in temperature, pressure, and liquid phase compositions; either during the primary production or enhanced oil recovery processes. Asphaltene precipitation might occur due to CO2 injection in light oil (>30° API) reservoirs which may cause blockage of production system, decrease in permeability, wellbore plugging and change in porosity. Experimental data concludes high asphaltenes precipitation and lower asphaltene solubility in light oils. Hence severe damage to formation can happed sue to asphaltene precipitation, in some cases the loss might be irreversible. This paper furnishes the investigation of asphaltene precipitation caused by CO2 injection. In this regards interaction between asphaltene and formation, precipitation quantity under different injection flow rates of CO2 at the constant injection pressure have been investigated. Results conclude that there is direct proportionality between asphaltene precipitation and amount of injected gas in the core sample, whereas inverse proportionality between asphaltene precipitation and increased injection flow rate of the gas at constant injection pressure.