The effects of N2, CH4 and CO2 injection on asphaltene precipitation have been experimentally investigated using a reservoir oil fluid from south of Iran, making use of light transmission method. The results are compared and the effects of injected gases on reducing asphaltene colloidal stability in oil are found in the following order: CH4> N2>CO2. It is observed that CO2 can act like an inhibitor and can increase the solubility of asphaltene, decreasing the asphaltene precipitation onset. A thermodynamic discussion explains the effect of CO2 on the solubility of asphaltene based on the solubility parameters of recombined oil and CO2, calculated from Peng-Robinson equation of state along with an empirical correlation for volumetric properties of CO2.
Jamaluddin AKM, Joshi N, Lwere F, Gurpinar O, SPE International Petroleum Conference and Exhibition in Mexico, Villahermosa, February 2002 (SPE Paper 74393).
Creek JL, Buckley JS, Wang J, SPE 2008 Offshore Technology Conference, Houston, Texas, U.S.A., May 2008 (SPE Paper 19690).
Hu YF, Liu SLN, Chu YP, Park SJ, Mansoori GA, Guo TM, J. Pet. Sci. Eng., 41, 199, 2004
Hajizadeh A, Ravari RR, Amani M, 2009 SPE/EAGE Reservoir Characterization and Simulation Conference, Abu Dhabi, UAE, October (2009) (SPE Paper 123368).