Monitoring of Asphaltene Molecular Weight Distribution at Different Conditions of Pressure and CO2 Injection

This work concerns to observe the pressure as well as CO2 mole fraction effects on asphaltene molecular weight distributions (MWD) at reservoir conditions. The high-pressure high-temperature asphaltene measurement setup applied, and the amount of precipitated asphaltene at different pressures as well as CO2 mole percent in one of Iranian crude oils was measured. The GPC apparatus was used for characterization of asphaltene molecular weight under different conditions. It has been observed that some thermodynamic changes such as pressure depletion, above bubble point, as well as CO2 injection increase the average molecular weight of asphaltene, and cause the asphaltene MWD changes from a bimodal curve with two maxima to a single maxima curve. Reversely, below the bubble point, pressure reduction causes a decrease in the average molecular weight of asphaltene, and also causes the shape of asphaltene MWD partially restore which might be due to dissolution of asphaltene aggregates. The results of this work can be imported to thermodynamic models which use polydisperse data of heavy organic fractions to enhance their performance at reservoir cond

Keywords:

Asphaltene , Asphaltene molecular weight distribution , Pressure depletion , CO2 injection , Experimental measurement