Asphaltene aggregation onset during high-salinity waterflooding of reservoirs (a molecular dynamic study)

The primary objective of this study is to establish an understanding of the role of high-salinity brine on the intensity of asphaltene aggregation onset during waterflooding of petroleum reservoirs. We already have shown that asphaltenes have a high tendency to form aggregates during waterflooding process when pure- and low salinity-water are injected into reservoirs. To fulfill the present objective, molecular dynamic simulations are performed on asphaltenic-oil/aqueous systems at 550 K-200 bar. The oil phase consists of asphaltenes (10 wt.%) and ortho-xylene, in which asphaltene molecules are completely soluble. Our simulations results reveal that the salt-in effect of high-salinity brine (25 wt.% NaCl) on seven different model asphaltenic oils causes a significant reduction of the onset of asphaltene aggregation as compared with pure-water. Such salt-in effect is primarily due to a considerable reduction of water miscibility in the oil phase at high pressure and temperature.