Oil recovery from polar components (asphaltene and SA) treated chalk rocks by low salinity water and water containing SO42− and Mg2+ at different temperatures

Potential enhanced oil recovery by imbibing distilled water (DW expressed as low salinity water) into modified chalk is discussed in this paper. Average recovery of about 80% is estimated at different temperatures, 50, 70 and 90 °C for cores treated with asphaltene and stearic acid (SA).A synergistic effect between asphaltene and SA for alteration of chalk to more oil wet is also demonstrated.Aging time of 2 weeks for the used system is shown to be sufficient for imbibition experiments, where about 2.4% difference in oil recovery between the aged cores for 2 weeks and 6 months is observed.Presence of SO42− in DW is shown to be more effective than that for DW in imbibition experiments at temperatures up to 50 °C. The recovery rate with low salinity water is shown to be higher, reaching the maximum recovery potential earlier than that with SO42− as imbibing fluid. It is interesting to see that a large reduction in the potential oil recovery is observed when DW contains Mg2+ is used as an imbibing fluid for cores treated with asphaltene. This is perhaps due to a molecular interlock phenomenon that enhances oil trapping.