Migration of fines plugs the flow channels and creates new channels. Profile modification on pore scale. Also clay swelling which squeezes out oil from pores.
Lowering Ca concentration of injected brine leads to calcium carbonate dissolution. As a result, the polar components of oil would be released from rock surface.
With increasing pH, zeta potential is towards positive and with increasing salinity has less influence. Mineral dissolution exists with 25 times diluted SW.
13
Electric double layer effect
Ligthelm et al. [1]; Nasralla and Nasr-EL-Din [20, 21]
Zeta potential studies
By decreasing the pH of LSW, the electric charges of oil/brine and rock/brine surfaces changed from highly negative to close to zero value, which means that the expansion of EDL was reduced.