Experimental Investigation of the Effects of Water Salinity and Initial Wettability on Oil Recovery

The low salinity water flooding caused an increased secondary and tertiary oil recovery in many laboratory and field tests. The extent of the reactions and interactions of this type of flooding led researchers to investigate and find the main mechanisms¡ governing this process. To describe the interactions¡ numerous mechanisms such as¡ fines migration¡ increase in pH¡ multiple ion exchange and electric double layer effect have been noted¡ but none of them¡ has not been accepted as a comprehensive mechanism due to the complexity of the crude-oil-brine-rock interactions. So far¡ most of what has been suggested in previous research was creating a favorable wettability state with dilute brine injection. In this laboratory experiments that take place on sandpacks¡ the effects of brine salinity¡ aging of oil in packs and the fines have been investigated on recovery of oil¡ end point water relative permeability in each salinity and wettability alteration. The obtained results from dilute brine injections show that without the presence of minerals and divalent ions and with NaCl brine¡ tertiary recovery was increased¡ and of course this increase was higher for the aged sample. Also¡ the wettability alteration towards more water wet has been probed by means of flooding data.