the results showed that wettability critically changes
during shut-in period for both in situ and ex situ processes in which
the bacteria have more chance to adhere and form bio-films or by
biosurfactant adsorption on the rock surfaces. Besides, the higher
wettability alteration obtained in ex situ test shows that biosurfactant adsorption has more potential to alter the rock wettability than
biofilm formation. Besides, the results showed that the optimum
wettability alteration based on the Anderson graphical scheme was
obtained during the ex situ microbial flooding experiments leads
to the minimum residual oil saturation. Hence, the biosurfactant
produced from E. cloacae is proposed as a good candidate for the
tertiary oil recovery process because of its high capability to reduce
IFT and changing rock wettability