Application of Biosurfactants to Wettability Alteration and IFT Reduction in Enhanced Oil Recovery From OilWet Carbonates

To obtain potentially applicable microorganisms to an effective in situ microbial enhanced oil recovery operation, bacteria that were compatible with the harsh conditions of a petroleum reservoir were isolated from a crude oil sample. The application of an oil spreading technique showed that all of the isolates were capable of producing biosurfactants from both the glucose and crude oil as carbon sources. The secreted biosurfactants could at least reduce the surface tension 20 mN/m and for one of the isolates; the surface tension value dropped below 40 mN/m. In addition, the contact angle measurements revealed that the produced biosurfactants could effectively alter the wettability of the oil saturated rock samples. At last, the effect of isolates and their biosurfactants on improving oil production from oil saturated rock samples was investigated. It was observed that the presence of bacteria in the system could increase the amount of produced oil in comparison with the case where cell free biosurfactants were utilized.