Moein Jahanbani - MSc Students of Petroleum Reservoir Engineering, Sharif University of Technology
Shahab Alfkhani - MSc Students of Petroleum Reservoir Engineering, University of Tehran
Jamshid Moghadasi - PhD of Petroleum Engineering, Petroleum University of Technology

Selection of best microorganisms for MEOR is an important point that must be considered. In this survey the comparison between 4 indigenous species of one of the Iranian oil field was done. The potential of each species in producing biosurfactant was evaluated by IFT measurements. Since the temperature of the reservoir is almost constant during water injection, just effect of salinity was studied by incubating microorganisms in 2 levels of low salinity and high salinity medium. 10 IFT experiments were performed in the 40ᵒC and in two expensive and cheap media was used as nutrient. Medium with composition of Reservoir brine and essential elements for bacterial growth was used for simulating reservoir condition. Results show that for all of the bacteria which were used in this investigation at high salinity the microbial recovery efficiency decreased. The best species detected in each level; the best species is bacteria that decrease IFT more in its level. For 1 day incubation in low salinity medium maximum decrease of 22.7 mN/m observed. In the high salinity medium after 6 day incubation, 6.5mN/m decrease observed.

MEOR, IFT, Salinity, indigenous species