mansoureh farid

The most important mechanism of microbially enhanced oil recovery processes is changes in interfacial properties of fluid/fluid/rock affected by bacterial cells and their metabolites. In this study, two bacteria B.licheniformis and P.putida and three different sources of carbon were used. Results showed that due to the effect of carbon source on bacterial growth and also type and value of produced metabolites, changes in interfacial properties of fluid/fluid/rock is affected by used carbon source. The better growth of both bacteria occurred in a culture medium containing glucose. Pendant drop tensiometry, electrophoretic mobility measurement, interfacial dilational rheology and contact angle test were used to investigate the effect of cell structure and culture medium composition on interfacial tension reduction, emulsion stability, and wettability alteration mechanisms. The results of this section showed more potential of P.putida bacteria in surfactant production. Also, results showed that glucose is a better culture medium for B.licheniformis bacteria. Produced biosurfactants and bacterial culture of B.licheniformis bacteria in medium with glucose carbon source reduced surface tension and interfacial tension by 29.07% and 43.87%, respectively. Submerging thin section in glucose culture medium of B.licheniformis bacteria reduced the contact angle of water drop from 109.081 to 44.898°. In the case of P.putida bacteria, the oily and glucose culture media are respectively the effective media for influencing the fluid-fluid and fluid-rock interface. The produced biosurfactants and bacterial culture of P.putida bacteria in medium with olive oil carbon source reduced surface tension and interfacial tension by 36.4% and 27.1%, respectively. The contact angle of drop water was reduced from 109.081 to 54.050° in glucose culture medium of P.putida bacteria