Laboratory studies show the existence of some strains of bacteria in field crude oils and formation waters. This work is concerned with studying the effect of the reservoir conditions such as temperature, salinity and lithology on the indigenous bacterial activities. Such study is an original contribution to the knowledge of microbial enhanced oil recovery (MEOR).

Egyptian MEOR project at Cairo University succeeded to isolate a surfactant-producing microorganism "Pseudomonas Aeruginosa" from crude oil produced from an Egyptian oil field. Several displacement tests were conducted in sand pack model. A modified media was used to incubate and improve the growth rate, behavior and stimulation of Pseudomonas Aeruginosa.

The results obtained from the current work showed that Pseudomonas Aeruginosa succeeded to increase the oil recovery by 20%. Pseudomonas Aeruginosa becomes able to resist the effect of temperature up to 70°C and salinity up to 150,000 ppm, when a specific incubation technique is applied. There is no significant effect on the behavior of the bacteria in the presence of the Dolomite and Kailinite inside the reservoir. The value of the oil recovery factor in case of incubation of the bacteria outside the model is greater than its value in case of incubation inside the model by about 5%.

The results obtained are discussed and analyzed in terms of surface tension, hydrogen ion concentrations, viscosity, and conductivity of the effluent solutions.

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