Performance evaluation of produced biopolymers by native strains on enhanced oil recovery

Bio(polymer) flooding is one of the most promising strategy used to recover additional oil from mature reservoirs. Bio(polymers) decrease the mobility ratio, improving the sweep efficiency of injected fluid and consequently, increasing oil recovery. Therefore, in this research seven unknown strains were isolated from the soil of the Masjed‐Soleiman oil field, and then studied for biopolymer production. After biopolymer production and viscosity tests, two of the best strains were selected. Their performances were evaluated in the enhanced oil recovery in micromodel media. The main purpose of this research is to identify the biopolymer‐producing species, but the effective parameters in the production of more biopolymers and enhanced oil recovery are also evaluated and optimized. The experiments optimized by the Design Expert software by the general factorial method. The parameters evaluated include different types of strains, biopolymer concentration (three levels of 500, 5500, and 10,500 ppm) and the salinity of the injected fluid (three levels of 0%, 0.5%, and 10%). The best performance in oil recovery for both strains of TMU57 and TMU59 are considered in the biopolymer concentration of 10,500 ppm and the concentration of NaCl equal to 10 wt%. The values of the ultimate oil recovery in these conditions with the strains of TMU57 and TMU59 were 47% and 63%, respectively.