Properties of novel microbial polysaccharides suitable for the polymer flooding of harsh oil reservoirs

The partially hydrolyzed polyacrylamide (HPAM) which is extensively applied to polymer flooding is poorer in the resistance to high temperature and high salinity. To solve this problem, this paper explored the feasibility of taking the novel microbial polysaccharides (diutan gum, welan gum and xanthan gum) as the polymer for oil displacement. Then, the effects of the concentration, temperature, shear rate, storing time, alkali concentration and salinity of microbial polysaccharide on its viscosity were investigated. Finally, the oil displacement effect of microbial polysaccharides was evaluated and compared with that of HPAM. It is experimentally proved that these novel microbial polysaccharides are of good water solubility, and their solution viscosity increases with the concentration. The solution presents good shear resistance and storing stability. Compared with traditional HPAM solution, microbial polysaccharide solution is much better in temperature tolerance, alkali resistance and salt endurance. Microbial polysaccharides are obviously superior to HPAM in term of oil displacement effect. Therefore, microbial polysaccharides can be used as a novel oil displacement agent suitable for harsh oil reservoirs.