Experimental Study of the Biochemistry Method for Enhancing Oil Recovery in the Oil Reservoir after Polymer Flooding

Abstract

A delayed cross linked gel profile control agent is used to plug high permeable formations. Also, well nutrient fluid and microbes are injected with 50% of the heavy residual oil, after polymer flooding, in order to improve oil recovery due to the complex environment of oil reservoirs. Four strains of polycyclic aromatic hydrocarbon-degrading bacteria are selected from oilfield produced water with a high efficiency. Two of the four strains, namely BISYX17 and BISYX14, are new. Polycyclic aromatic hydrocarbon-degrading bacteria have high growth activity and they are able to reach a maximum stain concentration after being cultured 4 to 8 days, using phenanthrene as their sole carbon source. They are able to effectively degrade heavy hydrocarbon with a phenanthrene degradation rate of up to 80％, after the sample is cultured for seven days. Strain BISYX7 has the strongest phenanthrene -degrading ability, with a maximum degradation percentage of 89.89％. The strains are capable of producing dioxygenase to open rings of polycyclic aromatic hydrocarbon. The dioxygenase activity, produced by BISYX17, is able to reach 40.2 IU/mg, which is higher than the enzyme activities of a wild strain. This shows the strain has excellent potential to produce enzymes. Enzymes, produced by metabolism, have a direct degradation rate of 68% on crude oil. A core displacement simulation experiment indicates a profile control oil-displacing system is able to improve crude oil recovery efficiency by 17%, after polymer flooding. Thus, the system has excellent application potential for residual oil recovery.