Method for improving recovery ratio of heavy oil reservoir through microbial composite flue gas

The invention belongs to the technical field of tertiary oil recovery, and particularly relates to a method for improving the recovery efficiency of a heavy oil reservoir through microbial composite flue gas. The method comprises the following steps: screening test oil reservoirs, wherein the screening of the test oil reservoirs needs to meet two conditions of oil reservoirs and florae; pretreating flue gas; injecting desulfurized and denitrified flue gas and a microbial oil recovery injection agent; carrying out subsequent water drive displacement; water well injection is stopped, and oil well downcomer production is conducted. The method has the advantages that the field implementation process is simple, the energy consumption is low, the national environmental protection requirements of energy conservation and emission reduction are met, and the method is a green, environment-friendly and efficient thickened oil cold production technology; the method has the advantages of being low in cost, high in input-o