Effect of a GBK acidic system developed by the Institute of Petroleum Chemistry of the Siberian Branch of Russian Academy of Sciences (IPC SB RAS), on the composition of oil produced and on the reservoir microflora has been studied under both laboratory and field conditions. Under laboratory conditions, the integrated effect of the reservoir microflora and the acidic system manifested itself in a growth in the degrees of oxidation and aromaticity of the oil, in changes in its group composition and molecular weight distribution of mono-, bi-, and triaromatic hydrocarbons, as well as in the content of cyclones. Under field conditions, the efficiency of the GBK acidic treatment of low-productivity wells amounted to about 2,000 tons of incrementally produced oil per well job. This was achieved due to the inclusion of additional interlayers having different oil compositions and due to the desorption of polar compounds in the course of acid dissolution of the carbonate matrix.