The article presents the laboratory studies results of enzyme-based complexes. It has been shown that to prevent a decrease in enzyme activity in reservoir conditions due to high salinity and temperature, it is necessary to include chelate compounds to limit the effect of metal ions. The results of the EDTA-chelate experiment showed that at EDTA concentrations between 2 and 0.8%, the turbidity of the enzyme solution decreased during the testing time, demonstrating the positive effect of using EDTA with enzymes in a salt water environment. On the basis of experiment the optimal enzyme solutions and surfactants concentration for the minimum surface tension value has been clarified. The optimal effect of the minimum surface tension value is 1.735 mN/m with components was obtained at the enzyme:surfactant ratio equal to 0.477:0.3. The thermal stability of the enzyme complex study results showed that the interfacial tension between the enzyme complex solution and kerosene is much less than the interfacial tension between sea water and kerosene (21.75 mN/m), and this is proof of the enzyme complex thermal stability at the reservoir temperature. Keywords: enzyme solution; thermal stability; wettability; oil recovery stimulation; surfactant.

The article presents the laboratory tests results of enzyme solutions application on the model of the White Tiger Miocene deposits. It has been established that the enzyme solutions application makes it possible to increase the oil displacement efficiency in the range of 7.23–10.59%. The values variation is associated with different core samples characteristics in terms of porosity, permeability, initial oil saturation, and in terms of lithological composition as well. After enzyme solution treatment the differential pressure decreases, which indicates a change in the oil with oil-bearing rock wettability. Keywords: Enzyme solution; reservoir model; oil displacement efficiency; wettability; bottomhole formation zone.