The group of BS reservoirs in the Gubkin oil and gas region is characterized by the fact that the water cut in the well production is ahead of the oil production by more than 12%. The increase in the dynamics of watering of BS10 strata in the zones of lack of underlying water is associated with its breakthrough from the injection wells. The reason for this is the insufficiently effective system of stimulation of the reservoir - the inability of injected water to displace oil from the reservoir. This problem is directly related to the geological factor, the variability of reservoir properties. The study of the material composition of reservoir rocks in order to assess the reservoir properties and their influence on the displacement coefficient has been carried out. Research objectives include statistical analysis of changes in clay content from porosity and permeability of rocks of the BS10 reservoir formation; establishing the effect of clay on the permeability of the reservoir. For the BS10 reservoir group of the Gubkin oil and gas region, it was found that in highly porous hydrophobic reservoirs with a low clay content, displacement is less intense compared to hydrophilic low permeability reservoirs.