Study results of the material composition and conditions of forming P Vogulkinskaya strata of the Tolumskoye field are presented. It is established that the formation of sediments occurred in coastal-marine conditions, in the transgressive stage of the sedimentation basin development. According to the composition of the allotigenic part, the studied sandstones and siltstones correspond to the quartz, grauwack and arkose groups. The study of secondary transformations showed that the rocks of the Vogulkinskaya strata were changed to the level of average catagenesis, characterized by intensive regeneration of quartz, intra-layer dissolution of unstable micas and feldspars, hydrosludization, kaolinization and calcitization. It is established that the deterioration of filtration-capacitance properties is associated with the development of secondary carbonatization.