Structure of the Proterozoic Complex of the Kama-Belsky Trough (North-East of the Russian Platform): Conditions of Formation, Filtration and Capacity Properties of Rocks, Parameters for Modeling of Migration and Accumulation Processes

The article discusses the structural and tectonic features of the Riphean-Vendian section of the Kama-Belsky Trough. It is shown that its formation is determined by the layered-block (up to a depth of 3500 m) and block (at a depth of more than 3,500 m) geofiltration structure of the Proterozoic section. Based on the analysis of the lithological composition of the deposits of the Kama-Belsky Trough, the following were identified: (i) regionally developed lateral conductive strata, (ii) low-permeability strata with subordinate development of reservoirs, and (iii) subvertical permeable zones. In addition, well-defined potentially lateral conductive strata are identified in the Riphean (Rotkovskaya, Tukaevskaya, and Leonidovskaya formations) and Vendian (Baikibashevskaya (Kykvinskaya) formation) deposits. Based on the results of laboratory studies of 1,600 core samples, a range-based assessment of the filtration and capacity properties of the most typical lithotypes of Proterozoic rocks was performed. A comprehensive assessment of the filtration and capacity properties of rocks was conducted, including (i) empirical dependencies, (ii) the fractional lithological composition of objects, and (iii) the analysis of lithotypes taking into account the layered-ordered and layered-disordered structures. To carry out modeling of migration-accumulation processes in the factor-range formulation, expert parameters of permeability for various lithotypes of rocks are introduced. The assessment of the weighted average permeability and the comparison of the calculation results are carried out on the basis of the sections of individual wells with the subsequent generalization for the territorial zones of the Kama-Belsky depression. As an example, the calculation of the permeability range of geofiltration elements for a model of layered-ordered and layered-disordered lithological structure of the formation based on the data from the Arlanskaya-7000 well is presented.