Structure of the Proterozoic Complex of the Kama-Belsky Trough (Northeastern Russian Plate): Formation Conditions, Filtration and Capacity Properties of Rocks, Parameters for Modeling Migration-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 3500 m) geofiltration structure of the Proterozoic section. Based on an 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. Moreover, well-defined potentially lateral conductive strata have been identified in the Riphean (Rotkovsky, Tukaevsky, and Leonidovsky formations) and Vendian (Baikibashevsky (Kykvinsky) formation) deposits. Based on the results of laboratory studies of 1600 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 dependences, (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 trough. 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 Arlansky-7000 well is presented.