Multi-scale block structure of natural reservoirs and its effect

It has been established that in conventional and unconventional natural hydrocarbon reservoirs, there are subvertical channels that are extended laterally and thin, low-permeable barriers between small-scale blocks. These barriers determine reservoir filtration resistance and break the hydrodynamic connectivity between small-scale blocks in accordance with Darcy's law. Generally, the gas and liquids flow through these barriers and along these channels occurs only at pressure gradients above some initial value. When the formation pressure decreases during reservoir development, low-permeable rock deformations occur in the crushing zones, which arise during neotectonic movements. The deformation of these low-permeable rocks causes a decrease in the filtration properties of existing low-permeable barriers and the appearance of additional barriers in the crushing zones. This causes an increase in the reservoir filtration resistance and the formation of stagnant zones, in which non-recoverable hydrocarbon reserves remain in the development system used. These barriers cannot be detected by seismic survey methods.