Geophysical processes and biosphere: article

Аnnotation: The article contains the results of studies of Botuobin, Talakh and Khamakin reservoirs of Vendian-age in the Chayanda hydrocarbon field (Eastern Siberia). The estimates of changes in the volume and compressibility of the pore space based on the analysis of changes in the petrophysical parameters of reservoirs when the effective pressure increases from 37.0 to 57.0 MPa, i.e. under conditions simulating field development for depletion, are obtained. Porosity coefficient has decreased by 0.043 absolute percent, compressibility of pore space has decreased by 0.228 1/GPa, average value of bulk compression deformation has increased by 0.096 %, which means decrease of volume of developed reservoirs by almost 0.1 % versus the beginning of development. The deformable reservoir model developed by Yu.O. Kuzmin, taking into account the geodynamic history of reservoir development, was applied to estimate the value of possible subsidence of the earth ground surface of this field. Estimates of the maximum values of possible surface subsidence during modeling of the field development process are 0.33 m with 5 MPa decrease in reservoir fluid pressure and 0.335 m with-out taking it into account dynamics of petrophysical parameters. If reservoir pressure decreases by 10 MPa, maximum drawdown is estimated to be 0.60 and 0.65 m, and if reservoir energy is completely depleted, maximum drawdown may reach 0.78 and 0.83 m, respectively. The results of this studies have shown that taking into account changes in petrophysical characteristics caused by hydrocarbon field development processes, tangibly changes the intensity of the deformation state of the rock massif and the earth surface above the deposit and, consequently, affects the level of geo-dynamic risk of oil-and-gas complex objects.