DEFORMATION REGIMES OF FLUID-SATURATED RESERVOIRS UNDER SEISMIC IMPACT ACCORDING TO PRECISION HYDROGEOLOGICAL MONITORING DATA (A REVIEW)

A large volume of scientific papers is devoted to the study of the deformation mechanisms of fluid-saturated reservoirs. Precision hydrogeological monitoring data allows to objectively assess filtration properties of fluid-saturated reservoirs. The reaction of the «reservoir-well» system to atmospheric pressure, Earth tides and the propagation of earthquakes seismic waves can occur in the form of the groundwater level oscillations, coseismic and postseismic effects. Hydrogeological responses to quasi-stationary factors are determined by poroelastic deformation of the rock mass. Episodic seismic impact can lead to both poroelastic and inelastic reaction of a fluid-saturated reservoir. In the near-field zone of earthquakes, in the area of static stresses, an abrupt (step–like) change of permeability has been established, which may be associated with various mechanisms. These include liquefaction of dispersed soil, dilatancy – crack formation at the contact zone of rocks with different strength characteristics, and others. In the intermediate and distant zones, areas of dynamic stresses, long-period oscillations caused by the passage of shear and surface waves can lead to microcracks clogging/unclogging and variations of permeability. The formation of a holistic view of the deformation regime of a rock mass under seismic impact is aimed to predict possible changes of the fluid-saturated reservoirs filtration properties.