Geomechanical and Hydrodynamic Fields in Producing Formation in the Vicinity of Well with Regard to Rock Mass Permeability-Effective Stress Relationship

The nonlinear model is developed to describe geomechanical and hydrodynamic fields in the vicinity of a vertical well in a fluid-saturated formation for the case when the permeability k depends on the effective stress σ f by the exponential law. The analytical solutions are obtained for the porous-elastic and porous-elastoplastic modes of deformation of the well vicinity, based on which the change in the pressure and rate of flow under the variation of parameters characterizing the dependence k ( σ f ) is analyzed. It is found that the rate of flow exponentially decreases with an increasing horizontal stress of the external field; the permeability of the irreversible strain zone around the well decreases with the distance from the well boundary. The test scheme is proposed for permeability of samples with the center hole under side loading, and the experimental data interpretation procedure is put forward, which enables finding the empirical dependence k ( σ f ).