Radial Expansion of a Cylindrical or Spherical Cavity in an Infinite Porous Medium
V. M. Sadovskii1, O. V. Sadovskaya1, A. A. Luk'yanov2
1Institute of Computational Modeling, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, 660036 Russia
2Schlumberger Abingdon Technology Center, Abingdon OX14 1UJ, UK
Keywords: porous media, elasticity, plasticity, pore collapse unloading, pore expansion
Abstract
A solution describing the displacement and stress fields around expanding spherical and cylindrical cavities with allowance for pore collapse is constructed using the theory of small elastic deformations of a homogeneous isotropic porous medium in closed form. Transition of the medium into a plastic state is modeled using the Tresca-Saint Venant yield condition. Porosity change is described on the basis of a mathematical model developed taking into account the increase in the stiffness of the porous material at the moment of pore collapse. It is shown that in the elastic deformation stage, the porosity does not change; an increase in the pressure leads to the formation of a region of plastic compression, in part of which, the pores collapse. Stress and displacement fields in the porous medium during unloading are constructed. It is shown that under certain conditions, the elastic unloading stage is followed by the plastic reflow stage to form a region of pore expansion. As the pressure decreases, the boundary of this region simultaneously reaches the region of plastic reflow and the region of pore collapse.
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