Borehole stability analysis in a thermoporoelastic dual-porosity medium

Rachel Gelet (1, 2) , Benjamin Loret (1) , Nasser Khalili (2)

1 3SR - Laboratoire sols, solides, structures - risques [Grenoble]
2 School of Civil and Environmental Engineering [Sydney]

The problem of diffusion and mass transfer in dual porous media is considered in a threephase framework. The solid phase is assumed to contain two distinct cavities filled with fluid. The porous mixture is composed of two overlapping media: the porous blocks and the fissure network. The fluid can transfer between the cavities due to fluid pressure difference. In addition, hydraulic and thermal diffusions take place through the mixture. A global understanding of mass transfer, diffusion and deformation is provided. The governing equations associated with these phenomena are presented for a mixture in thermal equilibrium. The finite element approximation of the governing equations is formulated and applied to the stability analysis of a vertical borehole. A parametric analysis is carried out to evaluate the influence of mass transfer on the pressure profiles of the fluids around the borehole. Permeable and a semipermeable boundary conditions are compared to predict the potential for failure of the wellbore under drained and partially undrained conditions.

Mots clés: thermo-poro-elasticity; dual porosity; thermal equilibrium; diffusion dominated flow; mass transfer; borehole stability

Domaines: Mécanique [physics]

Rachel Gelet, Benjamin Loret, Nasser Khalili. Borehole stability analysis in a thermoporoelastic dual-porosity medium. International Journal of Rock Mechanics and Mining Science & Geomechanics Abstracts, 2012, 50, pp.65-76. ⟨hal-00919454⟩