Stability of a borehole drilled in a chemically active shale

This paper is concerned with the change in stress, pore pressure, and salt concentration taking place in a chemically active shale around a borehole filled with a drilling fluid which is not in thermodynamic equilibrium with the saturating fluid. We first derive a phenomenological Biot type theory of chemoporoelasticity. This theory can be degenerated into two limiting cases, one corresponding to the absence of any chemical interaction, and the other one which can be characterized as a perfect ion exclusion membrane theory. The equations are then specialized to solve initial boundary value problems, characterized by an irrotational displacement field. Finally, the Laplace transformed field equations are solved explicitly for the borehole problem.