IONIC TRANSPORT IN SWELLING SHALE

A model of hindered transport of solute in shale is described, and the n used to predict the radial flow of water and solute away from a well bore. Shale strata in the field may be assumed to extend to infinity, but laboratory tests are performed using finite samples of shale; both cases are studied. Osmotic effects can create transient changes in th e pore pressure (and total stress) which may lead to a disintegration of the drilled shale and mechanical instability of the wellbore.