Permeability Evolution During Cyclic Loading and Colloids Migration

The irreversible deformation of the pore space, which can occur under dynamic loads as well as creep, is widely accepted as the primary cause of the porous rock’s permeability hysteresis after cyclic loading. However, in most pore-mechanical works, no attention is paid to the method of measuring permeability. When loading rocks, apparent permeability, which characterizes the direct transport properties of rocks, is measured by injection of fluid or gas. When a fluid or gas is injected into a porous medium, colloid migration can occur, contributing to pore channel blocking and a decrease in permeability. This effect receives little attention, which can lead to an incorrect representation of the change in permeability during loading, including cyclic loading. Only a few theoretical and experimental works are devoted to the combined effect of colloids migration and loading on transport properties of porous media, while separately these reasons are studied in sufficient detail. The results of core plug tests are presented in this paper. It has been established that the apparent permeability of samples changes under load due to both mechanical compaction and colloid migration. The research methodology eliminates the influence of reactive flow minimizes and possibility of irreversible deformations. The only reason for the change in apparent permeability during forward and reverse injection is colloidal migration, which is confirmed by indirect methods.