Rheological double-porosity model for clayey rocks

Abstract

We examine a unified mathematical model of rheological and transport properties of saturated deformable fractured rocks and clays. The foundation of the model is the unification of filtration consolidation theory and the theory of stability of lyophobic colloids for the case of clay's deformations, which is based on the concept of disjoining pressure as surplus in comparison with hydraulic pressure, caused by the surface capacities and existing in water films between clay particles. We analyzed the approximate solution about wringing the water out of the layer. The solution that we received demands us to introduce a concept of limit shear stress for clays. We investigate the peculiarities of the model, which are important for explaining some characteristic features of mass transport processes in deformable rocks (the existence of special filtration regime in fractured rocks) and transfer processes in clays (the existence of anomalous high pressures in not compressed clays, the flocculation at diffusion in clays, etc.). It is shown that the solutions that we have derived are in good agreement with results of experiments.