The drilling of oil wells through shales, which constitute the majority of rocks in the stratigraphic column, may present instability problems due to physico-chemicals interactions between the drilling fluids and these rocks. The costs associated to the solution of these problems are very high and, depending upon the intensity of these problems, wells can be lost. In this thesis, a new equipment was developed which is capable of reapplying part of the stresses that were acting upon the rock sample. A testing methodology to evaluate rock-fluid interaction mechanisms and to determine the mass transport parameters, needed for wellbore stability analyses, is proposed. Specifically, parameters that describe the transport of water and ions due to hydraulic and chemicals gradients are determined. The knowledge about these parameters is instrumental to understand the efficiency of the drilling fluid in controlling instabilities during drilling. Tests carried out in two shales from offshore platforms using different fluids demonstrated the efficiency of equipment and of the testing methodology. The transport parameters obtained are consistent with values obtained elsewhere.