Model development of permeability impairment due to clay swelling in porous media using micromodels

Swelling and displacement of clay minerals during drilling and production of oil and gas reservoirs are among the main mechanisms of formation damage. Most reservoirs contain clay minerals, either originally deposited during sedimentation phase, or precipitated from fluids flowing through matrix. Owing to the large specific surface area of clay particles, their swelling, detachment, and migrationmay lead to permeability impairment in porous media. Therefore, an accurate interpretation of the behaviour of clay particles in the porous media may enable us to prevent and possibly reverse the respective damage mechanisms. In this work, the pore-scale swelling behaviour of clays are studied using glass micro models as porous medium and Sodium bentonite as swelling clay. By image processing technique, effective porosity of model during low salinity water (LSW) flooding are estimated. The effect of different parameters such as porous medium aspect ratio and clay concentration on permeability impairment is studied. According to this study, besides higher clay concentrations, the permeability is also affected adversely by larger aspect ratio of pore bodies. Based on our experiments, a model is developed to estimate permeability impairment by clay swelling as a function of pore geometry and clay concentration.