The swelled clay shrinkage property and inhibition of microcosmic migration in pores of quaternary ammonium salt cationic polymer

In the low permeability and high water-sensitive reservoir, water injection may induce the clay minerals hydration swelling and dispersing migration, which are the main factors for formation damages. Sodium montmorillonite, which is easier to hydrate in water than other clay minerals, is usually used to analyze the hydration of clays. A quaternary ammonium salt cationic polymer was synthesized and used as a clay stabilizer. The stability of sodium montmorillonite by interaction with the quaternary ammonium salt cationic polymer was studied, and the swelled clay shrinkage property of the quaternary ammonium salt cationic polymer was also analyzed and assessed by using the XRD, ESEM and visual micro-lithography model from microcosmic points. The results show that the interplanar spacing of hydration swelling sodium montmorillonite observed by XRD decreased as the quaternary ammonium salt cationic polymer infiltrated into the clay and replaced exchangeable cations. ESEM observations show that the sodium montmorillonites were wrapped by quaternary ammonium salt cationic polymer because of the network structure, which could make the size of the hydration swelling sodium montmorillonites smaller. The visual micro-lithography models confirmed that the clays were wrapped by the quaternary ammonium salt cationic polymer. The hydration swelling and dispersing migration were thus inhibited. Considering the experimental results, this quaternary ammonium salt cationic polymer can play a significant effect on the inhibition of clay hydration swelling and dispersing migration. Copyright (C) 2015 John Wiley & Sons, Ltd.