Colloid Chemistry of In-Situ Clay-Induced Formation Damage

Abstract

Abstract Clay induced formation damage in the vicinity of injection and disposal wells is a worldwide problem in the petroleum industry. The physical chemistry and dynamics of the internal clay transport are still poorly understood issues. In this paper we give a comprehensive theoretical overview over effect of the main physico-chemical factors on the stability and transport of clay particles in sandstone porous media and their influence on the rock permeability. First we give a short "reservoir oriented" introduction to the DLVO theory (Derjagin – Landau – Verwey – Overbeek) which makes it possible to quantify the interactions between clay particles and the rock matrix in terms of electrostatic repulsive and Van der Waals attractive forces. Secondly, we explain the mechanisms of clay surface charge formation. Than we describe the structure of the electrical double layer around clays. Subsequently we consider in detail the influence of hydrodynamic and physico-chemical factors on coagulation –dispersion of clay particles in sandstone. In particular we describe the effect of interstitial velocity, chemical composition, pH, and temperature of the permeating fluid, as well as clay mineralogy, micromorphology, and composition of the exchangeable cations. Furthermore we describe the effect of structural forces on clay stability, which are often ignored in the petroleum literature. Finally we consider the influence of rock microstructure and clay micromorphology on sandstone water sensitivity.