A model for clay filter cake properties

Abstract

Clay filter cake properties, such as porosity, compressibility and permeability, have been studied by means of a structural network model. The electric double layer repulsion and Van der Waals attraction forces together with the equilibrium conditions of the network structure are shown to be fundamental in simulating the properties of filter cakes. The factors which affect the properties of filter cakes, such as clay particle size, salt concentration, and surface charge density have also been investigated. Results from the model show that the porosity, compressibility and permeability are predictable functions of compression pressure. The porosity of a filter cake is very sensitive to the degree of aggregation of clay particles. The compressibility of filter cakes is most sensitive to the size of clay particles and to the salt concentration. Salt concentration is also a sensitive factor influencing the permeability of filter cakes and its dependence on applied pressure. The porosity, compressibility and permeability are obtained as a function of compression pressure and can be used in static or dynamic filtration calculations.