Chapter 12 - Cake Filtration: Mechanism, Parameters and Modeling

Abstract

Models for the interpretation and prediction of incompressible and compressible filter-cake thickness, as well as filtrate volume and rate data for linear and radial filtration cases, under static and dynamic filtration conditions, are presented. Effects of compressibility and small particle invasion and deposition inside the cake and formation, as well as the Darcy versus non-Darcy flow regimes, are considered. Methods and diagnostic charts for determining the model parameters from experimental filtration data are reviewed. Applications for radial and linear filtration cases are presented, and the results are compared for constant rate and constant pressure drive filtration. Model assisted analyses of experimental data demonstrate the diagnostic and predictive capabilities of the models. The parametric studies indicate that the particle screening efficiency of the formation is an important factor on the filter-cake properties and filtration rate, the differences between the linear and radial cake filtration performances are more pronounced, and the cake thickness and filtrate volume are smaller, for constant pressure filtration than constant rate filtration. The present thickness-averaged ordinary differential models are shown to reproduce the predictions of the previous partial differential model rapidly with significantly less computational effort. Because of the simplicity of the equations and reduction of computational effort, the thickness-averaged linear and radial filter-cake formation models offer significant advantages over the partial differential models for the analysis, design, and optimization of the cake filtration processes involving the wellbore and hydraulically created fracture surfaces. Simplified models considering incompressible particles and carrier fluids, and analytical solutions for incompressible cakes without fines invasion are also presented. These models provide insight into the mechanism of cake filtration and offer practical means of interpreting experimental data, estimating the model parameters, and simulating the linear and radial filtration processes.