Damage Characterization of Deep Bed Filtration from Pressure Measurements

Abstract

AbstractPermeability decline occurs during injection of sea or produced water, resulting in well impairment. Solid and liquid particles dispersed in the injected water are trapped by the porous medium and may increase significantly hydraulic resistance to the flow.We discuss a mathematical model for deep bed filtration containing two empirical parameters – filtration coefficient and formation damage coefficient. These parameters should be determined from laboratory coreflood tests by forcing water with particles to flow through core samples. A routine laboratory method determines the filtration coefficient from expensive and difficult particle concentration measurements of the core effluent; then the formation damage coefficient is determined from inexpensive and simple pressure drop measurements.An alternative method would be to use solely pressure difference between the core ends. However, we have proved in earlier work that given pressure drop data in seawater coreflood laboratory experiments, solving for the filtration and formation damage coefficients, is an inverse problem that determines only a combination of these two parameters, rather than each of them.A new method for the simultaneous determination of both coefficients is developed here. The new feature of the method is that it uses pressure data at an intermediate point of the core, supplementing pressure measurements at the core inlet and outlet. The proposed method furnishes unique values for the two empirical coefficients, and the solution is stable with respect to small perturbations of the pressure data.In the current work the proposed method is used for analysis of laboratory test data on deep bed filtration. The values of filtration and formation damage coefficients are obtained for flow of solid and liquid particle dispersions in a number of different cores. Effects of particle type and porous media wettability on permeability decline are analyzed.