Network model for straining dominated particle entrapment in porous media

Abstract

A network model has been developed to study and describe formation damage resulting from particle entrapment in porous media by straining or size exclusion. Unlike the previous network models, this model considers the simultaneous entry of a number of particles into the network, as well as the effects of fluid flow on the particle transport path. A systematic study has been carried out on the flow and entrapment of monodispersed particles as well as particles with a size distribution through different networks. The effects of various parameters such as network size, particle size distribution and pore size distribution on the extent of formation damage, manifested by permeability reduction have been discussed in this paper. The model has also been used to determine the degree of prefiltration required to prevent damage to injection wells during water flooding. The model predictions show good agreement with experimental data for several different runs. A single parameter is used to match the exact number of pore volumes required to produce damage to the porous media. This parameter was found to be constant for the two different sandstones studied and for different concentrations of particles in the suspension. The simulation was also performed using the "random walk model" (which does not account for the fluid flow effects on particle flow) for purposes of comparison. The permeability responses predicted by this random walk model show trends that are significantly different from those observed experimentally. The network model developed in this paper has wide application in water flooding and matrix acidizing operations where diverting agents are used.