A study of the behaviour of viscoelastic fluids in constant pressure filtration.

Abstract

A filtration theory for constant pressure filtration in viscoelastic media is presented. The theory is based on the linearized capillary hybrid model for flow in a porous medium. The main filtration equation is quite similar to that for non-Newtonian filtration except for the parameter $v\sb{me}$ representing a sum of two terms: one term characterizing the viscous (Newtonian) nature of the flow, and the second term portraying the elastic contribution to the flow. Constant pressure filtration experiments are performed using slurries of calcium carbonate in aqueous solutions of high molecular weight polyacrylamide (viscoelastic slurries) and slurries of calcium carbonate and water (Newtonian slurries). Three pressure drops are employed: 345 kPa, 517 kPa, and 689 kPa. The filtration theory provides a means to compile the experimental data, wherein filter cake and filter medium resistances are computed and compared. It is found that the filter cake resistances of the viscoelastic filtrations were considerably lower than those of the Newtonian filtrations. Furthermore, the filter medium resistances of the viscoelastic filtrations were, in general, higher than those of the Newtonian filtrations.