The Effect of Fine Flocculating Particles and Fine Inerts on Carrier Fluid Viscosity

Design and maintenance of coarse-particle Newtonian slurries pipeline requires the knowledge of carrier fluid viscosity. Since measurements of carrier fluid viscosity are difficult, numerous empirical correlations are typically used to predict this value. The main deficiency of available correlations arises from the fact that the viscosity is predicted from the volume fraction of total fines. This approach neglects the different effects of various fines present in the suspensions (e.g., flocculating versus inert fines). In this study, idealized aqueous slurries consisting of inert silica (d ∼ 20 µm) and flocculating kaolinite clay were tested. A novel optical-based particle size analysis technique (FPIA) was commissioned to study flocculating and inert fines and estimate volume fraction of aggregates. Experimental data suggest that viscosity correlations are improved significantly if the volume fraction of aggregates is used as the primary correlating parameter, rather than the more conventional use of total fine solids volume fraction.