A generalized model for field assessment of particle settling velocity in viscoelastic fluids

The accurate prediction of particle settling velocity in viscoelastic fluids is important for the design, analysis, and optimization of various oil-field operations including hole cleaning and cuttings transport in oil and gas well drilling, proppant transport in hydraulic fracturing operations. An experimental study was, therefore, conducted to investigate the effect of fluid viscoelastic properties on the particle settling velocity. The main objectives of the study were to understand the factors that influence the particle settling velocity in shear-thinning viscoelastic fluids and develop a generalized model for the field assessment of particle settling velocity in shear-thinning viscoelastic fluids. We prepared ten different fluids, which were divided into two groups based on their shear viscosity values. In each group, five fluids were having similar shear viscosity and variable elasticity values. Nineteen different spherical particles were used to conduct particle settling experiments with a density range from 2700 kg/m3 to 6000 kg/m3 and a diameter range from 1 mm to 4 mm. Rheological characterizations of the fluids have been conducted by using funnel viscometer, API Rotational viscometer, controlled shear rate, and amplitude sweep test measurements. The fluid elasticity was quantified by using the concept of energy dissipation, which is determined by using standard field measurements of the apparent viscosity (AV) and the funnel viscosity. Finally, based on the experimental results and theory of the particle settling in non-Newtonian fluids, we proposed a model that can be used for predicting particle settling velocity in shear thinning viscoelastic fluids. The statistical analyses have shown that the root means square error and mean absolute percentage error of model predictions were 0.0032 m/s and 4.1%, respectively.