Modeling the impact of the temperature profile on the sedimentation process for shear thinning suspensions in the annulus of oil well

Abstract

The particle settling phenomena were broadly studied in the literature experimentally and numerically. To the best of our knowledge, previous works do not consider the temperature effect on the suspension rheology and, consequently, the influence over the settling velocity. Motivated by the problem of the sedimentation in confined drilling fluids exposed to a geothermal temperature gradient, this work proposed a continuum model for the sedimentation process of weighting agents in non-Newtonian suspensions based on the Mixture Theory. A temperature-dependent correction for the suspension consistency index was proposed and the results were discussed for different temperature profile cases, including uniform temperature profile, linear and geothermal profiles. Numerical simulations were performed, using the Finite Volume technique. Results for the solids concentration along the column for up to five years were discussed as well as the solids concentration evolution for selected points along the column. The results showed that the temperature gradient significantly impacts the settling velocity and the evolution of sedimentation regions. The main affected zones were the free settling and the sediment zones, which can alter directly parameters of interest for applications in oil wells, such as the height of sediment.