TRANSPORT OF SOLIDS IN A NON-NEWTONIAN ANNULAR VERTICAL FLOW OF BIOPOLYMER SOLUTIONS

This work presents an experimental study of solids suspension in upward annular flow using non-Newtonian biopolymer solutions as liquid phases. The biopolymers employed were xanthan and guar gums, and the solid phase consisted of silica sand with a mean particle size of 250 um. The experimental equipment is a vertical concentric pipe system, with 3 m of height and a hydraulic diameter of 0.15 m, simulating the drilling process at room temperature without the drill rotation effects. The annular velocity, concentration of load and polymer were the most important variables studied. It was found that the transport ratio allows a simple quantification of the effects of the polymer as a viscosifying additive in drilling muds, independently of the solids loading. xanthan gum provides a better suspension capacity than Guar gum_at similar concentrations, especially at low flow velocities, while at high velocities the solids transport is similar for both polymeric solutions, due to their pseudoplasticity.