The influence of temperature and inorganic salts on the rheological properties of xanthan aqueous solutions

Abstract

The rheological properties of xanthan gum in aqueous saline solutions and at increased temperatures are of great practical interest especially for its application in enhanced oil recovery during which the xanthan solutions are exposed to increased salt contents and relatively high temperatures. In this work, the influence of high temperature and high salt concentrations (up to 10 mass%) on the rheological properties of xanthan was investigated. The influence of three different salts was examined - NaCl, CaCl 2 and FeCl 3 . Five xanthan samples were used with the goal of comparing their rheological properties. Four of the samples were synthesized in the laboratory of one of the authors and one of them was a commercial sample (BAROID) used for enhanced oil recovery. The viscosity flow curves were determined for the investigated xanthan solutions and the obtained results showed that the rheological behavior of the laboratory prepared xanthan samples was very similar to the rheological behavior of the commercial sample. The investigated inorganic salts at concentrations as high as 10 mass% did not influence the viscosity of the xanthan samples, except Fe 3+ ion. Temperature had almost no influence on the viscosity in the investigated interval, especially at the higher shear rates. The shear dependent activation energies of viscous flow were calculated.