Rheological Properties of Xanthan Gum, Hydroxypropyl Starch, Cashew Gum and Their Binary Mixtures in Aqueous Solutions

Large volumes of drilling fluids are used while drilling oil wells. Water-based fluids are widely used because they are generally less expensive and more environmentally correct than synthetic fluids. Polymers are used in drilling fluids with different functions. This article reports a study of the rheological behavior of solutions containing xanthan gum (XG), hydroxypropyl starch (HPS) and cashew gum (CG), as well as their binary mixtures, to evaluate the applicability of CG (an abundant product in Brazil's northeastern region) in aqueous fluid formulations. The results show the potential to use CG in mixtures with XG. The thixotropic effect is confirmed by hysteresis loop analysis; the rheological behavior is satisfactorily described by the Ostwald-de Waele and Casson models; the aqueous solutions containing XG/HPS mixtures present higher consistency indexes than the XG/CG mixtures; and the activation energy values of the XG/CG mixtures are governed by the CG fraction.