| Summary: | Xanthan gum is a biopolymer used in several different industries for a variety of applications. In the Petroleum Industry, xanthan gum has been applied in Enhanced Oil Recovery (EOR) methods for mobility control due to its Non-Newtonian rheological behavior, relative insensitivity to salinity and temperature compared to other conventional synthetic polymers, as well as its environmentally-friendly characteristics. As challenging reservoir conditions arise, candidate polymers should meet the screening factors for high salinity, high temperatures and heterogeneous reservoirs. This paper aims to evaluate the effects of temperature and monovalent salts on the rheological behavior of xanthan gum for Enhanced Oil Recovery purposes. We tested polymer solutions with brine salinities of 20,000/110,000/220,000 ppm of Sodium Chloride in a rheometer at temperatures of 23, 50, and 77°C. The results acquired showed that temperature plays a key role in viscosity and salinity protected the solution viscosity against negative thermal effects, unusually a turning point is observed where the increase in the monovalent salt content enhanced the polymeric solution viscosity. Such investigations coupled with a detailed discussion presented in the paper contribute to understand critical aspects of xanthan gum and its capability to provide basic requirements that fit desired screening factors for EOR.
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