黄原胶和瓜尔胶混合溶液及其硼砂交联体系的流变性能

本文研究了黄原胶(XG)和瓜尔胶(GG)的混合溶液及其硼砂(B)交联体系的流变性,考察了XG/GG间的“协同增效作用”以及溶液组成、pH和电解质(NaCl和CaCl 2)对其流变性的影响。结果表明,所有溶液体系均为假塑型流体,其流变曲线可用Herschel-Bulkley和Casson模型描述。XG和GG复配具有明显的“协同增粘效应”,在XG占两聚合物的质量分数w(XG)为20%和90%时协同增粘效应最强,其“协同增粘率”(R m)分别约为42%和34%。硼砂(B)可交联XG/GG混合溶液,其交联增粘效果随w(XG)的减小和硼砂质量浓度ρ(B)的增大而增大;在w(XG)=50%和ρ(B)=1.00 g/L时,“交联增粘率”可达85%。在所研究的pH值范围(6.2~10.0)内,XG/GG混合溶液的流变性基本无变化,而XG/GG/B交联体系(w(XG)=50%和ρ(B)=0.75~1.00 g/L)的表观粘度随pH值增大先升高后降低,pH=9.0时出现最大值,交联增粘率达107%。电解质可使XG/GG/B交联溶液(w(XG)=10%和ρ(B)=0.50 g/L)体系的粘度大幅下降,且CaCl 2的影响明显高于NaCl,表明交联结构的耐盐能力较差。这些结果加深了对XG/GG混合溶液流变性的认识,可为其实际应用(如在强化采油中的应用)提供依据。

Rheological Properties of Xanthan Gum/Guar Gum Mixed Solution and Its Borax-Crosslinked System

The rheological properties of xanthan (XG) /guar gum (GG) mixed solutions and their borax-crosslinked systems were investigated at a total solution concentration of 2.00 g/L. The synergistic interaction viscosification efficiency between XG and GG as well as the influence of solution composition, pH, and electrolytes (NaCl and CaCl₂) on the rheological properties were discussed. Under the studied conditions, all solution systems including pure XG, pure GG, and mixed XG/GG solutions as well as their borax-crosslinked systems behave as pseudoplastic fluids, and the rheological curves can be described by the Herschel-Bulkley and Casson models. The mixing of XG and GG exhibits a significant “synergistic viscosification effect”. When the mass fraction of XG in the two polymers (w(XG)) is 20% and 90%, maximum values of the synergistic viscosification rate (R_m) are observed, which are 42% and 34%, respectively. The XG/GG mixed solutions can be crosslinked by borax, and the crosslinking effect is enhanced with a decrease in w(XG) or an increase in borax mass concentration (ρ(B)). At w(XG)=50% and ρ(B)=1.00 g/L, the crosslinking viscosification rate (R) is up to 85%. In the studied pH range (6.2~10.0), there is no obvious change in the rheological properties for XG/GG mixed solutions, while for the borax-crosslinked systems (w(XG)=50% and ρ(B)=0.75~1.00 g/L), the apparent viscosity initially increases and then decreases, showing a maximum value at pH=9.0, and the corresponding R is up to ~107%. The addition of electrolytes (NaCl and CaCl₂) leads to a significant decrease in the viscosity for the crosslinked XG/GG/B solution (w(XG)=10% and ρ(B)=0.50 g/L), and the influence of CaCl₂ is more obvious than that of NaCl. These results may deepen the understanding of rheological behavior of XG/GG mixed solutions and provide important information for their practical applications such as in the enhanced oil recovery.