阳离子黄原胶的合成及性能评价

Synthesis and Property Evaluation of Cationic Xanthan Gum

为提高黄原胶的基本性能并拓宽其应用范围,将阳离子醚化剂(3-氯-2-羟丙基三甲基氯化铵)和黄原胶(XG)在碱性条件下反应制得淡黄色的阳离子黄原胶(CXG),对CXG的流变特性(剪切变稀性、黏弹性、触变性)以及其作为压裂液的基本性能(携砂性、耐温耐剪切性)进行了研究。结果表明,6 g/L CXG溶液的表观黏度比XG溶液增大了1.34倍,且CXG溶液的弹性模量G'、黏性模量G''和触变环面积均比XG溶液有显著的提高;陶粒在CXG溶液的沉降速度远小于在XG溶液的沉降速度,携砂性能得到提高;XG改性后的耐温耐剪切性提高,4 g/L CXG溶液在80℃、170 s^(-1)下剪切90 min后的保留黏度为58.05 mPa·s,与同浓度的XG溶液在30℃的表观黏度(47.53 mPa·s)相当;XG和CXG溶液的流动曲线可用非线性共转Jeffreys本构方程进行表征,且模拟值与实验值吻合良好。XG通过阳离子改性后,基本性能得到了较大幅度的提高。

In order to improve the basic performance of xanthan gum and widen its application, cationic xanthan gum （CXG） with bright yellow was synthesised by xanthan gum （XG） and cationic etherification agent （3-chloro-2-hydroxypropyltrimethyl ammonium chlorid） under alkaline condition. The rheological properties of CXG, including shear thinning, viscoelasticity and thixotropy, and the basic properties of CXG solution as fracturing fluid, including proppant carrying capacity, temperature and shear resistance were studied. The results showed that the apparent viscosity of 6 g/L CXG solution was 1.34 times more than that of 6 g/L XG solution. The storage modulus G＇ and the loss modulus G＂ of CXG solution were greater than those of XG solution, and viscoelastic and thixotropic properties were more significant in CXG solution. The descending velocity of ceramsite in CXG solution was much less than that in XG solution. The reserved viscosity of 4 g/L CXG solution was 58.05 mPa. s after sheafing at 80℃ and 170 s-- for 90 minutes, while the apparent viscosity of 4 g/L XG solution at 30℃ was only 47.53 mPa. s, indicating that the modification of XG enhanced the temperature and shear resistance of XG. Non-linear co-rotational Jeffreys model could be applied to describe the flow curve of XG and CXG solution correctly and the calculated values were in good agreement with the experiment values. Compared with XG, the basic performance of CXG was improved dramatically.