羧甲基羟丙基黄原胶及其流变特性

为拓宽黄原胶的应用范围，采用环氧丙烷和氯乙酸钠在醇溶剂中与黄原胶（XG）反应制得淡黄色的羧甲基羟丙基黄原胶（CMHPXG）。对羧甲基羟丙基黄原胶的流变特性（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，0.5% CMHPXG溶液的表观黏度比0.5% XG溶液增大了3.35倍，且CMHPXG溶液的弹性模量、黏性模量和触变环面积均比XG溶液有显著的提高。陶粒在CMHPXG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。0.4% XG溶液在30℃的表观黏度为43.1 mPa·s，而0.4% CMHPXG溶液在120℃、170 s-1下剪切90 min后的保留黏度仍有64 mPa·s，CMHPXG溶液的耐温耐剪切性能相对XG有较大程度的提高。XG和CMHPXG溶液的流动曲线可用Cross本构方程进行表征，且模拟值与实验值吻合良好。相较于黄原胶，羧甲基羟丙基黄原胶的基本性能得到了较大幅度的提高。 

Carboxymethyl Hydroxypropyl Xanthan Gum and Its Rheological Properties

To broaden the application scope of xanthan gum, a carboxymethyl hydroxypropyl xanthan gum (CMHPXG) has been developed withepoxy propane, sodium chloroacetate and xanthan gum (XG) in alcohol solvent. The CMHPXG synthesized was studied for its rheological properties (shearing thinning characteristics, viscoelasticity and thixotropy) and its basic performance (sand carrying capacity, high temperature resistance and shearing resistance) as a fracturing fluid. The study showed that the apparent viscosity of a 0.5% CMHPXG water solution was 3.35 times of that of an XG water solution of the same concentration, and the CMHPXG solution had elastic modulus, viscous modulus and thixotropy loop area obviously greater than the XG solution. The settling velocity of haydite in CMHPXG solution was far less than that in XG solution, greatly improving sand carrying capacity of fracturing fluids. A 0.4% XG solution had apparent viscosity of 43.1 mPa·s, while a 0.4% CMHPXG solution, after being sheared 90 min at 120℃ and 170 s-1, had apparent viscosity of 64 mPa·s, indicating that CMHPXG had better high temperature resistance and shearing resistance. The flow curves of XG solution and CMHPXG solution can be characterized with Cross constitutive equation, and the simulated rheological values were well fitted with the experimental ones. Compared with xanthan gum, the CMHPXG developed has basic properties that are greatly improved.