低碳烃无水压裂液体系及流变特性研究

Low Carbon Hydrocarbon-based Fracturing Fluid Systems and Their Rheological Properties

侯向前 卢拥军 方 波 邱晓惠

HOU Xiang-Qian LU Yong-Jun FANG Bo QIU Xiao-Hui

用五氧化二磷、磷酸三乙酯和醇反应制得淡黄色的低碳烃无水压裂液胶凝剂二烷基磷酸酯。首次对正己烷、正辛烷、煤油、柴油四种烃代替水作为基液形成的凝胶体系的基本性能（携砂性、耐温耐剪切性）以及流变特性（黏弹性、触变性、剪切变稀性）进行了研究。结果表明，以柴油为基液、络合铁为交联剂，胶凝剂质量分数为1%时的最佳交联比（基液与交联剂质量比）为100:1.0，此时的凝胶黏度为177.26 mPa·s。陶粒在正己烷、正辛烷、煤油、柴油四种压裂液凝胶中静置4 h后的下降距离分别为8.0、5.0、4.5和8.0 mm，凝胶携砂性能良好。在100℃、170 s-1下剪切1.5 h，正己烷、正辛烷、煤油和柴油压裂液凝胶体系的保留黏度分别为16.9、229.5、293.6和324.3 mPa·s。随着基液碳链长度的增加，压裂液的耐温耐剪切性增强，弹性模量和触变环面积逐渐下降。四种凝胶体系在受剪切后均表现出剪切变稀特性，且随着基液碳链的增长，在相同剪切速率下，凝胶体系的黏度相对减小。不同烃基压裂液凝胶体系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。

The pale yellow gelling agent dialkyl phosphate ester was synthesized with triethyl phosphate, phosphorus pentoxide, and three alcohols as basic materials. The basic properties (proppant carrying capacity, temperature and shear resistance) and rheological properties (viscoelasticity, thixotropy, shear thinning) of the gel systems based on four kinds of hydrocarbons (n-hexane, octane, kerosene and diesel) instead of water were investigated for the first time. The results showed that the viscosity of diesel based gel was 177.26 mPa·s under proper conditions, such as 100:1.0 optimum crosslinking ratio, 1% gelling agent with iron complex as crosslinking agent. Four hours later, the descending distance of ceramsite was 8.0, 5.0, 4.5 and 8.0 mm in n-hexane, octane, kerosene and diesel based gel, respectively. At 100℃, the four fracturing fluids were sheared at 170 s-1 for 1.5 h, the reserved viscosity was 16.9, 229.5, 293.6 and 324.3 mPa·s for n-hexane, octane, kerosene and diesel based gel, respectively. The shear resistance and heat resistance of fracturing fluids intensified, and the elasticity modulus and the area of thixotropic loop decreased gradually with the growth of carbon chain of base fluid. Four gel systems possessed shear thinning property after shearing. At the same shear rate, the viscosity of each gel system decreased relatively with increasing carbon chain of base fluid. Non-linear co-rotational Jeffreys model could be applied to describe the flow curve of gel systems based on different hydrocarbons correctly and the calculated value was in good agreement with the experiment date.