摘要
考察了羟丙基磺基甜菜碱VESBET-4浓度、pH值和无机盐的加入对体系黏度的影响，并评价了VES压裂液（2.5%表面活性剂，3%无机盐，0.5%黏土稳定剂）的耐温抗剪切性能、携砂能力及破胶性能。结果表明：当转速达到250 r/min时，质量分数为2%的VESBET-4溶液的黏度可达到600 mPa·s以上；该表面活性剂适于在中性及碱性条件下使用；且该表面活性剂与黏土稳定剂NH4Cl、KCl具有良好的配伍性，无机盐的加入基本不影响体系的黏度。该压裂液体系具有良好的耐温耐剪切性能，在温度70℃、剪切速率170 s-1下的体系黏度仍高于50 mPa·s，60℃、170 s-1下剪切2 h后的体系黏度仍高于85 mPa·s。同时，单颗砾石的沉降速率为0.95 cm/h，砂比为30%时的砂子沉降速率为1.11cm/h，说明该体系具有良好的携砂造缝能力。使用模拟地层水可对该压裂液体系进行破胶，破胶时间在1h内，破胶后体系黏度可降至4.27 mPa·s以下。
Abstract
Several factors influencing the viscosity of the hydroxypropyl sulfo-betaine VESBET-4 solution relation, including the VESBET-4 concentration, pH value and the addition of inorganic salt (NH4Cl and KCl), were investigated, and the properies of the fracturing fluid composed of 2.5% surfactant, 3% inorganic salt and 0.5% clay stabilizer, such as the temperature tolerance and shearing resistance, prop-carrying capacity and gel breaking, were evaluated. The result demonstrated that the viscosity of VESBET-4 solution with mass fraction of 2% reached 600 mPa·s at a speed of 250 r/min. The surfactant VESBET-4 was suitable for use in neutral and alkaline conditions and had a good compatibility with clay stabilizers (NH4Cl and KCl), which almost had no influence on its viscosity. The fracturing fluid possessed good temperature tolerance and shearing resistance, the viscosity of the system was still higher than 50 mPa·s at the temperature of 70℃and the shearing rate of 170 s-1; and the viscosity of the system was still higher than 85 mPa·s after shearing for 2 h at the temperature of 60℃ and the shearing rate of 170 s-1. Meanwhile, the system had a good prop-carrying capacity, the settling velocity of single sand was 0.95 cm/h and when the sand ratio was 30% in volume settling velocity was 1.11 cm/h. The simulated formation water had been used to gel breaking, and the viscosity of the gel breaking liquid was lower than 4.5 mPa·s within 1 h.
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