一种低浓度压裂液有机硼交联剂的合成与性能评价

Synthesis and Performance Evaluation of Organoboron Crosslinking Agent for Low Concentration Fracturing Fluid

针对目前国内压裂液稠化剂使用浓度较高的问题,以十水四硼酸钠为主原料,在NaOH的催化剂作用下,与乙二醇、三乙醇胺和多羟基醇进行络合反应,合成了适用于低浓度压裂液体系下的有机硼交联剂JS2-6,通过红外光谱对交联剂JS2-6以及HPG/JS2-6交联形成的冻胶分别进行了结构表征,研究了该交联剂与较低浓度的羟丙基胍胶所形成压裂液的延缓交联性能、耐温抗剪切性能、滤失性能、破乳性能和摩阻性能。通过实验得到的低浓度压裂液体系配方为:(0.3%~0.35%)HPG+0.2%杀菌剂FHS-18+0.2%助排剂F220+0.3%黏土稳定剂DS-208+0.1%交联促进剂+(0.02%~0.04%)p H调节剂,交联比为100∶(0.2~0.3),体系适用温度为60数150℃。通过调节体系的pH值,有效延长交联时间可达90 s。在温度140℃、剪切速率170 s^-1下剪切90 min,压裂液的黏度保持在150 m Pa·s左右,具有优异的耐温耐剪切性能。该体系在120℃时滤失系数最低为7.12×10^-4m/min^1/2,滤失量28 mL,能有效减少地层伤害。在120℃破胶后的破胶液与煤油间的界面张力<1 mN/m,破胶液黏度较低,对地层伤害率低,且具有低摩阻的特点,可达到易排液的使用要求。

In order to solve the problem of high concentration of fracturing fluid thickener in China,organic boron crosslinker JS2-6 was synthesized by using sodium tetraborate decahydrate as main material and complexing with ethylene glycol,triethanolamine and polyhydroxy alcohol under the catalysis of NaOH.The synthesized crosslinking agent JS2-6 was used in low concentration fracturing fluid system.The structure of crosslinking agent JS2-6 and HPG/JS2-6 was characterized by infrared spectroscopy.The delayed crosslinking,temperature and shear resistance,filtration,demulsification and friction properties of the fracturing fluid formed by the crosslinking agent and low concentration hydroxypropyl guanidine gum were studied.The formula of low concentration fracturing fluid system obtained by experiment was as follows:0.3%-0.35%HPG+0.2%fungicide FHS-18+0.2%assistant F220+0.3%clay stabilizer DS-208+0.1%cross-linking accelerator+0.02%-0.04%pH regulator,the cross-linking ratio was 100∶(0.2-0.3),and the suitable temperature of the system was 60-150℃.The crosslinking time could be prolonged up to 90 s by adjusting the pH value of the system.After sheared for 90 minutes at the temperature of 140℃and shearing rate of 170 s^-1,the viscosity of the fracturing fluid remained about 150 mPa·s,which indicated that the fracturing system had excellent temperature and shear resistance.The system had the lowest filtration coefficient of 7.12×10^-4 m/min^1/2 and a filtration capacity of 28 mL at 120℃,indicating that the system could effectively reduce formation damage.The interfacial tension between gel breaking fluid after gel breaking and kerosene at 120℃was less than 1 mN/m,in addition,the gel breaking fluid had low viscosity,low formation damage rate and low frictional resistance,which could meet the requirements of easily draining.