一种含PEO基双子表面活性剂压裂液的性能评价

Property Evaluation of a PEO Gemini Surfactant Fracturing Fluid

以丙撑基双[(十八烷基聚氧乙烯基)氯化铵](HY)为稠化剂、水杨酸钠为反离子盐配制了清洁压裂液,研究了该压裂液的黏弹性、变形恢复性能、携砂性能、耐温抗剪切性能及破胶性能。在60℃下,该清洁压裂液的黏度随稠化剂量的增加而增加,水杨酸钠加量为1%时的黏度达到最大值,较好的HY压裂液的配方为3%HY+1%水杨酸钠。压裂液中的稠化剂HY在反离子盐的作用下自组装成良好的三维网状结构。该压裂液具有良好的变形恢复能力,高剪切速率下压裂液的黏度迅速下降但随着剪切速率减小黏度几乎又全部恢复。HY压裂液在角频率0.03数100 rad/s时的弹性模量大于损耗模量,表现出较好的弹性特征。同时,该压裂液具有良好的耐温抗剪切性,在90℃、170 s^(-1)下剪切90 min后的黏度大于50 m Pa·s。HY压裂液的携砂性较好,在25℃和90℃下,携砂量30%时,石英砂在该压裂液中的沉降速率分别为0.075和15.25 mm/min。压裂液与煤油按体积比5∶1混合后在210 min左右破胶,黏度降至5 m Pa·s以下,破胶液表面张力为22.92 m N/m,界面张力为0.51 m N/m,残渣含量为56 mg/L,可满足现场施工要求。

PEO gemini surfactant fracturing fluid was developed using propylene-bis [ （octadecyl polyoxyethylene） ammonium chloride] （ HY for short ） as thickening agent and sodium salicylate （NaSal） as counter-ion salt, and its performances such as viscoelasticity, deformation recovery, suspending proppant capability, heat and shear resistance and gel-breaking were systematically investigated. The viscosity of the fracturing fluid increased with increasing HY content at 60 ℃, and the viscosity was the highest at the NaSal dosage of 1%, the optimal formulation of the fracturing fluid was 3% HY ＋ 1% NaSal. the thickening agent HY could form into a uniform three-dimensional network structure under the action of counter ion salt. HY fracturing fluid had good deformation recovery performance, and its viscosity decreased rapidly at high shear rate and was nearly superimposed in rate-decreasing direction. The storage modulus G＇ of the HY fracturing fluid was greater than loss modulus G＂ in the angular frequency region 0.03 -100 tad/s, exhibiting a very strong viscoelastic characteristic. Meanwhile, HY fracturing fluid had good heat and shear resistant property. The viscosity of the HY fracturing fluid was always higher than 50 mPa. s after sheared for 90 minutes at the temperature of 90℃ and at the shear rate of 170 s-1, which indicated that the HY fracturing fluid had good heat-resistance and shear-tolerance. The fracturing fluid had a better sand-carrying performance, and the settlement velocities of the sands （30%, v/v） in the fracturing fluid were 0.075 mm/min, 15.25 mm/min at 25℃ and 90℃, respectively. The viscosity of the HY fracturing fluid decreased below 5 mPa · s within 210 rains when mixing the HY fracturing fluid and the kerosene at volume ratio of 5 ： 1, and the surface tension of the breaker fluid was 22.92 mN/m while the interfacial tension between the breaker fluid and the kerosene was of 0.55 mN/m, and the residue content was of only 56 mg/L, indicating that HY fracturing fluid could meet the requirements of field operation.