疏水缔合聚合物压裂液稠化剂LP-3A的研究

Study on a Hydrophobically Associating Polymer Viscosifier for Fracturing Fluids

采用反相乳液聚合方法,以AM、AMPS、带疏水链及聚氧乙烯基团的可聚合单体为原料,以过氧化苯甲酰(BPO)为引发剂,合成出新型疏水缔合聚合物稠化剂LP-3A。在室内通过单因素法得到了聚合反应最优单体比例、反应时间、反应温度、引发剂加量,并对LP-3A进行结构表征及耐温耐剪切性能、剪切恢复性能、黏弹性能、触变性能的研究。结果表明,LP-3A耐温耐剪切性能良好,在150℃、170 s^(-1)下剪切2 h,剩余黏度为200 mPa·s;剪切恢复率高,经过500 s^(-1)、1 000 s-1剪切20 min后,停止剪切的黏度恢复率为90%;黏弹性能及分子网络结构稳定性优于瓜胶压裂液,相比瓜胶,破坏LP-3A结构所需的能量较大,结构恢复所需的时间也较长,在LP-3A压裂液中弹性占主导地位,且黏弹性优于瓜胶压裂液。

A new hydrophobically associating polymer, LP-3A was synthesized through inverse emulsion polymerization, using AM,AMPS and monomers with hydrophobic chains and polyoxyalkylene groups as raw material, and benzoperoxide（BPO） as initiator.The polymerization conditions such as the optimum ratios of monomers, reaction time, temperature and initiator concentration etc.were determined through one-factor-at-a-time method. The molecular structure of LP-3A, a viscosifier used in fracturing fluids, was characterized, and the properties of LP-3A, such as temperature stability, shearing stability, recovery performance after shearing,viscoelasticity and thixotropy were studied. The study demonstrated that LP-3A had good high temperature stability and shearing performance. After being sheared under 150 ℃ and 170 s^-1 for 2 h, LP-3A still had residue viscosity of 200 mPa·s. After being sheared for 20 min at 500 s^-1and 1,000 s^-1, respectively, shearing was stopped, and 90% of the viscosity of the LP-3A solution can be recovered.Compared with guar gum, energy needed to destroy the network structure of LP-3A was higher, and time needed for the recovery of the structure was longer. In the LP-3A fracturing fluids, elasticity prevails, and the viscoelasticity of LP-3A fracturing fluids is superior to guar gum fracturing fluids.