基于动态共价键的自修复压裂液的制备及其性能

Preparation and Performance of Self-healing Fracturing Fluid Based on Dynamic Covalent Bond

黄志宇 郑存川

HUANG Zhiyu ZHENG Cunchuan

针对目前常用的冻胶压裂液难以同时抗高温和抗剪切的问题，设计了一种基于动态共价键的自修复压裂液，研究了该压裂液的抗剪切性能、抗温抗剪切性能、黏弹性能、携砂性能和破胶性能。研究表明，动态共价键交联自修复压裂液在高速剪切作用下能够动态修复，具有动态可逆的特性，表现出良好的自修复功能。自修复压裂液稠化剂基液黏度较低，有利于泵注。170 s-1剪切3 min后静置1 min循环3次，黏度保留率达到了97.6%；170s-1剪切2 min静置1 min再以510 s-1剪切2 min 静置 1 min循环剪切3次，黏度保留率达到65.7%；在120℃、170 s-1下剪切2 h，黏度保留率达到99.6%，表现出良好抗温抗剪切性能；并且在0.1-10 rad/s线性黏弹区范围内，自修复压裂液的弹性模量G?始终高于损耗模量G??。自修复压裂液具有良好的携砂性，相比胍胶压裂液携砂性能提高75%。自修复压裂液破胶后残渣含量几乎为零，对地层伤害小且易于返排。结果证明，将自修复凝胶应用于压裂液是可行的，同时也为压裂液的进一步研发提供了新的思路。

Aiming at the problem that the commonly used jelly fracturing fluids are difficult to resist high temperature and strong shear at the same time，a self-healing fracturing fluid（SHFF）based on dynamic covalent bonds was designed. The shear resistance， temperature and shear resistance，viscoelasticity，sand carrying capacity and gel breaking performance of the fracturing fluid were studied. The results showed that the dynamic covalent bond crosslinking SHFF could be dynamically healed under high-speed shear，and had the characteristics of dynamic reversibility，exhibiting good self-healing function. The viscosity of thickener base fluid of SHFF was low，which was beneficial to pump injection. After shearing for 3 min at 170 s-1 and then standing for 1 minutes for 3 times，the viscosity retention rate reached up to 97.6%，and the viscosity retention rate reached up to 65.7% after shearing at 170 s-1 for 2 minutes and then standing for 1 minutes followed by shearing at 510 s-1 for 2 minutes and then standing for 1 minutes for 3 times. The viscosity retention rate reached up to 99.6% when sheared at 170 s-1 for 2 h at the temperature of 120℃，which indicated that the SHFF had excellent temperature and shear resistance. In the range of 0.1—10 rad/s linear viscoelastic zone，the elastic modulus G' of the SHFF was always higher than the loss modulus G" of the SHFF. The SHFF had good sand-carrying performance，which was 75% higher than that of guar gum fracturing fluid. The residue content was nearly zero after the SHFF was broken，which indicated that the broken fluid had little damage to the formation and was easy to be flowed back. It is feasible to apply self-healing gel to fracturing fluid，and it also provides a new idea for the further research and development of fracturing fluid.