A gel based on polyacrylamide, exhibiting delayed crosslinking characteristics, emerges as the preferred solution for mitigating degradation under conditions of high temperature and extended shear in ultralong wellbores. High viscosity/viscoelasticity of the fracturing fluid was required to maintain excellent proppant suspension properties before gelling. Taking into account both the cost and the potential damage to reservoirs, polymers with lower concentrations and molecular weights are generally preferred. In this work, the supramolecular action was integrated into the polymer, resulting in significant increases in the viscosity and viscoelasticity of the synthesized supramolecular polymer system. The double network gel, which is formed by the combination of the supramolecular polymer system and a small quantity of Zr-crosslinker, effectively resists temperature while minimizing permeability damage to the reservoir. The results indicate that the supramolecular polymer system with a molecular weight of (268–380) × 10 g/mol can achieve the same viscosity and viscoelasticity at 0.4 wt% due to the supramolecular interaction between polymers, compared to the 0.6 wt% traditional polymer (hydrolyzed polyacrylamide, molecular weight of 1078 × 10 g/mol). The supramolecular polymer system possessed excellent proppant suspension properties with a 0.55 cm/min sedimentation rate at 0.4 wt%, whereas the 0.6 wt% traditional polymer had a rate of 0.57 cm/min. In comparison to the traditional gel with a Zr-crosslinker concentration of 0.6 wt% and an elastic modulus of 7.77 Pa, the double network gel with a higher elastic modulus (9.00 Pa) could be formed only at 0.1 wt% Zr-crosslinker, which greatly reduced the amount of residue of the fluid after gel-breaking. The viscosity of the double network gel was 66 mPa s after 2 h shearing, whereas the traditional gel only reached 27 mPa s.

中文翻译：

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超分子聚合物基双网络凝胶压裂液在超深层水力压裂中的应用

基于聚丙烯酰胺的凝胶具有延迟交联特性，成为在超长井眼高温和大剪切条件下减轻降解的首选解决方案。需要压裂液具有高粘度/粘弹性，以在胶凝前保持优异的支撑剂悬浮液性能。考虑到成本和对储层的潜在损害，通常优选较低浓度和分子量的聚合物。在这项工作中，超分子作用被整合到聚合物中，导致合成的超分子聚合物体系的粘度和粘弹性显着增加。超分子聚合物体系与少量锆交联剂结合形成的双网络凝胶，可有效抵抗温度，同时最大限度地减少对储层渗透率的损害。结果表明，由于聚合物之间的超分子相互作用，与0.6 wt%的传统聚合物相比，分子量为(268–380) × 10 g/mol的超分子聚合物体系在0.4 wt%的用量下可以达到相同的粘度和粘弹性。 （水解聚丙烯酰胺，分子量1078×10 g/mol）。该超分子聚合物体系具有优异的支撑剂悬浮性能，在0.4 wt%时沉降速率为0.55 cm/min，而0.6 wt%传统聚合物的沉降速率为0.57 cm/min。与Zr交联剂浓度为0.6 wt%、弹性模量为7.77 Pa的传统凝胶相比，只需0.1 wt% Zr交联剂即可形成具有更高弹性模量（9.00 Pa）的双网络凝胶，大大减少了破胶后液体的残留量。剪切2小时后，双网络凝胶的粘度为66 mPa·s，而传统凝胶仅达到27 mPa·s。