Liang Li, Li Junlong, Li Dongxiang, Xu Jie, Zheng Bin, Zhao Jikuan
Key Laboratory of Optic-Electro Sensing and Analytical Chemistry of Life Science, Ministry of Education, Qingdao University of Science and Technology, Qingdao 266042, China.
Lab of Colloids and Functional Nanostructures, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.
Gels. 2025 Mar 31;11(4):256. doi: 10.3390/gels11040256.
To address the rapid crosslinking reaction and short stability duration of polyacrylamide gel under high salinity and temperature conditions, this paper proposes utilizing urea to delay the nucleophilic substitution crosslinking reaction among polyacrylamide, hydroquinone, and formaldehyde. Additionally, urea regulates the precipitation of calcium and magnesium ions, enabling the in situ preparation of an organic/inorganic composite gel consisting of crosslinked polyacrylamide and carbonate particles. With calcium and magnesium ion concentrations at 6817 mg/L and total salinity at 15 × 10 mg/L, the gelation time can be controlled to range from 6.6 to 14.1 days at 95 °C and from 2.9 to 6.5 days at 120 °C. The resulting composite gel can remain stable for up to 155 days at 95 °C and 135 days at 120 °C. The delayed gelation facilitates longer-distance diffusion of the gelling agent into the formation, while the enhancements in gel strength and stability provide a solid foundation for improving the effectiveness of profile control and water shut-off in oilfields. The urea-controlling method is novel and effective in extending the high-temperature cross-linking reaction time of polyacrylamide. By converting calcium and magnesium ions into inorganic particles, it enables the in situ preparation of organic/inorganic composite gels, enhancing their strength and stability.
为解决聚丙烯酰胺凝胶在高盐度和高温条件下交联反应迅速且稳定性持续时间短的问题，本文提出利用尿素来延缓聚丙烯酰胺、对苯二酚和甲醛之间的亲核取代交联反应。此外，尿素可调节钙镁离子的沉淀，从而原位制备由交联聚丙烯酰胺和碳酸盐颗粒组成的有机/无机复合凝胶。当钙镁离子浓度为6817 mg/L且总盐度为15×10 mg/L时，在95℃下凝胶化时间可控制在6.6至14.1天之间，在120℃下为2.9至6.5天。所得复合凝胶在95℃下可保持稳定长达155天，在120℃下为135天。凝胶化延迟有利于胶凝剂向地层中进行更长距离的扩散，而凝胶强度和稳定性的提高为提高油田调剖和堵水效果奠定了坚实基础。尿素控制法在延长聚丙烯酰胺高温交联反应时间方面新颖且有效。通过将钙镁离子转化为无机颗粒，能够原位制备有机/无机复合凝胶，增强其强度和稳定性。
