用于CCUS地质封存的CO₂响应型智能凝胶封窜体系

CO₂ Responsive Smart Gel Sealants for CCUS Geological Storage

刘琦 赵莉 马忠诚 刘子龙 彭勃

LIU Qi ZHAO Li MAZhongcheng LIU Zilong PENG Bo

为了有效应对封存CO2后可能会发生的泄漏或逃逸，制备了一种注入性优良、封堵效果良好的CO2响应型 凝胶，在酸性条件下发生溶胶-凝胶态转变，适用于CCUS地质封存条件以提高井筒完整性。研究了不同的支化 聚乙烯亚胺用量（1.5%～3.5%）、κ-卡拉胶用量（0.4%～0.5%）下CO2响应型智能凝胶体系的流变性能、微观结构 与封堵性能。研究表明，对于响应前的聚合物体系，剪切黏度随着剪切速率的增加而下降，为假塑性流体，当剪 切速率在100～1000 s-1时，黏度为2～100 mPa·s，表明响应前的聚合物体系具有良好的注入性。该聚合物体系 遇到CO2时会发生溶胶-凝胶态转变。响应前聚合物体系在剪切频率为0.01～10 Hz时，模量在10-5～100 Pa 范围 内；而CO2响应凝胶在剪切频率为0.01～10 Hz时，模量在80～4000 Pa 范围内，通入CO2气体后的体系模量大幅 度提升。发生响应后，体系具有表面平整、孔径均匀的三维网络骨架结构，使得体系具有较高的强度。岩心驱替 实验结果显示F 凝胶封窜体系（κ-卡拉胶用量为0.5%，支化聚乙烯亚胺用量为3.5%）对CO2气体的封堵率为 79.7%，对后续注入水的封堵率为99.8%，具有良好的封窜性能。本文为未来CO2响应型凝胶封窜剂在CCUS地 质封存领域的应用提供了新的技术路线与理论依据。

In order to effectively deal with the leakage or escape that may occur after CO2 storage，a CO2 responsive gel with excellent injectability and good sealing effect was prepared. The sol-gel state transition occurs under acidic conditions，which was suitable for CCUS geological storage conditions and could improve wellbore integrity. The rheological properties，microstructure and sealing performance of CO2 responsive gel with different amounts of branched polyethyleneimine （1.5% —3.5%） and κ-carrageenan（0.4%—0.5%）were studied. The study showed that the viscosity of the system before the response decreased with the increase of the shear rate，and the system was a pseudoplastic fluid. When the shear rate was 100—1000 s-1，the viscosity was 2—100 mPa·s，indicating that the system had good injectability. The polymer system undergoed a sol-gel state transition when it encountered CO2. The modulus of the pre-response system was in the range of 10-5 —100 Pa when the shear frequency was 0.01—10 Hz；while the modulus of the CO2 responsive gel was in the range of 80—4000 Pa when the shear frequency was 0.01—10 Hz. The modulus of the system after the introduction of CO2 was greatly improved. After the response，the system had a three-dimensional network skeleton structure with smooth surface and uniform pore size，so that the system had high strength. The results of the core flooding experiment showed that the plugging rate of the F system（the amount of κ-carrageenan was 0.5%，the amount of branched polyethyleneimine was 3.5%）for CO2 gas was 79.7% and the plugging rate for the water phase was 99.8%，exhibiting good anti-gas channeling performance. This paper provided a new technical route and theoretical basis for the application of CO2 responsive gel channeling agent in the field of CCUS geological storage in the future.

10.19346/j.cnki.1000-4092.2022.04.009