pH响应性预制凝胶颗粒的制备与溶胀性质

Preparation and swelling property of preformed particle gel with pH-responsiveness

关键词:  预制凝胶颗粒  溶胀  不稳定交联剂  缩醛  pH响应性 

Key words:  preformed particle gel  swelling  labile cross-linker  acetal  pH-responsiveness

摘要:

为实现CO₂驱油工艺中的深部波及控制,基于不稳定交联策略,设计了一种具有pH响应性质的预制凝胶颗粒。在同时引入酸性敏感型缩醛和稳定型双重交联剂的条件下,以丙烯酰胺为单体,通过溶液自由基聚合反应进行了制备。考察了缩醛含量、温度和介质pH值对其溶胀性质的影响,将制备的预制凝胶颗粒连续置于盐水和pH 值≤ 3.0的酸性缓冲溶液中后,表现出两级溶胀特性,而按常规方法制备的凝胶颗粒在同样条件下仅为单级溶胀模式。当稳定交联剂用量一定时,在两种介质中的平衡溶胀度均随缩醛用量的增加而降低。制备的凝胶颗粒在中性介质中的平衡溶胀度受温度影响较小,在酸性介质中溶胀速率和平衡溶胀度均随温度升高而增大。因此,这种具有pH响应性两级溶胀行为的预制凝胶颗粒对于实现CO₂驱油工艺中的深部波及控制将具有潜在的应用前景。

Abstract:

To realize the in-depth conformance control for CO₂-flooding process, a kind of preformed particle gel with pH-responsiveness was designed based on labile cross-linking strategy. The gels were prepared via solution radical polymerization of acrylamide as monomer, with the incorporation of an acid-labile acetal as cross-linker, in addition to a stable one. The influences of acetal content, temperature and media pH on the swelling behavior were investigated. The obtained particle gel was exposed to brine and acidic buffer(pH value≤3.0), then it showed the swelling pattern of two-stage, while the conventional preformed particle gels prepared under the same conditions showed a single-stage swelling pattern. With the same content of stable cross-linker, the equilibrium swelling degrees in the two media decreased with the increasing of acetal content. In the neutral medium, the equilibrium swelling degree was almost not influenced by the temperature, while the swelling rate and equilibrium swelling degree increased with the increasing of temperature in acidic media. Accordingly, this kind of pH-responsive preformed particle gel with two-stage swelling behavior would have potentials as promising materials for in-depth conformance control in CO₂-flooding processes.