多重交联水凝胶体系的抗剪切性能评价研究

Evaluation of shear resistance of multi-crosslinked hydrogel system

凝胶调驱体系注入过程中的强剪切降解作用严重阻碍了施工应用效果,改善凝胶调驱体系的抗剪切性能,实现高效的深部调驱十分重要。通过对比疏水缔合聚合物(DHAP)与部分水解聚丙烯酰胺为主剂(HPAM)的多重交联水凝胶体系,开展抗剪切性、成胶性能、老化稳定性、封堵能力和调驱效果等内容研究。结果表明:疏水缔合聚合物在经历注入速度为175 mL/min的炮眼剪切后,黏度损失率仅4%,交联成胶后依然具备15 Pa·s的高强度,在多孔介质中的封堵率能够达到91%;在并联岩心驱替实验中,能够有效调驱,扩大对低渗岩心的波及效率,比HPAM为主剂的体系提高10%的原油采收率。通过适当降低共价交联密度,构筑的适度共价交联+非共价交联的水凝胶体系,能够在多孔介质中建立起较好的调驱作用能力。

The strong shear degradation in the injection process of gel profile control and flooding system has seriously hindered the effectiveness of construction application.It is very important to improve the shear resistance of gel profile control and flooding system and achieve highefficiency deep profile control and flooding.The multi-crosslinked hydrogel systems in which hydrophobically associating polymer(DHAP) and partially hydrolyzed polyacrylamide(HPAM) were used as the main agents were studied in the aspects of shear resistance,gel forming performance,aging stability,plugging ability and the effect of profile control and flooding.The results showed that the viscosity loss of DHAP was only 4% after being sheared by a blast hole with an injection rate of 175 mL/min,and high strength of 15 Pa·s was still obtained after crosslinking and gelling,and the plugging rate in porous media could reach 91%.In the parallel core displacement experiment,effective profile control and flooding could be achieved,the sweep efficiency of low-permeability cores was expanded,and the oil recovery was improved by 10% compared with the HPAM-based system.By appropriately reducing the covalent crosslinking density,the hydrogel system of moderate covalent crosslinking+non-covalent crosslinking could exhibit good ability of profile control and flooding in porous media.