聚合物凝胶体系在孔隙介质中交联及运移封堵性能研究

Study of crosslinking and transport blocking properties of polymer gel system in porous media

聚合物凝胶体系是由部分水解聚丙烯酰胺和XL有机铬交联剂交联而成。采用ESEM2020型环境扫描电镜、聚合物凝胶动态交联和渗流规律实验装置及不同规格的填砂管模型对聚合物凝胶体系的微观交联机理、在孔隙介质中动态交联性能及在岩心中的封堵运移性能进行了研究。实验结果表明,聚合物分子在微观上呈星状结构排列,而聚合物凝胶在微观上呈链状分形结构,是Cr3+与聚丙烯酰胺分子中的羧基交联的结果。动态交联实验结果表明,聚合物凝胶体系在孔隙介质中流动状态下可发生交联,初始交联时间为7～8h,最终交联时间约为70h。聚合物凝胶体系在运移过程中,从填砂管前4个测压段的压力指数来看,各段压力系数均有不同程度的上升,说明聚合物凝胶体系具有良好的运移封堵能力;其在填砂管中的封堵系数随着注入孔隙体积倍数的增大而增大;但随着体系运移距离的增加,封堵能力降低。

The polymer gel is a cross-linking system consisted of partially hydrolyzed polyacrylamide HPAM solution and organic chromium (Cr3 +) crosslinker.ESEM2020 type environmental scanning electron microscopy,polymer gel dynamic crosslinking and seepage law experimental setup and unconsolidated sand model with different specifications are adopted for studying microcross-linked mechanism of polymer gel system dynamic cross-linking performance in porous media and transport blocking properties in rock cores.The experimental results show that the polymer molecules are arranged in star-shaped structure at the microcosmic view,and the polymer gel shows chain-like fractal structure microscopically,which is the result of cross-linking between Cr3+ and carboxyl group in polyacrylamide molecules.The simulation dynamic cross-linking experiment results show that the polymer gel can generate cross-linking under the flowing state of the porous medium,the initial cross-linking time is 7-8 h,and the final cross-linking time is about 70 h.The block coefficient of polymer gel during migration is as follows:the distribution in unconsolidated sand tube is increased with the rise of injected pore volume multiple;the main block is located at the entrance,the blocking strength is increased with the rise of the depth in system migration;from the pressure index of the former four manometry sections of the sand filling tube,the pressure coefficient of each section is increased to different degrees,which indicates that the polymer gel has good transport blocking ability.