聚合物、聚表剂和Cr~(3+)聚合物凝胶分子构型及其渗流特性差异

利用扫描电镜(SEM)、动态光散射(DLS)、流变仪和岩心驱替等实验方法研究聚合物、聚表剂和Cr3+聚合物凝胶的分子结构形态、分子线团尺寸、流变性、传输运移能力和渗流特性差异。结果表明:聚合物分子在水溶液中形成无规则的空间立体网络结构;聚表剂分子结构形态呈现片-网状结构;聚合物凝胶1发生以分子内为主、分子间为辅的交联反应,聚合物凝胶2发生以分子间为主、分子内为辅的交联反应;在相同质量浓度条件下,聚表剂分子线团尺寸最大,其次是聚合物凝胶2,再次为聚合物,聚合物凝胶1分子线团尺寸最小;聚表剂分子线团尺寸分布最分散,其次是聚合物凝胶1,再次为聚合物凝胶2,聚合物分子线团尺寸分布最集中;4种驱油剂均表现出先剪切增稠、后剪切变稀的流变特性,其中聚表剂剪切增稠和剪切变稀现象最明显;聚合物溶液传输运移能力最好,其次为聚合物凝胶1,再次为聚合物凝胶2,聚表剂溶液传输运移能力最差;聚合物凝胶残余阻力系数大于阻力系数,表现出独特的渗流特性。

Differences in molecular configuration and seepage properties among polymer, active polymer and Cr3+ polymer gel

The differences in molecular configuration, molecular coil dimension, as well as rheological and seepage properties among polymer, active polymer, and Cr³⁺ polymer gel were investigated by scanning electron microscopy (SEM), dynamic light scattering (DLS), rheometer and core flow experiment. The results show that a kind of stereoscopic random reticulation is formed when polymer molecules are dissolved in the water solution. The molecular structure of active polymer presents a flake-network configuration. For polymer gel 1 molecules, intra-molecular cross-linking is dominant with subsidiary inter-molecular cross-linking. However, for polymer gel 2 molecules, inter-molecular cross-linking is dominant with subsidiary intra-molecular cross-linking. At the same concentration, the molecular coil dimension (D_h) of active polymer is the largest, followed by polymer gel 2, then the polymer. And the D_h of polymer gel 1 is the smallest. The D_h distribution of active polymer is the most decentralized, followed by polymer gel 1, then the polymer gel 2. And the D_h distribution of polymer is the most centralized. Four oil displacement agents exhibit the rheological property of shear-thickening and followed by shear-thinning, in which the shear-thickening and the shear-thinning of active polymer are most significant. The migration capacity of polymer solution in the porous media is the greatest, followed by polymer gel 1, then polymer gel 2. And the active polymer is the worst. The residual resistance factor of polymer gel is bigger than the resistance factor, showing a kind of peculiar seepage characteristics.