Zhu Shijie, Xue Xinsheng, Zhang Jian, Zhang Shilun, Liu Zhezhi
State Key Laboratory of Offshore Oil Exploitation, Beijing 100028, China.
Institute of Petroleum and Natural Gas Engineering, Chongqing University of Science & Technology, Chongqing 401331, China.
Polymers (Basel). 2022 Apr 26;14(9):1747. doi: 10.3390/polym14091747.
Polymer flooding is one of the most important enhancing oil recovery (EOR) technologies in the world. With the optimization of polymer synthesis, the performance of polymer solutions has been greatly improved, which can adapt to more complex oil and gas reservoirs. However, with the continuous improvement of the properties of polymer solutions, the elastic property of polymer solutions is significantly improved, and the rheological law has also changed. This series of changes affects the application of polymer flooding reservoir numerical simulation technology. Therefore, constructing an accurate description model and precise limitation conditions is particularly important. The rheological curve with a wide shear range (0.1~10,000 s) and the viscoelasticity of the two polymers (partially hydrolysed polyacrylamide (HPAM) and dendritic hydrophobic association polymer (DHAP)) were analyzed and tested by a rotating rheometer. The results showed that under the experimental conditions, the rheological curve of both polymers can be described by the Carreau rheological model. Meanwhile, the structural viscosity of the hydrophobically associating polymer solution (DHAP) greatly improved the elasticity of the solution and led to the change of elastic modulus. Considering the influence of elastic characteristics on the rheological curve, the relaxation time spectrum derived from small vibration experimental data was used to limit the characteristic relaxation time, that is, the value range of λ. It was observed that the experimental data were highly matched with the nonlinear regression fitting curve of the Carreau rheological model. Therefore, the relationship between different test parameters should be fully considered while studying the rheological constitutive equation of viscoelastic fluid, so as to optimize and improve the equation of it.
聚合物驱油是世界上最重要的提高采收率（EOR）技术之一。随着聚合物合成工艺的优化，聚合物溶液的性能得到了极大提升，能够适应更复杂的油气藏。然而，随着聚合物溶液性能的不断提高，其弹性性能显著增强，流变规律也发生了变化。这一系列变化影响了聚合物驱油藏数值模拟技术的应用。因此，构建准确的描述模型和精确的限制条件尤为重要。通过旋转流变仪对两种聚合物（部分水解聚丙烯酰胺（HPAM）和树枝状疏水缔合聚合物（DHAP））在宽剪切范围（0.1~10,000 s）内的流变曲线和粘弹性进行了分析测试。结果表明，在实验条件下，两种聚合物的流变曲线均可用Carreau流变模型描述。同时，疏水缔合聚合物溶液（DHAP）的结构粘度极大地提高了溶液的弹性，并导致弹性模量发生变化。考虑到弹性特性对流变曲线的影响，利用小振动实验数据导出的松弛时间谱来限制特征松弛时间，即λ的取值范围。结果发现，实验数据与Carreau流变模型的非线性回归拟合曲线高度匹配。因此，在研究粘弹性流体的流变本构方程时，应充分考虑不同测试参数之间的关系，以优化和改进该方程。
