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为了研究聚合物溶液在多孔介质间长距离运移过程中黏度与黏弹性的变化规律,并确定其损失对驱油效率的影响,本文通过室内实验对聚合物驱进行了模拟。建立了30 m长填砂物理模型,在注入聚合物驱的过程中,于模型沿程不同位置分别采出样品,分析溶液表观黏度、聚合物分子量和浓度的变化规律。基于以上结果,配制与不同距离下采出液性质相同的聚合物溶液进行岩心驱油实验,并与同黏度丙三醇水溶液进行对比。实验结果表明,聚合物驱过程中溶液浓度和聚合物分子量随运移距离的增加而降低,基本满足线性规律;溶液黏度随距离的增加先快速下降,而后趋于平稳;储能模量在近井地带的损失非常严重。聚合物驱的驱油效率提高值随着运移距离的增大而逐渐降低,运移距离越远,聚合物溶液的提高采收率能力越弱,这与溶液黏度和黏弹性的损失密切相关,其中弹性损失对驱油效率的影响比黏性更为显著。该室内研究成果可为聚合物驱的优化设计提供一定的参考。
In order to study the variation of viscosity and viscoelasticity of polymer solution during the long-distance migration of porous media, and to determine the effect of its loss on displacement efficiency, the polymer flooding was simulated by laboratory experiments. A 30 m sand-filled physical model was established. Samples were collected from different locations along the model during injection of polymer flooding. The changes of apparent viscosity, polymer molecular weight and concentration were analyzed. Based on the above results, a polymer flooding solution with the same properties at different distances was prepared for core flooding experiments and compared with the same viscosity glycerol aqueous solution. The experimental results show that the solution concentration and the polymer molecular weight decrease with the increase of migration distance during the polymer flooding, which basically meets the linear rule. The solution viscosity decreases rapidly with the increase of distance and then tends to be stable. Well zone loss is very serious. The flooding efficiency of polymer flooding decreases gradually with the increase of migration distance. The farther the migration distance, the weaker the capacity of polymer solution to enhance recovery, which is closely related to the solution viscosity and the loss of viscoelasticity , Of which elastic loss has more significant effect on oil displacement efficiency than viscosity. The indoor research results can provide a reference for the optimal design of polymer flooding.