渗透率级差对聚合物驱产液指数的影响

Effect of Permeability Level Difference on Polymer Production Liquid Index

储层层间物性差异是影响非均质油藏聚合物驱采收率的重要因素。为揭示由水驱转为聚合物驱过程中的产液指数的变化规律,通过物理模拟实验研究了岩心渗透率级差对聚合物驱产液指数的影响。结果表明,由水驱转为聚合物驱的过程中,产液指数变化整体上经历水驱上升段、聚合物驱速降段、聚合物驱缓降段以及聚合物驱回返段四个阶段;在非均质岩心实验中,储层渗透率级差变化对聚合物驱阶段的产液指数下降幅度具有明显影响,具体表现为聚合物注入后产液指数、采收率随渗透率级差的增大而减小。研究结果对于判定存在储层渗透率级差油藏的聚合物驱合理产液下降幅度、预测产液下降周期具有一定的指导意义。

The difference of physical properties between heterogeneous reservoirs is an important factor affecting the recovery of polymer flooding. Focusing on the varying pattern of liquid productivity index in the process of water flooding to polymer flooding, the variation of liquid productivity index in different permeability ratio were studied with physical simulation experiment. The experimental results showed that there were four phases for the liquid productivity index in the process of water flooding to polymer flooding： water flooding increasing phase, polymer flooding rapid decreasing phase, polymer flooding gradually decreasing phase and polymer flooding increasing phase. In the heterogeneous core flooding experiment, the change of reservoir permeability ratio difference had obvious effect on the decrease of the liquid production index in the polymer flooding stage, the liquid production index, oil recovery decreased with the increase of the permeability ratio. The experimental results could afford a guide for the reasonable estimation of polymer flooding liquid production decreasing range and the forecasting of polymer flooding liquid production decreasing period.