低渗透油层聚合物驱渗透率界限及驱油效果实验研究

Experimental Research on Permeability Limits and Displacement Characteristics of Polymer Flooding in Low Permeability Oil Layers

针对低渗透油层能否进行聚合物驱的问题,运用物理模拟方法开展了室内研究。渗流实验研究结果表明:对于低渗透油层,当孔隙喉道半径与聚合物分子回旋半径之比大于5倍时,注入低相对分子质量聚合物不会发生堵塞,小于5倍时会出现堵塞。驱油实验结果表明:聚驱比水驱提高采收率的幅度在3.79%～6.82%之间,平均5%左右。这说明低渗透油层可以开展聚合物驱,但由于受聚合物相对分子质量与低渗透油层渗透率匹配关系的限制,低渗透油层只能选用较低相对分子质量的聚合物,因此聚驱采收率提高幅度不大。

The displacement effect of polymer flooding in low permeability oil layers needs to be studied. With the application of physical analog, the lab study about polymer flooding is carried out. The results of filtrating flow experiments suggest: For low molecular weight polymer and low permeability oil layers, plugging will not occur when the ratio of pore throat radius to the gyral radius of polymer molecule is above 5, and plugging will occur when the ratio is less than 5. The displacement experiment results prove that the recovery factor of polymer flooding can be 3.79%-6.82% (5% in average) higher than that of water flooding. So, polymer flooding can be executed in low permeability oil layers. Due to the limit of the matching relationship between the relative molecular weight of polymer and permeability of low permeability oil layers, only lower molecular weight polymer can be selected for low permeability oil layers, and then the recovery factor improved for polymer flooding is not high.