特低渗透储层提高水驱油效率实验研究

Experimental study on enhancing oil displacement efficiency of waterflooding in ultra-low permeability reservoir

西峰油田长 8储层渗透率低 ,物性差 ,属特低渗储层 ,常规注水驱油效率低 .在注入水中加入表面活性剂后 ,最终驱油效率比水驱有较大幅度的提高 ( 2 6.6% ) ;水驱压力同样对特低渗透储层岩心驱油效率有显著影响 ,对于空气渗透率大于 1× 1 0 -3 μm2 的岩心 ,水驱压力的提高使水相相对渗透率大幅上升 ,即储层容易发生水窜 ,导致驱油效率上升不多或下降 ;对于空气渗透率小于 1×1 0 -3 μm2的岩心则相反 ,水驱压力的提高不会导致水相相对渗透率上升 。

Chang-8 reservoir in Xifeng oilfield is of very low permeablity, and the oil displacement efficiency of traditional waterflooding is extremely low. The experimental results in this paper show that, after adding surfactant to injected water, the final oil displacement efficiency of two cores is increase by 26.6% on the average, and that water injection pressure has remarkable effect on oil displacement efficiency in ultra-low permeable reservoir. For the core whose air permeability is higher than 1×10^(-3)μm^2, oil displacement efficiency decrease when water injection pressure rises; for the cores whose air permeability is lower than 1×10^(-3)μm^2, oil displacement efficiency increase when water injection pressure rises. On the average, the permeability of Chang-8 reservoir is lower than 1×10^(-3)μm^2,and therefore rising water injection pressure can increase its oil displacement efficiency.