多段塞平行聚能提高聚合物驱后采收率实验研究

Experimental study on multi-slugs parallel gathering energy for enhancing oil recovery after polymer flooding

聚合物驱后还有50%左右的剩余油,主要分布在聚合物未波及到的次一级孔隙中。通过依次注入不同黏度和性质的功能段塞,在不同渗透率区域形成均匀移动的驱油段塞,增大局部驱替压力梯度,挖潜中、低渗透区的剩余油。室内实验表明:注入多个轮次的功能段塞后,再进行水驱,原油采收率达到89.15%,比聚合物驱采收率提高32.78%。相比于其他开采技术,多段塞平行聚能驱油的产液含水率更低;三个岩心实验的产液量比率趋向于相近,并在较大范围保持稳定,窜流现象得到有效的抑制。在非均质实验中,中、低渗透层的含油饱和度分别下降了35%和56%,剩余油动用程度大幅提高,而高渗透层变化很小。两点压差随段塞向后推移而推移,局部压力最大值在段塞位移处,注入段塞在非均质油层近似平行移动。

About 50% oil was remained after polymer displacement and mainly distributed in the smaller pores of bypassed area by polymer displacement.The multi-slugs parallel gathering energy technology was developed,and its mechanism was described and identified in the paper.The plugging agents with different viscosity and quality were injected into three parallel cores to generate oil-displacement slugs in the different permeability zones,which could increase the partial displacement pressure gradient and oils remained in the middle and low permeability zones.The laboratory experiment showed that the oil recovery by water displacement after injecting two turns function slugs reached to 89.15%,which increased by 32.78% compared to the polymer displacement.The water-cut point of produced fluid was the lowest compared with the foam flooding,tri-combination flooding and polymer body expansion agent profiling.The produced fluid fractions of three parallel cores inclined to close and keep stable in a considerable extension,and the cross flow could be inhibited effectively.The heterogeneous experiment showed that oil saturations in the middle and low permeable zones decreased by 35% and 56% separately and changed little in the high permeable zone.Oil remained in the middle and low permeable zones could be employed greatly.The pressure difference changed with the movement of the injected slugs.The local pressure peak was located at the position of the slugs.The injected slugs approximately moved in parallel in the heterogeneous reservoir.