Abstract:

Polymer flooding has been applying in oil fields of China in large scale.Therefore it is very important to reinforce the theoretical research of polymer flooding.Polymer behavior of various slug sizes have been inves-tigated visually by magnetic resonance imaging (MRI)techniques.The core samples we used consist of three parallel permeability zones that simulate the geological structure of real fields formation.The 3-D magnetic resonance images of polymer slug movement in the core have been acquired,and pore utilization ratio variations have been studied in 3-D before and after polymer flooding.Research results show that the recovery of high permeability zone increased furtherly during polymer slug injection,and the effect of polymer injection in medium and low permeability zones were observed only after certain quantity of polymer was injected.However,the recovery of low permeability zone has increased a lot during water injection after polymer slug.The recovery in high and medium permeability zones increased a little at the same time.The 3-D NMR images show that pore utilization ratio in core dramatically increased after polymer slug injection,and this increase was related to the distance from pores to the influx.In heterogeneous samples,as polymer solution being injected,oil-water mobility ratio was raised.Microscopic and macroscopic water flooding sweep efficiencies were increased simultaneously.Therefore oil displacement efficiency was improved.

Key words: nuclear magnetic resonance, polymer, visualization, oil displacement efficiency, imaging technique

摘要：

采用核磁共振成像技术,在接近实际地层条件的三层非均质物理模型中,可视化地研究了不同大小聚合物段塞的驱油过程,获得了聚合物段塞运动的三维核磁共振图像,同时还研究了聚合物注入前后孔隙利用系数的三维变化情况.结果表明:聚合物段塞注入过程中,高渗层的采出程度得到进一步提高,注入一定体积的聚合物溶液后,中、低渗层才开始见效;聚合物段塞注入后的继续注水过程中,低渗层的采出程度有大幅度提高,同时,高、中渗透层也有所提高;三维核磁共振成像还表明,聚合物溶液注入后,模型孔隙利用系数明显提高,孔隙利用系数提高的幅度与孔隙注入端之间的距离有关;在非均质模型中,聚合物溶液能改善水油流度比,提高油层内部水驱微观波及系数和宏观波及系数从而提高驱油效果.

关键词: 核磁共振, 聚合物, 可视化, 驱油效率, 成像技术