弱凝胶深部调驱可视化驱油实验研究

针对人造岩心驱替过程不能直观展示以及大尺度三维模型工艺复杂和适应性差的问题,研制出一套能够在高温高压下进行不同渗透率岩心组合、模拟正反韵律储层,以及不同驱替方式的小尺度可视化装置。在注入0.3 PV弱凝胶型调驱体系,候凝24 h的条件下,研究不同时刻各相流体在多孔介质中的运移过程以及与人造岩心驱油实验结果对比分析。结果表明:在弱凝胶阶段,弱凝胶优先进入中高渗透层,减小层间非均质性,同时能够改变高渗层内部残余油的分布;在后续水驱阶段,低渗透层逐渐起主导作用,而且存在于大孔道的弱凝胶由于黏弹性,在驱替压力达到某一临界值时,弱凝胶能够在新的孔道内聚集,有利于弱凝胶在油藏深部进行深部调驱。与人造岩心驱油实验对比,可视化装置在含水率和采收率曲线的拟合度较高,说明可视化实验装置对进一步理解弱凝胶调驱机理具有指导意义。

Experimental Study on Visual Displacement of Deep Profile Control with Weak Gel

In view of the problem that artificial core displacement process cannot be displayed intuitively and the process of large-scale 3D model is complex and poor adaptability, developed a set of small-scale visualization devices capable of combining different permeability cores, simulating positive and inverse rhythm reservoirs, and different displacement methods under high temperature and high pressure. Under the conditions of injection of 0.3PV weakly gel modulated flooding system for 24h, the migration process of different phases of fluid in porous media at different times and the comparison with the experimental results of artificial core flooding were studied. The results show that in the weak gel stage, weak gel preferentially enters the medium and high permeability layer, reduces the heterogeneity between layers, and can change the distribution of residual oil in the high permeability layer, and in the subsequent water drive stage, the low permeability layer gradually plays a leading role. Because of viscoelasticity, weak gels in large pores can gather in new channels when displacement pressure reaches a certain critical value, which is beneficial to deep adjustment and flooding of weak gels in the deep part of reservoir. Compared with the artificial core flooding experiment, the visualization device has higher fitting degree in water cut and oil recovery curve, which indicates that the visual experimental device is of guiding significance for further understanding the mechanism of weak gel flooding.