微凝胶颗粒水分散液体系在多孔介质中的驱替机理

储层孔隙结构的非均质性导致水驱不均，不同大小孔隙（喉）之间形成优势渗流流动.在水驱开发中后期，剩余油高度分散在储层孔渗系统中难以启动，如何对孔隙尺度的水驱优势流动进行抑制的同时又确保不堵塞油流通道，使剩余油被高效采出，是当前提高石油采收率技术基础研究的主要方向.制作微观仿真储层孔隙结构与尺度的非均质性物理模型，开展了连续相驱替流体（聚合物溶液、交联聚合物凝胶）和微纳米柔性微凝胶颗粒水分散体系驱油机理的对比实验.实验表明，作为连续相的传统聚合物溶液依靠粘度无区分地增加大小孔隙中的流动阻力，从而赋予低渗层区小孔隙中的剩余油以驱动力，将这些剩余油携带采出，当粘度过大时，甚至难以启动剩余油；微凝胶颗粒分散液作为低粘水分散流体，其中的凝胶颗粒优先进入大孔隙，暂堵在喉道处并抑制相对大孔隙中的流动，同时注入水转向进入相对小的孔隙，将其中的剩余油活塞式推出，该过程在空间和时间上是不断重复的.本文从流度调整的角度对实验结果进行了分析，结果表明传统的连续相驱替流体是依靠提升注入水的粘度实现流度的调整，而微凝胶颗粒水分散体系是通过降低注入水的相对渗透率，并相对提高油相渗透率，从而实现对流度的高效调整. 

Oil Displacing Mechanism of Soft Microgel Particle Dispersion in Porous Media

The formation heterogeneity causes uneven sweeping of waterflooding. Different degrees of prevailing water flowing are generated due to different sizes of pores and throats. During the middle-late stage of water flooding, it is hard to move the remaining oil since it is scattered in the pores and throats. The EOR (enhanced oil recovery) study is mainly concerned with methods both to inhibit different sized prevailing flowing channels, and to keep oil flowing path free of plugging, which can ensure production efficiency of remaining oil. In this study, the pore-scale microscopic heterogeneous models with real pore structure were established, and different oil displacing mechanisms were compared between continuous phase viscous fluid, such as conventional polymer and crosslinked polymer gel, and micro-nano soft microgel particle dispersion. Results show that the traditional polymer flooding cannot differentiate between high and low permeability or big and small pore, because it relies on viscosity to increase the flowing resistance of all the swept area and it is hard to move the remaining oil when the viscosity is high to some extent. The soft microgel particle dispersion is a type of low viscosity dispersion fluid, and the particles have priority to access relatively big pore and throat, to temporarily inhibit the flowing, and at the same time, the water can be diverted into the relatively small pore and throat, to push the remaining oil out as a piston. The process is repeated continuously. The lab results were analyzed from the view of mobility adjustment in this paper, and it is concluded that the conventional continuous phase driving fluid modified mobility by increasing injection water viscosity, while the soft microgel particle dispersion achieved efficient mobility adjustment by decreasing the relative permeability of injection water and accordingly increased the oil permeable ability.