小孔剩余油受力分析及数学模型的改进

FORCE ANALYSES OF THE REMAINED OIL IN THE SMALL PORES AND IMPROVEMENT OF THE MATHEMATICAL MODEL

在小孔剩余油物理模型的基础上,采用受力分析和压强分析的方法对其流动状态进行了研究,并对小孔剩余油数学模型进行了修正.结果表明,对于盲孔中静止的油滴,既可以将油滴视为一个“质点”,采用经典力学中受力分析的方法,也可以采用流体力学中压强分析的方法研究其赋存状态;对于间小孔中的油滴,应通过分析油滴两端的压强差,研究其赋存状态.对于盲孔中的油滴,当开口端注入水的压强发生改变时,油滴或膨胀或被挤压变形,加上惯性作用,一部分油滴突破盲孔,进入大孔道,被注入水带走;若盲孔的盲端被注入水压开,则盲孔变为连通孔隙,油滴被注入水驱替至大孔隙;对于间小孔中的油滴,当油滴两端注入水的压强发生改变时,油滴上、下两端压强平衡被打破,油滴被驱替至大孔道,被注入水带走.提出的盲孔中的油滴受力关系式、压强关系式和间小孔中的油滴压强关系式对周期注水等水动力采油方法有指导意义.

Based on the physical models of the remained oil in the small pores, the studies on the flowing states are conducted by means of the methods of the force and pressure intensity analyses, and furthermore the mathematical models are modified for this kind of oil. The results show that for the static oil droplet remained in the blind hole, it can be considered as a ＂particle＂, so the occurrence states of the droplet can be studied by both the force analy- sis which belongs to classical mechanics and the analyzing method of the pressure intensity which belongs to hydro- mechanics. For the oil droplet remained in the intergranular pore, the occurrence states of the oil droplet should be analyzed by means of the pressure differences between the two ends of the oil droplet. For the oil droplet in the blind hole, when the pressure intensity of the injected water changes at the open end of the blind hole, the oil drop- let will be swollen or deformed, and moreover with the help of the inertial effect, part of the oil droplet will break through the control of the blind hole and penetrate into the big channel and then is flooded away by the water injec-ted ~ if the blind end of the blind hole is fractured open by the water injected, the blind hole will be connected, so the oil droplet in it will be driven into the big channel. For the oil droplet located in the intergranular pore, when the pressure intensities changed at the two ends of the intergranular pore, the intensity balance at the two ends of the oil droplet is broken, thus the oil droplet will be driven into the big channels and flooded away by the water in- jected. The presented three relationships of the force and pressure intensity of the oil droplets in the blind hole and in the intergranular pore are significant for the guidances of the hydrodynamic oil-producing methods such as cyclic waterflooding and so forth.