油藏大孔道内部形态结构既不同于多孔介质也不同于常见管道, 因此, 大孔道内流体流动规律也应不同于常规渗流及粗糙管流, 为方便表述, 本文定义流体通过大孔道的流动为“洞流”。为深入研究大孔道洞流规律, 以因次分析法为基础, 建立大孔道洞流规律物理模型的相似准数, 通过采用不同比例目数的砂粒, 制备了9 个大孔道洞流规律物理模型, 研究不同壁面突出度条件下大孔道的压降及流量关系。研究结果表明:随着流量的增加, 9 个不同突出度大孔道洞流物理模型的流体流动阻力压力梯度均随流量的增加而逐渐增大, 且突出度越大, 压力梯度的增幅越大;当流速增加到一定程度时, 大孔道洞流规律由线性流转变为非线性流;在相同横截面积及相同流动截面积条件下, 洞流的压降梯度小于渗流, 但大于粗糙管流。
关键词：
大孔道; 物理模拟; 洞流; 渗流; 管流
The inner morphological structure of large pore paths is different from neither porous media nor pipes, thus the fluid flow mechanism in them is different from seepage flow and pipe flow. This paper aims to study the law governing fluid flow in large pore paths in unconsolidated sandstone reservoir. The similar number of the physical models of large pore path fluid flow was established based on dimensional analysis. Nine physical models were established with different mesh numbers of sand grains to investigate the relationship between differential pressure and flow rate in large pore paths under different extruding conditions of walls. The results show that the pressure gradient of flow resistance in the nine psychical models increased with the increasing of flow rate, and the higher the extruding degree of the wall, the larger the amplification of the pressure gradient. When the flow rate was increased to a certain value, the fluid flow changed from linear to nonlinear. Fluid flow in large pore paths, porous media and pipes was compared under the same cross-sectional area and same flow cross-sectional area, and the pressure gradient in large pore paths was lower than that of seepage flow but higher than that of pipe flow.
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