泡沫在孔隙介质中的微观流动特征研究

Study on Microscopic Flow Characteristics of Foam in Porous Media

泡沫在孔隙中的流动行为影响波及范围和驱油效率,对提高采收率起到重要作用。首先,建立单毛管模型,利用Level-set方法研究了泡沫在单毛管内流动的影响因素,分析了泡沫通孔隙介质中运移产生的贾敏效应、聚并机理和微观选择性运移机理,评价了不同类型泡沫的封堵性能;然后,通过XB油田岩芯的CT图像构建了真实的孔隙介质微观数值模型,研究了泡沫在其中的运移特点。结果表明,泡沫变形程度随管径比的增大而减小,润湿壁接触角对毛细管内泡沫的流变性无影响,半径1.2μm的N_(2)泡沫破裂时的液相流速临界值为64 mm/s;泡沫通过孔道时所受压力与其表面张力成正比,泡沫具有优先通过大孔道的微观运移特征;N_(2)泡沫稳定性强,封堵性能好,较适合高含水期的低渗油田进行调驱,为现场采用气液分散体系进行调驱并提高采收率提供有益启示。

The flow behavior of foam in pores affects the sweep range and displacement efficiency,and plays an important role in enhancing oil recovery.Firstly,the single capillary model is established,and the level-set method is used to study the influence factors of foam flow in a single capillary tube.The Jia Min effect,coalescence mechanism and micro selective migration mechanism of foam in porous media are analyzed.The plugging performance of different types of foam is evaluated.Secondly,a real pore medium microscopic numerical model is constructed through CT image of XB Oilfield core,and the migration characteristics of foam in it are studied.The results show that the degree of foam deformation decreases with the increase of tube diameter ratio,and the contact angle of wetting wall has no effect on the rheological properties of the foam.The critical value of liquid velocity is N_(2) when the radius of the 1.2 foam m bubble ruptures,and the pressure of the foam passes through the channel is directly proportional to the surface tension.The foam has the microscopic migration characteristics through the large channel,and the N_(2) foam has strong stability and plugging property.It is suitable for profile control and flooding in low permeability oilfield at high water cut stage,which provides beneficial enlightenment for field application of gas-liquid dispersion system for profile control and oil recovery improvement.