多孔介质内颗粒流动特性研究

发布时间：2018-04-09 09:40

本文选题：多孔介质　切入点：CFD-DEM　出处：《东北石油大学》2017年硕士论文

【摘要】：岩石储油层地质构造是多孔性的,储集空间是油气赋存的场所,也是流体流动的通道,狭义上的储集岩(层)的孔隙定义为岩石中颗粒间,颗粒内和填隙物内的空隙,孔隙结构特性决定了储存流体的数量,因此,岩石储层多孔介质的研究对石油工程领域具有重大的意义。本文以石油储层多孔介质中油滴和砂粒的流动为研究对象,在微尺度内模拟多孔介质内颗粒流动特性。本文运用CFD-DEM方法对多孔介质内液相和颗粒相流动过程进行数值模拟。采用Euler方法研究液相流动,采用离散方法研究颗粒流动,并用Gidaspow曳力模型考虑液固两相相间作用,为考虑颗粒间碰撞引起的形变现象,颗粒相采用软球模型。物理模型分别建立了简单一字型多孔介质模型和分枝型多孔介质模型。研究多孔介质的孔隙率、液相粘度、液相速度、砂粒密度、以及油砂比等因素对多孔介质内流动的影响,将结果进行对比分析,得出液相和颗粒相运动规律。模拟结果表明,颗粒在多孔介质内运动过程中,液相对密度小、粒径大的油颗粒运动影响较大。多孔介质孔隙率增大时,颗粒在多孔介质内运动空间变大,颗粒停留时间增长;适当增大液相入口速度,颗粒运动速率明显增大,颗粒拟温度升高,脉动程度增加;液相粘度的增大,会阻碍颗粒的运动,影响颗粒在多孔介质中的分散程度;两种颗粒的密度差越大,多孔介质内颗粒呈现的旋转作用越强烈;不同油砂颗粒数之比对多孔介质内的颗粒运动影响明显,油砂比为1:2时的颗粒整体运移速度最快,油砂比为1:3的颗粒运移最慢,且砂颗粒容易沉积在多孔介质底部。对于分枝型多孔介质模型,颗粒在分枝通道分流效果明显。下分枝通道颗粒数量多、流动速度快,上分枝通道颗粒数量小、运动速度慢,且上分枝通道有部分砂颗粒出现回流的现象。孔隙率越大,颗粒分散程度越大,颗粒停留时间增长;液体粘度能有效改变颗粒分布情况,液体粘度增大,颗粒运动呈对称分布,粘度的增加会在一定程度上阻碍颗粒的运动,颗粒速度脉动减弱,拟温度降低;液体入口速度越大,在主通道处颗粒旋转运动越剧烈,且在下分枝通道运动的颗粒数量明显增多;不同油砂比对颗粒旋转运动影响较大,对比油砂比为1:2与油砂比为2:1两种情况的颗粒瞬时分布图,发现颗粒在主通道内会呈现出方向相反的旋转运动;对于同一模型,相邻旋转区的颗粒运动方向也相反。
[Abstract]:The geological structure of rock reservoir is porous, and the reservoir space is the place where oil and gas are stored and the passage of fluid flow. The pore of reservoir rock (reservoir) in narrow sense is defined as the void between particles in rock, in particle and in filling material.Pore structure characteristics determine the amount of fluid stored, therefore, the study of porous media in rock reservoir is of great significance in petroleum engineering field.In this paper, the flow of oil droplets and sand particles in porous media of petroleum reservoir is studied. The flow characteristics of particles in porous media are simulated in microscale.In this paper, CFD-DEM method is used to simulate the liquid phase and particle phase flow in porous media.The liquid phase flow is studied by Euler method, the particle flow is studied by discrete method, and the interaction between liquid and solid phases is considered by Gidaspow drag model. In order to consider the deformation phenomenon caused by collision between particles, the soft sphere model is used to study the particle phase.The physical model and the branched porous media model are established respectively.The effects of porosity, liquid viscosity, liquid velocity, sand density and oil-sand ratio on the flow in porous media were studied. The results were compared and analyzed.The simulation results show that the oil particles with small relative density and large particle size have great influence on the movement of oil particles in porous media.When the porosity of porous media increases, the moving space of particles in porous media becomes larger and the residence time of particles increases, and when the inlet velocity of liquid phase is properly increased, the particle moving rate increases obviously, the particle pseudo temperature increases and the pulsation degree increases.The increase of liquid viscosity will hinder the movement of particles and affect the degree of dispersion of particles in porous media, the greater the density difference between the two particles, the stronger the rotating action of particles in porous media.The effect of different ratio of oil sand particle number on particle movement in porous media is obvious. When the oil sand ratio is 1:2, the whole particle migration speed is the fastest, and the grain migration at 1:3 oil sand ratio is the slowest, and the sand particles are easy to deposit at the bottom of porous media.For the branched porous media model, the particle shunt effect in the branching channel is obvious.The number of particles in the lower branch channel is large, the velocity of flow is fast, the number of particles in the upper branching channel is small, the moving speed is slow, and some sand particles in the upper branching channel appear the phenomenon of reflux.The larger the porosity, the greater the particle dispersion, the longer the particle residence time, the more the liquid viscosity can change the particle distribution, the larger the liquid viscosity is, the more the particle motion is symmetrically distributed, and the increase of the viscosity will hinder the particle movement to a certain extent.The particle velocity pulsation is weakened and the pseudo temperature is decreased. The larger the liquid inlet velocity is, the more violent the particle rotation is at the main channel, and the number of particles moving in the lower branch channel is obviously increased, and the different oil sand ratio has a great influence on the particle rotation motion.When the oil sand ratio is 1:2 and the oil sand ratio is 2:1, it is found that the particles in the main channel show a rotating motion in opposite direction, and for the same model, the movement direction of the particles in the adjacent rotation zone is also opposite.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE311

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