考虑液—固界面作用的微可压缩流体的渗流理论研究

发布时间：2018-01-14 07:02

本文关键词：考虑液—固界面作用的微可压缩流体的渗流理论研究　出处：《北京科技大学》2015年博士论文　论文类型：学位论文

【摘要】：低渗透多孔介质中流体的流动具有非线性渗流特征,对其流动规律的描述通常是在渗流规律实验和参数拟合的基础上,建立非达西渗流数学模型,其结果未能揭示非线性渗流的机理和物理本质,一直缺乏从基础理论出发的分析结果。本文从流体力学角度分析其根本原因,通过实验分析、理论模型和数值模拟相结合的方法,建立了考虑液固界面作用的微可压缩流体的渗流理论模型,为研究多孔介质的非线性渗流规律奠定了理论基础,提供了新的研究方法。论文首先从微圆管流动实验入手,研究流体在微尺度下的非线性流动。通过对微流动非线性的影响因素分析,发现非线性流动特征明显,出现了启动压力梯度现象。从液固界面作用的角度出发,改变了微圆管壁面的亲疏水性,发现流体在相同管径下的微圆管中流速得以提高,流动阻力得以降低,体现了液固界面作用力对流体在微圆管内流动的重要影响。综合应用流体力学、渗流力学、现代数学、现代非线性力学等理论分析方法,考虑长程固液静电力和范德华力及流体微可压缩性的影响,建立了流体非线性运动方程组,引入涡函数和流函数,利用正则摄动法求得速度和压力分布的近似解析解。计算结果表明考虑界面力和微可压缩性条件下流体非线性特征和微尺度效应明显,且与微管实验规律一致。从流体的微可压缩性和液固界面作用力的角度揭示了产生非线性流动的原因。以微管单相流动数学模型为基础,建立了考虑液固界面作用及流体微可压缩性的两相非稳态流动数学模型；利用微管两相流动数学模型,建立了反映多孔介质流动特征的毛管束模型,对比分析了流体的微可压缩性和液固界面作用力对进出口端定压、进口定流量出口定压力两种情况下水驱油规律的影响。采用水驱油动态网络模型,模拟了考虑液固界面作用的微可压缩流体在网络模型中的流动,分析了流体的微可压缩性、液固界面作用力、平均喉道尺度和驱动压力对剩余油分布类型及比例的影响。结果表明,微可压缩性和液固界面作用对剩余油比例影响较大,以簇状剩余油为主；平均喉道半径越小,剩余油比例越高,以簇状剩余油为主；当喉道半径变大,压力梯度变大,剩余油较少时,膜状剩余油最难驱替。结果显示簇状剩余油和膜状剩余油的形成受液固界面力的影响最大,为挖潜剩余油提供了理论依据。
[Abstract]:The flow of fluid in low permeability porous media has nonlinear seepage characteristics. The description of the flow law is usually based on the experiment of seepage law and parameter fitting, the mathematical model of non-Darcy seepage is established. The results fail to reveal the mechanism and physical nature of nonlinear seepage, and there is a lack of analysis results based on the basic theory. This paper analyzes the fundamental causes from the point of view of fluid mechanics, and analyzes them through experiments. By combining theoretical model with numerical simulation, a theoretical model of micro-compressible fluid flow considering liquid-solid interface is established, which lays a theoretical foundation for the study of nonlinear seepage law of porous media. A new research method is provided. In this paper, the nonlinear flow of microtube is studied by the experiment of microtube flow. Through the analysis of the influence factors of the nonlinear of micro-flow, it is found that the characteristics of nonlinear flow are obvious. From the point of view of liquid-solid interface, the hydrophobicity of the wall of the microtube was changed. It was found that the flow velocity of the fluid in the microtube with the same diameter was increased and the flow resistance was reduced. The effect of liquid-solid interface force on the flow of fluid in a microtube is demonstrated. The effects of long range solid-liquid hydrostatic power, van der Waals force and micro-compressibility of fluid are considered by using the theoretical analysis methods of fluid mechanics, seepage mechanics, modern mathematics and modern nonlinear mechanics. The equations of nonlinear motion of fluid are established, and vortex function and current function are introduced. The approximate analytical solution of velocity and pressure distribution is obtained by using the regular perturbation method. The results show that the nonlinear characteristics and micro-scale effects of the fluid are obvious when the interface force and the micro-compressibility are taken into account. In accordance with the experimental rule of microtubules, the causes of nonlinear flow are revealed from the point of view of fluid microcompressibility and liquid-solid interface forces. Based on the mathematical model of single-phase flow in microtubules, a mathematical model of two-phase unsteady flow considering the interaction of liquid-solid interface and the micro-compressibility of fluid is established. A capillary bundle model reflecting the flow characteristics of porous media was established by using the mathematical model of microtubule two-phase flow. The micro-compressibility of the fluid and the pressure of the liquid-solid interface on the inlet and outlet end were compared and analyzed. The influence of the water displacement law in the two situations of constant flow inlet and outlet constant pressure. The flow of micro-compressible fluid considering liquid-solid interface in the network model is simulated by using water drive oil dynamic network model. The micro-compressibility of fluid and the interaction force of liquid-solid interface are analyzed. The effects of average throat size and driving pressure on the distribution and proportion of residual oil show that micro-compressibility and liquid-solid interface have great influence on the remaining oil ratio, mainly cluster residual oil. The smaller the average throat radius, the higher the remaining oil ratio, mainly cluster residual oil. When the throat radius becomes larger, the pressure gradient becomes larger, and the remaining oil is less, the membrane residual oil is the most difficult to displace. The results show that the formation of the cluster residual oil and the film residual oil is most affected by the liquid-solid interface force. It provides a theoretical basis for tapping the remaining oil.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE312

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