渗流边界层对低渗透油藏微观流动规律影响研究

发布时间：2019-05-17 02:45

【摘要】：低渗油藏的开发是目前增储上产的重要阵地之一,目前还是基于以达西渗流方程为基础的宏观渗流理论,为了更精确研究边界层等因素对渗流的影响,利用数字岩心技术进行边界层对低渗透砂岩介质的流动研究具有明显优势。国内外学者通过多种方法建立了可以准确描述岩石孔隙结构的数字岩心,其中,以CT扫描技术为基础建立的数字岩心最接近岩石真实结构。本文首先利用MicroX CT-400型CT对岩心进行扫描实验,构建数字岩心,优化数字岩心结构,删除数字岩心中的孤立孔隙。基于所建立的数字岩心,利用孔隙空间居中轴线法提取孔隙网络模型,进行岩心结构特征分析,获得孔隙网络模型的几何特征参数(孔喉半径、形状因子、迂曲度)以及拓扑结构特征参数(配位数、网络连通性函数)。对孔隙网络模型进行流动模拟,得到了油驱水过程中,每一步孔隙和喉道的含油饱和度分布。然后,分析了原油粘度在不同环境下的计算式,基于所构建的数字岩心和孔隙网络模型,分析边界层主要性质对渗流的影响,利用iso2mesh软件对低渗透砂岩岩心进行几何重构,基于有限元数值分析算法,利用COMSOL Multiphysics软件对重构后的岩心进行微流动数值模拟,研究孔隙空间速度场、压力场以及流体流动状态的分布。最后,分析了压力梯度对边界层厚度的影响,并对边界层的厚度和粘度进行了无量纲处理,定量分析了边界层对低渗透砂岩微观流动的影响,边界层粘度对低渗透砂岩微流动的影响以及边界层厚度对低渗透砂岩微流动的影响。通过本文研究,形成了较为完整的基于数字岩心的边界层对低渗透砂岩介质的流动模拟研究方法,对低渗透油田的开发具有重要的应用价值和一定的学术意义。
[Abstract]:The development of low permeability reservoir is one of the important positions to increase reservoir production at present. At present, it is still based on the macro seepage theory based on Darcy seepage equation, in order to study the influence of boundary layer and other factors on seepage more accurately. Using digital core technology to study the flow of low permeability sandstone medium in boundary layer has obvious advantages. Scholars at home and abroad have established digital cores which can accurately describe the pore structure of rocks by various methods, among which the digital cores based on CT scanning technology are closest to the real structure of rocks. In this paper, MicroX CT- 400 CT is used to scan the core, to construct the digital core, to optimize the structure of the digital core and to remove the isolated pores in the digital core. Based on the established digital core, the pore network model is extracted by the pore space center axis method, and the core structure characteristics are analyzed, and the geometric characteristic parameters (pore throat radius, shape factor) of the pore network model are obtained. Roundness) and topological characteristic parameters (coordination bits, network connectivity functions). The flow simulation of pore network model is carried out, and the oil saturation distribution of pores and throat in each step of oil flooding process is obtained. Then, the formulas of crude oil viscosity in different environments are analyzed. Based on the digital core and pore network model, the influence of the main properties of boundary layer on seepage is analyzed, and the geometric reconstruction of low permeability sandstone core is carried out by using iso2mesh software. Based on the finite element numerical analysis algorithm, the micro-flow numerical simulation of the reconstructed core is carried out by using COMSOL Multiphysics software, and the distribution of pore space velocity field, pressure field and fluid flow state is studied. Finally, the influence of pressure gradient on the thickness of boundary layer is analyzed, and the thickness and viscosity of boundary layer are treated without dimension, and the influence of boundary layer on the microscopic flow of low permeability sandstone is quantitatively analyzed. The effect of boundary layer viscosity on the microflow of low permeability sandstone and the effect of boundary layer thickness on the microflow of low permeability sandstone. Through the study of this paper, a more complete flow simulation method of boundary layer based on digital core for low permeability sandstone medium has been formed, which has important application value and certain academic significance for the development of low permeability oil field.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE312

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