弱胶结砂岩油藏出砂细观力学机理研究

发布时间：2018-03-16 21:41

本文选题：弱胶结砂岩　切入点：出砂　出处：《武汉轻工大学》2015年硕士论文　论文类型：学位论文

【摘要】：弱胶结砂岩是我国油藏的主力储油层,开采过程中普遍存在出砂现象,大量出砂常常会造成砂埋油层或井筒砂堵等工程灾害;但另一方面,适量的出砂可以增强储层的渗透性,进而提高采出率。因此,深入研究弱胶结砂岩油藏的出砂机理,合理的控制出砂既有利于石油开采过程中的灾害防治,也有利于提高采收率。本文以弱胶结砂岩为研究对象,首先采用图像处理的方法研究了其细观孔隙结构特征,然后采用理论和实验相结合的方法建立其统计损伤本构模型,最后采用数值模拟的方法研究了砂岩损伤导致出砂的动态过程。主要研究工作如下:(1)选取典型弱胶结砂岩试样进行CT扫描实验,获取其细观结构图像;基于MATLAB图像处理工具箱对细观结构图像进行处理,分离出砂岩的孔隙结构;对分离出的孔隙结构进行分析,获取其统计学参数;进而基于Monte-Carlo随机模拟技术研究了孔隙结构的重建方法。(2)考虑弱胶结砂岩内胶结物和基质颗粒在力学性质上的非均质性,假定砂岩内微元的强度服从Weibull分布,基于Drucker-Prager模型建立了弱胶结砂岩的统计损伤本构模型,推导了模型的表达式和Weibull分布参数m和F0的计算方法;结合砂岩单轴实验,验证了理论全程应力-应变曲线和实验曲线的一致性,检验了所建立的统计损伤本构模型的有效性。(3)基于统计砂岩细观模型建模方法,生成具有不同孔隙率的砂岩模型,结合ABAQUS稳态渗流功能,分析孔隙率对砂岩渗透系数的影响规律。(4)基于通用有限元软件ABAQUS的材料本构模型接口UMAT,编程实现了所建立的损伤本构模型;在ABAQUS平台上,基于所建的统计本构模型,结合所建立的损伤本构模型,采用数值模拟方法研究了砂岩在单轴受压作用下砂岩的微裂纹起裂及其扩展的动态过程。
[Abstract]:Weak cemented sandstone is the main reservoir in our country. Sand production is common in the process of production. A large amount of sand production often results in engineering disasters such as sand buried oil layer or wellbore sand plugging, but on the other hand, proper sand production can enhance the permeability of reservoir. Therefore, further study on sand production mechanism of weakly cemented sandstone reservoir and reasonable control of sand production are not only beneficial to disaster prevention during oil production, but also to oil recovery. This paper takes weak cemented sandstone as the research object. Firstly, the characteristics of meso-pore structure were studied by image processing, and then the statistical damage constitutive model was established by combining theory with experiment. Finally, the dynamic process of sand production caused by sandstone damage is studied by numerical simulation. The main research work is as follows: 1) the typical samples of weakly cemented sandstone are selected for CT scanning experiment, and the meso-structure images are obtained. Based on MATLAB image processing toolbox, the pore structure of sandstone is separated, the pore structure is analyzed and its statistical parameters are obtained. Furthermore, based on the Monte-Carlo stochastic simulation technique, the reconstruction method of pore structure is studied. (2) considering the heterogeneity of mechanical properties of cemented and matrix particles in weakly cemented sandstone, it is assumed that the strength of microelements in sandstone is distributed from Weibull. Based on the Drucker-Prager model, the statistical damage constitutive model of weakly cemented sandstone is established, the expression of the model and the calculation method of Weibull distribution parameters m and F0 are derived. The consistency of the stress-strain curve and the experimental curve is verified. The validity of the established statistical damage constitutive model is tested. Based on the statistical sandstone meso-model modeling method, the sandstone model with different porosity is generated. Combined with the steady flow function of ABAQUS, the influence of porosity on sandstone permeability is analyzed. (4) based on the interface of material constitutive model of general finite element software ABAQUS, the damage constitutive model is programmed and realized on ABAQUS platform. Based on the statistical constitutive model and the damage constitutive model, the dynamic process of micro-crack initiation and propagation of sandstone under uniaxial compression is studied by numerical simulation.
【学位授予单位】：武汉轻工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE311

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