多孔介质压敏效应对孔隙结构和渗流能力的影响研究
发布时间：2018-11-14 12:46
【摘要】：目前已有大量的宏观实验进行多孔介质中压敏效应的研究,但是压敏效应的微观机制仍较缺乏。多孔介质的孔喉结构复杂,尤其是致密砂岩等非常规储层,压敏效应会导致相应的孔喉结构发生大幅度变化,因此对孔隙级多孔介质的压敏效应进行系统的研究有重要意义。本文基于可以真实描述岩石内部结构特征的CT扫描技术,结合数字岩心和孔隙网络模型理论进行分析,获得有效应力变化与孔隙结构的变化关系;同时,建立了孔隙尺度上渗流场-应力场的流固耦合模型。在实验方面,首先,本文建立了基于CT扫描法构建数字岩心的理论与方法。CT扫描获得岩心的三维图像,经过滤波、二值分割处理得到数字岩心,提取孔隙网络模型,分析岩心的几何结构特征和拓扑结构特征,并进行流动模拟获得绝对渗透率等参数。然后,基于人造砂岩形成了一套基于CT扫描的应力敏感实验及分析方法。根据行业标准,在碳纤维岩心夹持器中进行应力敏感实验,在不同压力下对岩心进行CT扫描,构建不同应力下的数字岩心,进而提取不同应力下的孔隙网络模型,研究相应的孔隙结构特征和渗流规律。最后,将该套方法应用到实际油田的中高渗砂岩和致密砂岩,进行不同类型砂岩的应力敏感实验,并对两种砂岩的应力敏感进行对比分析。在模拟方面,基于不可压缩的N-S方程和Biot应力应变方程,构建了孔隙尺度上流固耦合数学模型,利用有限元方法进行了二维孔隙级流体流动计算,物理模型选用二维规则圆模型、二维不规则圆模型和实际SEM图像模型,得到了渗透率和孔隙度随围压以及流动压差的变化规律。通过本文研究,形成了较为完整的基于CT实验的应力敏感评价方法,对油气田开发提高采收率具有重要应用价值。
[Abstract]:At present, a large number of macroscopic experiments have been carried out to study the pressure-sensitive effect in porous media, but the microscopic mechanism of the pressure-sensitive effect is still lacking. The pore throat structure of porous media is complex, especially in unconventional reservoirs such as tight sandstone, the pressure sensitivity effect will lead to the corresponding pore throat structure change greatly, so it is of great significance to systematically study the pressure sensitivity effect of porous media. Based on the CT scanning technique which can describe the internal structure of rock, the relationship between the effective stress change and the pore structure is obtained by combining the theory of digital core and pore network model. At the same time, the fluid-solid coupling model of percolation field and stress field on pore scale is established. In the aspect of experiment, firstly, the theory and method of constructing digital core based on CT scanning method are established. Three dimensional image of core is obtained by CT scan, digital core is obtained by filtering and binary segmentation, and pore network model is extracted. The geometric and topological characteristics of the core are analyzed, and the parameters such as absolute permeability are obtained by flow simulation. Then, a set of stress-sensitivity experiments and analysis methods based on CT scanning are developed based on artificial sandstone. According to the industry standard, stress sensitivity experiments were carried out in carbon fiber core gripper, and the core was scanned by CT under different pressures to construct digital core under different stress, and then the pore network model under different stress was extracted. The pore structure characteristics and percolation law are studied. Finally, the method is applied to the medium and high permeability sandstone and tight sandstone in actual oilfield, and the stress-sensitivity experiments of different types of sandstone are carried out, and the stress sensitivity of the two types of sandstone is compared and analyzed. In the aspect of simulation, based on the incompressible N-S equation and Biot stress-strain equation, the fluid-solid coupling mathematical model on pore scale is constructed, and the two-dimensional porous fluid flow is calculated by finite element method. The physical model consists of two dimensional regular circle model, two dimensional irregular circle model and actual SEM image model. The variation of permeability and porosity with confining pressure and flow pressure difference is obtained. Through the research in this paper, a relatively complete stress-sensitive evaluation method based on CT experiment has been developed, which has important application value in oil and gas field development and improving oil and gas recovery.
【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
本文编号：2331198
[Abstract]:At present, a large number of macroscopic experiments have been carried out to study the pressure-sensitive effect in porous media, but the microscopic mechanism of the pressure-sensitive effect is still lacking. The pore throat structure of porous media is complex, especially in unconventional reservoirs such as tight sandstone, the pressure sensitivity effect will lead to the corresponding pore throat structure change greatly, so it is of great significance to systematically study the pressure sensitivity effect of porous media. Based on the CT scanning technique which can describe the internal structure of rock, the relationship between the effective stress change and the pore structure is obtained by combining the theory of digital core and pore network model. At the same time, the fluid-solid coupling model of percolation field and stress field on pore scale is established. In the aspect of experiment, firstly, the theory and method of constructing digital core based on CT scanning method are established. Three dimensional image of core is obtained by CT scan, digital core is obtained by filtering and binary segmentation, and pore network model is extracted. The geometric and topological characteristics of the core are analyzed, and the parameters such as absolute permeability are obtained by flow simulation. Then, a set of stress-sensitivity experiments and analysis methods based on CT scanning are developed based on artificial sandstone. According to the industry standard, stress sensitivity experiments were carried out in carbon fiber core gripper, and the core was scanned by CT under different pressures to construct digital core under different stress, and then the pore network model under different stress was extracted. The pore structure characteristics and percolation law are studied. Finally, the method is applied to the medium and high permeability sandstone and tight sandstone in actual oilfield, and the stress-sensitivity experiments of different types of sandstone are carried out, and the stress sensitivity of the two types of sandstone is compared and analyzed. In the aspect of simulation, based on the incompressible N-S equation and Biot stress-strain equation, the fluid-solid coupling mathematical model on pore scale is constructed, and the two-dimensional porous fluid flow is calculated by finite element method. The physical model consists of two dimensional regular circle model, two dimensional irregular circle model and actual SEM image model. The variation of permeability and porosity with confining pressure and flow pressure difference is obtained. Through the research in this paper, a relatively complete stress-sensitive evaluation method based on CT experiment has been developed, which has important application value in oil and gas field development and improving oil and gas recovery.
【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
【参考文献】
相关期刊论文 前2条
1 王晨晨;姚军;杨永飞;王鑫;;基于CT扫描法构建数字岩心的分辨率选取研究[J];科学技术与工程;2013年04期
2 戴金星;倪云燕;吴小奇;;中国致密砂岩气及在勘探开发上的重要意义[J];石油勘探与开发;2012年03期
，本文编号：2331198
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