A statistical model for porous structure of rocks

Ju, Yang; Yang, Yongming; Song, Zhenduo; Xu, Wei

doi:10.1007/s11431-008-0111-z

Cited by 43 publications

(37 citation statements)

References 27 publications

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“…Hence steady progress has been made in two areas, specifically the mechanism of evolving defects or cracks and the elucidation of damage constitutive relationships. Ju et al [20][21][22] investigated the geometric features and distribution properties of pores in rocks by means of CT scanning tests of sandstone and foam concrete, and then constructed a statistical model of rock pore structure that was used in numerical simulation by finite-element software. The results indicated the important role of CT technology for researching microscopic damage of rock materials.…”

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Computation of fractal dimension of rock pores based on gray CT images

et al. 2011

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The characterization of pore structure in rocks is relevant in determining their various mechanical behaviors. Digital image processing methods integrated with fractal theory were applied to analyze images of rock slices obtained from industry CT, elucidating the characteristics of rock pore structure and the relationship between porosity and fractal dimensions. The gray values of pixels in CT images of rocks provide comprehensive results with respect to the attenuation coefficients of various materials in corresponding rock elements, and these values also reflect the effect of rock porosity at various scales. A segmentation threshold can be determined by inverse analysis based on the pore ratios that are measured experimentally, and subsequently binary images of rock pores can be obtained to study their topological structures. The fractal dimension of rock pore structure increases with an increase in rock pore ratio, and fractal dimensions might differ even if pore ratios are the same. The more complex the structure of a rock, the larger the fractal dimension becomes. The experimental studies have validated that fractal dimension calculated directly from gray CT images of rocks can give an effective complementary parameter to use alongside pore ratios and they can suitably represent the fractal characteristics of rock pores. As complex geological materials, rocks have discontinuous, non-homogeneous, multi-phase composite structures. Many irregular pores occur at different scales that affect the physical, mechanical and chemical properties of rock materials; such as strength, elastic modulus, permeability, conductivity, wave velocity, particle surface adsorption, and the capacity of a rock reservoir. A significant problem in petroleum exploration, mining, metallurgy, civil and hydraulic engineering is how to understand and quantitatively characterize the evolution of pore structures in rock materials. Thus far, more than 30 kinds of parameters have been proposed to describe rock pore structures [1,2]; these include density or volume fraction of pores (poreratio), pore size and its distribution, and specific surface area. These parameters mainly characterize the average pore structure from a macroscopic view. Pore ratio is the most readily available basic parameter, the effect of which is far greater than all the other factors; therefore, studies related to pore ratios are the most common. Determining pore ratios involves use of microscopic image analysis, weighing method, immersion method and mercury, which have been discussed in detail elsewhere [1,3]. Because pore structures in rocks are very complex [4][5][6], advanced measurement techniques have gradually been introduced to describe pore structures at different scales [7]. Pore morphology and microstructure in rocks can be observed and analyzed over different magnifications using optical or scanning electron microscopy. X-ray fluoroscopy methods also have been adopted to observe internal rock structures. A more effective method is Computerized Tomography (CT...

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Computation of fractal dimension of rock pores based on gray CT images

et al. 2011

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“…However, according to a large number of experiment results, due to the complex micro pore structure characteristics and the limitation of experiment environment, the conventional experiment cannot describe the real nonlinear seepage of actual reservoir accurately [8,9]. Therefore, in order to reproduce the fluid flow and displacement process in the micro pore structure, scholars have carried out the digital core reconstruction and micro model seepage experiment based on CT scanning [10][11][12][13]. The micro slice model which is used in micro seepage experiment based on real core can keep the complete pore structure and morphological character.…”

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confidence: 99%

A Pore Scale Flow Simulation of Reconstructed Model Based on the Micro Seepage Experiment

2017

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Researches on microscopic seepage mechanism and fine description of reservoir pore structure play an important role in effective development of low and ultralow permeability reservoir. The typical micro pore structure model was established by two ways of the conventional model reconstruction method and the built-in graphics function method of Comsol5 in this paper. A pore scale flow simulation was conducted on the reconstructed model established by two different ways using creeping flow interface and Brinkman equation interface, respectively. The results showed that the simulation of the two models agreed well in the distribution of velocity, pressure, Reynolds number, and so on. And it verified the feasibility of the direct reconstruction method from graphic file to geometric model, which provided a new way for diversifying the numerical study of micro seepage mechanism.

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“…The discrete element model is used to study the relationship between stress and strain, acoustic emission characteristics, strain localization, and shear reinforcement [12]. The three-dimensional statistical model of rock pore structure is constructed, and the influence of the pore on the stress distribution, the failure mode, and the fracture connectivity of rock are analyzed [13]. The threedimensional pore model is established and the influence of pore structure parameters on the mechanical properties of porous sandstone is discussed [14].…”

Section: Introductionmentioning

confidence: 99%

Reconstruction of 3D Micro Pore Structure of Coal and Simulation of Its Mechanical Properties

Guang-zhe

Zheng

2017

Advances in Materials Science and Engineering

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This article takes the low permeability coal seam in the coalfield of South Judger Basin in Xinjiang, as a research object. The pore structure characteristics of coal rock mass in low permeability coal seam were analyzed quantitatively using scanning electron microscopy (SEM) through the methods of statistics and digital image analysis. Based on the pore structure parameters and the distribution function of the coal rock mass, a three-dimensional porous cylinder model with different porosity was reconstructed by FLAC3D. The numerical simulation study of reconstructed pore model shows that (1) the porosity and the compressive strength have obvious nonlinear relation and satisfy the negative exponential relation; (2) the porosity significantly affects the stress distribution; with the increase of micro porosity, the stress distribution becomes nonuniform; (3) the compressive failures of different models are mainly shear failures, and the shape of fracture section is related to porosity; (4) the variation of seepage coefficient of the pore reconstruction model is consistent with the development of micro cracks. The micro mechanism of the deformation and failure of coal and the interaction of multiphase flow with porosity are revealed, which provides a theoretical reference for the clean development of the low permeability coal seam.

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A statistical model for porous structure of rocks

Cited by 43 publications

References 27 publications

Computation of fractal dimension of rock pores based on gray CT images

Computation of fractal dimension of rock pores based on gray CT images

A Pore Scale Flow Simulation of Reconstructed Model Based on the Micro Seepage Experiment

Reconstruction of 3D Micro Pore Structure of Coal and Simulation of Its Mechanical Properties

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