3D numerical reconstruction of well-connected porous structure of rock using fractal algorithms

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This article reports recent developments and advances in the simulation of the CO 2 -formation fluid displacement behaviour at the pore scale of subsurface porous media. Roughly, there are three effective visualization approaches to detect and observe the CO 2 -formation fluid displacement mechanism at the micro-scale, namely, magnetic resonance imaging, X-ray computed tomography and fabricated micromodels, but they are not capable of investigating the displacement process at the nano-scale. Though a lab-on-chip approach for the direct visualization of the fluid flow behaviour in nanoscale channels has been developed using an advanced epi-fluorescence microscopy method combined with a nanofluidic chip, it is still a qualitative analysis method. The lattice Boltzmann method (LBM) can simulate the CO 2 displacement processes in a two-dimensional or three-dimensional (3D) pore structure, but until now, the CO 2 displacement mechanisms had not been thoroughly investigated and the 3D pore structure of real rock had not been directly taken into account in the simulation of the CO 2 displacement process. The status of research on the applications of CO 2 displacement to enhance shale gas recovery is also analyzed in this paper. The coupling of molecular dynamics and LBM in tandem is proposed to simulate the CO 2 -shale gas displacement process based on the 3D digital model of shale obtained from focused ion beams and scanning electron microscopy.

Section: Fabricated Micromodelsmentioning

confidence: 99%

Simulation and visualization of the displacement between CO2 and formation fluids at pore-scale levels and its application to the recovery of shale gas

Hou

Gao

et al. 2016

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“…The concrete specimens were constructed by mixing cement and Visual representation and characterization of three-dimensional hydrofracturing cracks… 285 aedelforsite gravel, in which the amount and grading of the gravel was probed by detecting the gravel distribution of natural glutenite cores drilled from the Shengli SINOPEC oil field at a depth of 4000 m. The reason for using the inner structure of cement specimens for reference is that the matrix and gravels can be easily distinguished in the artificial specimens. In order to construct the 3D numerical model, a multi-thresholding segmentation method and a self-developed computer program (Ju et al 2013(Ju et al , 2014b were used to enhance and digitize the original images into binary pixels of gray and white that represented matrix and gravel, respectively. Furthermore, square images were cut into circles in order to construct cylindroid models.…”

Section: Ct Identification Of Heterogeneous Structurementioning

confidence: 99%

Visual representation and characterization of three-dimensional hydrofracturing cracks within heterogeneous rock through 3D printing and transparent models

Liu

Ranjith

et al. 2016

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The heterogeneity of unconventional reservoir rock tremendously affects its hydrofracturing behavior. A visual representation and accurate characterization of the three-dimensional (3D) growth and distribution of hydrofracturing cracks within heterogeneous rocks is of particular use to the design and implementation of hydrofracturing stimulation of unconventional reservoirs. However, because of the difficulties involved in visually representing and quantitatively characterizing a 3D hydrofracturing crack-network, this issue remains a challenge. In this paper, a novel method is proposed for physically visualizing and quantitatively characterizing the 3D hydrofracturing crack-network distributed through a heterogeneous structure based on a natural glutenite sample. This method incorporates X-ray microfocus computed tomography (lCT), 3D printing models and hydrofracturing triaxial tests to represent visually the heterogeneous structure, and the 3D crack growth and distribution within a transparent rock model during hydrofracturing. The coupled effects of material heterogeneity and confining geostress on the 3D crack initiation and propagation were analyzed. The results indicate that the breakdown pressure of a heterogeneous rock model is significantly affected by material heterogeneity and confining geostress. The measured breakdown pressures of heterogeneous models are apparently different from those predicted by traditional theories. This study helps to elucidate the quantitative visualization and characterization of the mechanism and influencing factors that determine the hydrofracturing crack initiation and propagation in heterogeneous reservoir rocks.

“…The meshed model information of the reference model and the two reconstructed Macroscopic behavior of rocks 335 models were subsequently converted to the format that can be used in the SciFEA, i.e. the self-developed nonlinear software (Ju et al 2014). …”

Section: Finite Element Model Constructionmentioning

confidence: 99%

“…A fractal descriptor which characterizes the complexity of pore morphology is introduced into the reconstruction procedure and act as one of the statistical information control function. For more information about the reconstruction procedure, please refer to the paper 3D Numerical Reconstruction of Well Connected Porous Structure of Rock Using Fractal Algorithms (Ju et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Influence of pore structures on the mechanical behavior of low-permeability sandstones: numerical reconstruction and analysis

Zheng

Zhao

2014

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The research of rock properties based on its inherent microscopic to mesoscopic porous structure has drawn great attention for its potential in predicting the macroscopic behavior of rocks. An accurate reconstruction of the threedimensional porous structure is a premise for the related studies of hydraulic and mechanical properties of rocks, such as the transport properties and mechanical responses under pressures. In this paper, we present a computer procedure for reconstructing the 3D porous structure of low-permeability sandstone. Two large-size 3D models are reconstructed based on the information of a reference model which is established from computed tomography (CT) images. A self-developed finite element method is applied to analyze the nonlinear mechanical behavior of the sandstone based on its reconstructed model and to compare the results with those based on the reference model. The good consistency of the obtained mechanical responses indicates the potential of using reconstruction models to predict the influences of porous structure on the mechanical properties of low-permeability sandstone.