Three-dimensional Reconstruction Of Core Based On CT Images And Simulation Of Microscopic Transport Process

In recent years,a large number of anomalous transport phenomena have been discovered in engineering practice and laboratories,and have gradually become a research hotspot.The CTRW theory is widely used in the study of anomalous transport because of its simple application and high accuracy.However,the CTRW theory is essentially a statistical model of probability and belongs to the phenomenological theory.It lacks a clear physical mechanism.Due to the development of digital core technology and the continuous improvement of the pore extraction algorithm in the past decade,it has become possible to quantitatively describe the core pore space,providing the basis for further discussion on the relationship between CTRW theoretical parameters and pore characteristics.The specific work is as follows:In chapter 2,median filter processing for CT image of the core and the pores in the image are identified.Calculate the change of porosity and axial and radial porosity of 4 core samples and statistical variables such as Hurst index.In chapter 3,the maximum sphere method is used to extract the core pore space equivalently into a three-dimensional complex pore network,and the radius,length,and degree distributions are calculated.The Poistry's law and Laplacian matrix are used to calculate the flow field on the maximum connected subgraph of the network.In chapter 4,we use the random walk model to simulate the convection and diffusion of particles on the network,and calculate the exponential power of the particles' mean square displacement over time.A probabilistic precision matrix model is proposed,and the matrix form and the solution method to describe the flow of probabilistic flows over the network are given.Using this method in the core sample network,it was found that the particle transport on the network belongs to type II transport.The probabilistic precision matrix method considers the pore network space characteristics(structure),fluid boundary conditions,and particle initial conditions.It can calculate the exact weight of each side of the network to contribute to the transport.The bridge between the CTRW theory and the microscopic transportation process was erected,which deepened the understanding of the CTRW theory and was of great significance to related theoretical research and engineering practice.