| Although percolation theory was made to the present for only 50 years, many important research results have been made in theoretical and applied research on percolation theory, and it is widely used in many fields, became a major research methods and research tools. It is well known that pore and fracture offer the only space for flow of liquid in pore and fracture double-medium, this space's connectivity decide the permeability of coal and rock from the micro-structure, the percolation theory has offered a new thinking for our research, the percolation theory is suitable for studying the random and disordered medium, The coal and rock is just kind of medium, so there is a natural connection between them, but up to now, the percolation model that is suited to study the pore and fracture double-medium has not been set up, so the thesis has expanded the application fields of percolation theory, there is important practical value.The thesis set up the 3D porous model,3D fracture model and 3D pore and fracture model, based on VC++6.0 and OpenGL, developed the software used in the simulation of percolation, studied on the law of percolation and the character of the largest cluster, studied on the distribution state and connectivity of pore cluster in coal and several kinds of sandstone, have developed the application software used for setting up "three-dimension data rock samples", With percolation theory and its research methods to research the three-dimensional data rock samples. based on the value of 3D percolation probability, proposed the classification method of the coal micro-structure connectivity. The following is main research contents and research results:1. Start from percolation theory, the recursive matrix of 3D site percolation model has been set up by the relationship between graph and matrix, the analytical result and percolation curve of 2×2×2 model have been gotten, calculated the threshold numerical value and the iterative formula of 3D site percolation model by the method of the renormalization:pn=pn-18+8pn-17(1-pn-1)+28pn-16(1-pn-1)2+56pn-15(1-pn-1)3+55pn-14(1-pn-1)4+24pn-13(1-pn-1)5+4pn-12(1-pn-1)62. Used the high accuracy micro- CT machine studied on the distribution state and connectivity of pore cluster in coal and several kinds of sandstone, and the relationship between the scale and the porosity, it obey the power relation, On the basis of scanning resulting micro-CT picture, set up "three-dimension data rock samples", reproduction of the real 3D distribution of pore and fracture in coal and rock, Using VC++6.0 developed the simulation program of three-dimensional porous media, simulated the fractal character and distribution of the largest cluster, Obtain the fractal dimension of percolation cluster under the two-dimensional situation and three-dimensional situation: D3 = D2 +13. Introduced the fractal law of fractures distribution, and adding fractures into 3D lattice site percolation model, set up the model of 2D and 3D pore and fracture double-medium, Using VC++6.0 developed the simulation program of 3D percolation, simulated and calculated a large number of percolation probability, obtain the critical function of percolation under the two-dimensional situation and three-dimensional situation:f(n,N0,D) =ncp-n-N0Exp(4.468(D-d))here: D is the fractal dimension of fractures, d is the dimension of the percolation model, when d=2, ncp =0.59275, d=3, ncp=0.3116; n is porosity, N0 is the initial value of fracture quantity distributionWhen f(n,N0,D)>=0, there is not percolation cluster inside the double medium, it can not penetrate. On the contrary, when f(n,N0,D)<0, it appear percolation cluster inside the double medium, and the medium can penetrate.4. Using Monte Carlo method generated 3D network system of fractures, and adding the fractures into 3D percolation model of porous medium, set up the model of 3D pore and fracture double-medium based on Monte Carlo method, according to this model, calculated the percolation probability of 3D double medium as the porosity and the quantity of fractures have different value, studied on the influence of the fractures on the percolation probability of double medium. Introduce the concept of fractures volume density, compared to the percolation law of fractal factures and the percolation law of Monte Carlo fractures, discover: there is similarity and difference between the two kinds of models, the similarity is that the figure of percolation curve is similar, and the difference is that the critical value of fracture volume density is 0.3, the value is a constant, and do not change with the initial value of fracture quantity distribution, On the other side, when the even value of fracture's radius is increasing, the critical value of fracture's volume density is decreasing.5.Disscused the role of different aperture pore and fracture in transportation course of coalbed methane, in different aperture pores, The gas has different flow ways, and the way decide the velocity of flow of the gas, in the large pores and fractures, the velocity of flow of the gas is speedy, so connectivity and quantity of the large pores and fracture decide the permeability of coal and rock from the micro-structure, calculated the percolation probability of coal which have different rotten grad, and analyses the connectivity of pores and fractures quantificationally, And based on the percolation probability, proposed the classification method of the coal micro-structure connectivity. The classification method can describe the connectivity of pores and fractures quantificationally, thus it can be applied to estimate the gas drainage in coalbed, The method has important practical value.
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