Fractal Study On Roughness And Seepage Characteristics Of Fractured Porous Media

Porous media is a general term for a substance composed of solid skeleton and tiny pores.There are many types of porous media.According to their internal pore structure and shape,they can be divided into porous porous media,fractured porous media,and multiple media.The morphology of porous media in nature does not exist alone,and it is mostly a dual media composed of a porous matrix and a fracture network.A large number of researchers only study the seepage characteristics of its simp le form,assuming that the pores and cracks are evenly distributed and the inner surface is smooth.However,the internal structure of the fissured dual medium is very complicated,the pores and cracks are randomly and disorderly distributed,and the inner surface of the channel is rough.Therefore,based on the fractal theory and the seepage characteristics of multiple media,the fractal model of channel surface roughness and random distribution of channel is established,and the fractal dimension,tortuosity,roughness,capillary shape factor,gas slip factor,crack are studied The effect of opening degree,randomness of channel and heterogeneity on the seepage of dual media with roughness.The research in this paper is one of the hot topics in the cross-category of geophysics,theoretical physics and complexity science.In addition,in mechanical seals,the leakage of fluid through non-metallic gaskets can also be described with a dual-media seepage model.The specific work of this article is as follows:Based on porous media,a triangular pyramid geometric model of fractal surface roughness element was established;Then the fractal models of the relative roughness of the surface of the cracked flat plate and the cylindrical capillary are respectively proposed.The resulting model does not contain any constants,and each parameter in the model has a specific physical meaning;Based on the relative roughness fractal model,the Reynolds number and Fanning friction factor are deduced to verify the accuracy of t he model in this paper;Finally,the effect of surface roughness along with the geometric parameters of rough elements and fractal dimension on relative roughness is discussed.In addition,numerical simulation is also an effective way to study porous media seepage.Based on the Monte Carlo simulation method,this paper proposes a new algorithm to simulate the generation process of rough surface.The study found that the fractal dimension mainly affects the distribution of surface roughness element density and height frequency value distribution,while the characteristic height mainly affects the maximum fluctuation amplitude value of surface roughness element height.The fractal dimension of the fractured dual media,the relative roughness and morphology of the microchannel surface,and related structural parameters have important effects on the seepage characteristics.In this paper,the capillary shape factor is proposed,and the fractal models of the rough volume flow of porous matrix and fracture medium are obtained respectively,and the influence of each important parameter on the fractal permeability is analyzed.It is found that the relative roughness,fractal dimension and shape have a significant influence on the permeability.In addition,in the fra ctured double medium,the fracture medium is the main transmission system.Gas phase seepage is also an important part of studying the seepage characteristics of porous media.This paper considers the effects of roughness and capillary shape,and obtains a rough fractal permeability model of saturated gas in fractured dual media,and verifies that the model is reasonable.The expressions of gas slip factors are obtained,which are functions of fractal dimension and structural parameters of porous media;Fin ally,the effects of dual media structure parameters and fractal dimensions on seepage characteristics and slip factors are analyzed.