Study Of Flow Properties For Non-Newtonian Fluids In Porous Media Embedded With Fractal-Like Tree Networks

The fractal-like tree branching networks abound in various fields such as soils,ground water resources, mineral resources, materials science and engineering, agriculturaland sideline products, food and pharmaceuticals drying, plants, animal and internal organsof the body etc. In recent years, with the discovery and develepment of considerablefractured oil/gas fields, fractal-like tree branching networks are usually used toapproximately simulate the cracks in porous media. Therefore based on this idea, thetransport properties of a dual-porosity media comprised of fracture networks and porousmatrix become hot scientific issues. In gerenal, reservoirs may consist of randomlydistributed pores/capillaries (i.e. matrix porous media) and fracture networks whoseporosity may be different from that of matrix porous media, and they form so calleddual-porosity media. The porosity and permeability of matrix porous media depend onparticles geometries, particle size distribution and pore-interface. The porosity of matrixporous media is higher than that of fracture networks. The former can store fluid, whilethe latter can serve as preferential pathways for fluid flow. This thesis is focused on flowbehaviour for fluids in this dual-porosity media. Research results can provide certaintheoretical guidance for the engineering fields such as petroleum engineering,environmental engineering, chemical and geotechnical engineering etc.This thesis contains six chapters. The first chapter outlines the research backgroundsand the relevant theory knowledges about the porous media, the fractal-like tree networksand non-Newtonian fluids. In Chapter2, a fractal model is developed for the permeabilityof power-law fluid flow in fractal-like tree network based on straight capillary model andpower-law fluids’ generalized Darcy’s law. In Chapter3, the fractal model forpermeability of porous media embedded with a fractal-like tree network has beenpresented, which illustrates that the capillary pressure has the significant effect onpermeability. A fair agreement between the predictions from the fractal relativepermeability model and the existing experimental data is found. Chapter4presents afractal model for the starting pressure gradient for Bingham fluids in porous mediaembedded with a Y-shaped fractal-like tree network and gives the analytical expression for the starting pressure gradient of Bingham fluids in porous media embedded with aY-shaped fractal-like tree network. In Chapter5, based on the fact of real dual medium(such as oil/gas reservoirs, coal reserves, groundwater resources, mineral resources and soon)) consisting of many randomly distributed fractures and porous media with generalpore structure divided by fractures, we further investigate the flow problem for Binghamfluids in porous media embedded with randomly distributed fractal-like tree networks(dual-porosity media). The expressions for permeability and the starting pressure gradientfor Bingham fluids in porous media embedded with randomly distributed fractal-like treenetworks are obtained. Finally, a summary of the present work is given in Chapter6, andcomments are also made on the transport characteristic of the dual-porosity media basedon fractal theory.