Fractal Analysis Of Dimensionless Capillary Pressure Function And Effects Of Pressure On The Capillary Fluid Flow

Porous media widely exists in nature and production as well as in daily life.Therefore, carefully studying the structures of porous media and fluid characteristics willhave the great significance on understanding the nature and improving industrialproductions. This thesis mainly focuses on studying three problems in the process of oilextraction based on fluid mechanics and fractal geometry theory for porous media. First,we study the mechanisms that the dimensionless capillary pressure function can be used todivide the types of different pore structures; Secondly, we study the flow characteristics inthe exploitation of petroleum with water injection; Thirdly, we study the analyticalexpression of the effective permeability by considering capillary pressure based on thefractal geometry theory for porous media.The dimensionless capillary pressure function J (SW)was used to eliminate thecapillary pressure difference between different strata and to describe similar lithologicreservoirs. Based on the existing function J (SW)and the fractal geometry theory forporous media, a fractal model for describing the pore structure of the lithology ispresented. The proposed fractal expression for the J (SW)function reveals that when themicrostructural parameters (fractal dimension for pore area, the fractal dimension fortortuosity, and the ratio of the maximum pore diameter to the minimum pore diameter) areequal or close, respectively, for porous samples (with different permeabilities, porosities,interfacial tensions and wetting angles), the values of the J (SW)function versus saturationcoincide each other for wetting phase. The proposed fractal expression for the relativepermeability of wetting phase may have the potential in exploitation of oil fields. Besides,a new dimensionless function G (SW)is also proposed to describe the relationship amongthe structural parameters of strata and saturation as well as capillary pressure.In exploitation of petroleum with water injection, one need to clearly study the fluidcharacteristics to better explain various phenomena and develop appropriate solutions toget oil more effectively. From the theoretical level, this thesis analyzes the process of water oil displacement to more clearly show the displacement process of internal changeprocess such as fingering phenomenon, oil and water mixing zone and nonlinear flowcharacteristics etc.Study of permeability for power law fluid in porous media is of great significance,and this thesis derives the fractal analytical expression for the effective permeability ofpower-law fluid in porous media based on the fractal geometry theory for porous media.