The Study Of Capillary Pressure,Electrical Parameter And The Percentage Of Movable Fluid In The Tight Sandstone Reservoir

The microscopic pore structure characteristics of the tight sandstone reservoir is complicated,and how to interpret the feature of the capillary pressure,the resistivity and the percentage of movable fluid more accurately is always a concern of the people.The paper is focused on the feature of the microstructure of the tight sandstone reservoir,the influenced factor of resisitivity,the establishment of reservoir saturability,the relationship between the percentage of movable fluid and the pore structure complex index in the area of H and G.Therefore,the paper designs and finishes experiment and theory analysis of the casting thin sections,the scanning electron microscopy?SEM?,the semi-permeable porous-plate capillary pressure and the nuclear magnetic resonance?NMR?.The completion of the work are as follows:?1?The microscopic characteristics and mineral composition of the 12 cores are studied by casting thin sections,scanning electron microscopy?SEM?;?2?According to the result of capillary pressure and resistivity measured by the semi-permeable porous-plate,the relationship between capillary pressure and water saturation is established,further,the feature of the capillary pressure curve is analyzed;?3?On the basis of the Archie 's equation,the relationships between the formation factor and the porosity,the resistivity index and the water saturation are established.Simultaneously,combined with the result of casting thin sections and scanning electron microscopy?SEM?,the effect of rock particles,pore structure and cement on bond index and the effect of pore radius and pore connectivity on rock electivity are analyzed;?4?According to experimental Archie's parameters of two reservoir,the models of traditional and LBT saturation are established and the two models are compared by taking the area of H for example;?5?Based on the fractal theory,the power relationship between the capillary pressure and the resivitity index is established,and the relationship of power index value and permeability is analyzed;?6?Taking advantage of the experiment of the nuclear magnetic resonance?NMR?,the core curve of T₂ spectrum can be obtained.And the morphological characteristics of the saturated T₂ and the variation characteristics before and after displacement are analyzed.Combining with the result of the nuclear magnetic resonance?NMR?,two kinds of the percentage of movable fluid are put forward,which use the way of truncation and proportion.According to comparing with the way of weight,the way of proportion is more accurate.Through the experimental data analysis,there is a good power function relationship between the percentage of movable fluid and the composite index of pore structure;According to the experiment and analysis,the microstructure of the tight sandstone reservoir,the feature of the capillary pressure,the resistivity and the percentage of movable fluid are analyzed in the area of H and G,which can lay the foundation of the reservoir comprehensive assessment and exploitation.