Investigation On Oil-water Percolation Features In Tight Sandstone Reservoir

Tight reservoir has become the focus of world oil and gas exploration and development,because of the tight reservoir rock compact,complex pore structure,water seepage characteristics are different from the conventional reservoirs,so the study of reservoir pore throat structure dynamic characteristics and static oil-water percolation mechanism,has important significance to development of tight reservoir.First of all,the core material test,cast thin section,X ray diffraction,scanning electron microscope and mercury analysis methods to study the reservoir microstructure and static characteristics.The pressure-controlled mercury injection and rate-controlled mercury injection were using to study the pore,throat radius and the fractal dimension of variation in the development process in the long period.Secondly,different properties,displacement pressure and effective stress of oil-water two-phase flow experiment were carried out.Meanwhile,different injection rate,cumulative liquid production,oil displacement efficiency,variation of water content were studied,and analysis physical properties,displacement pressure and confining pressure on the relative permeability curves.Then,combined with high pressure and centrifugal displacement experiment method to study the irreducible water saturation,analyzes the core properties,pore structure parameters and irreducible water saturation off Based on the fractal theory of porous media,the theoretical calculation model of relative permeability of dense core is established.The experimental data are used to verify the model,and the variation law of irreducible water saturation,residual oil saturation and relative permeability with displacement pressure under different pore parameters is analyzed.