关键词: 致密砂岩, 孔隙结构, 多重分形特征, 分形区间, 分形维数, 定量表征

Abstract: The pore structure of tight sandstone formation is very complicated, which has significant effects on the percolation of oil and gas. So, elaborate characterization is needed. The fractal geometry theory has provided an effective way for the quantitative characterization of pore structure. Based on the mercury intrusion data of the tight sandstone samples collected from FY formation in Daqing oilfield company, the multiple characteristics of pore structure in tight sandstone reservoirs are quantitatively studied by the two parameters of fractal zone and fractal dimension. The results show that the microscopic pore structure of the tight sandstone samples has multiple fractal features and the numbers of fractal zones can characterize the heterogeneity of formation. The number of fractal interval is the same as the peak value of pore radius distribution curve. The more fractal interval, the stronger the heterogeneity, and the worse the porosity and permeability of reservoir. For the same sample, the larger the pore radius for fractal zones is, the stronger the heterogeneity of pore structure is. For different samples, the larger the comprehensive fractal dimension is, the more the fractal zones are and the worse the porosity and permeability of formation become.

Key words: Tight sandstone, Pore structure, Multiple fractal features, Fractal zone, Fractal dimension, Quantitative characterization