Abstract:In order to study the pore structure and fractal characteristics of different types of tight sandstone reservoirs in Fuyu oil layer, we selected 8 samples from Fuyu oil layer K1q3 and K1q4 for analysis based on the experimental data of high pressure mercury injection, combined with physical property test and mineral analysis to determine mineral components. Three types of reservoirs were classified according to the shape difference of mercury injection curve, pore throat radius and displacement pressure characteristics: low displacement pressure-micro throat type, medium displacement pressure-micro throat type, and high displacement pressure-adsorption throat type. The fractal dimension of pore structure of tight sandstone reservoir was calculated and the influences of reservoir physical characteristics, pore throat structure parameters and quartz and calcite content on the fractal dimension were discussed. The results showed that all types of reservoirs presented two-stage fractal characteristics, and two fractal dimensions were obtained: D1 ranged from 2.9908 to 2.9956, with an average of 2.9933; D2 ranged from 2.5738 to 2.6664, with an average of 2.6101. The complexity and heterogeneity of pore throat structure in Fuyu oil reservoir in Daqing have a strong control on the tight reservoir space and seepage capacity. The larger the fractal dimension is, the more complex the pore throat structure is and the stronger the heterogeneity is.