Reserch On Resistivity Model Of Tight Oil Reservoirs In Daqing Oilfield

With the advancement of shallow oil exploration in the SONG-LIAO basin, the objects of exploration and development have become increasingly complex, and the difficulty of exploration is also increasing. Daqing tight sandstone reservoir is characterized by low porosity, low permeability, high clay and calcium content, complicated pore structure, microporosity development and the characteristics of high irreducible water saturation. These characteristics make the conductivity of the tight sandstone reservoir in the area is very different from that of conventional reservoir, and it is a non Archie relation.Based on the experimental data and particle size analysis of the reservoir in the X formation in the A area, this paper studies the conductive rule of tight sandstone reservoir and the main influence factors. The results shows that the conductivity of rock decreases as the pore structure is worse, shale content decreases and the content of calcite increases.The experimental results prove that the effective medium symmetrical conductivity theory and the modified equivalent rock element conductivity theory can be used to describe the non Archie phenomenon of tight reservoir. According to the research results of tight reservoir conductive characteristics and tight oil reservoir characteristics, considering the influence of the factors such as shale, calcium and pore structure on the conductivity of tight reservoir, and the difference of conductive pattern between tight oil reservoir and the conventional reservoir, and basing on the effective medium theory and modified equivalent rock element theory, the tight sandstone reservoir saturation model is established for the Daqing tight sandstone reservoir, and the parameters of the model were analyzed theoretically. The pore structure of tight sands is classified by the mean radius and the ratio of non-efficient flow porosity and efficient flow porosity. On the basis of classification, the formulas of the pore structure efficiency and pore tortuosity are established with optimization technology and the efficient flow porosity formula. And the parameters in the model are determined by using the data of core electricity experiment and well logging data, and the method of calculating the water saturation is given. Comparative analysis of the advantages and disadvantages of tight sandstone reservoir saturation model and models such as three-pore conductivity model and Archie equation were conducted in theory, The accuracy of reservoir water saturation calculated from each saturation model were compared with that the core analysis of sealed cored well, and it is proved that the tight sandstone reservoir saturation model is more suitable for the tight sandstone reservoir in Daqing. Based on the resistivity model of tight sandstone, the actual logging data of tight sandstone reservoir in this area is processed, and the results show that the model can be well used in the well logging interpretation and evaluation of tight sandstone reservoirs in Daqing.