The feature of the microscopic pore structure and its influence on oil displacement efficiency in Chang 6 Reservoir in Jiyuan Oilfield of Ordos Basin

Taking the Chang 6 typical tight sandstone reservoir in Jiyuan oilfield as an example,the authors make a detail research on the feature of the microscopic pore structure and its influence on the oil displacement efficiency,with a series of experiments,including the techniques of physical properties,casting thin slice,the SEM,particle size,high pressure mercury penetratio and water drive displacement test with real microscopic sandstone models,aiming at several problems in Jiyuan Oilfield of Ordos Basin,strong heterogeneity,complex micro-pore structure,its effect on saturation of mobile fluid and so on. The research shows that the primary pore of the reservoir space is the original intergranular pore and the secondary pore is the feldspar solutionpore. Based on the capillary pressure curve and its corresponding parameters,the authors divide the pore structures into four types. Different pore structure corresponds to different reservoir space. Affected by its micro pore structure,the reservoir capacity and percolation ability of the reservoirs get worse successively. Different pore structure corresponds to different waterflooding paths and oil displacement efficiency. Pore throat radius is the key factor that affects the oil displacement efficiency. The influence of permeability and porosity on oil displacement efficiency becomes worse in turn,while the oil displacement efficiency has a good positive correlation with the liquid producing of well testing. Comprehensive analysis shows that reliable data can be provided to the scientific development of reservoir by applying the relationship between the feature of the microscopic pore structure and the oil displacement efficiency.