Study On Pore Structure Of Low Permeability Sandstone Reservoir Based On Constant Velocity Mercury Intrusion

The research methods of reservoir rock pore structure are mainly divided into image analysis method and fluid displacement method.Scanning electron microscopy,nuclear magnetic resonance(NMR)and constant rate mercury injection are the most important core analysis techniques widely used on studies of pore structure.This papert apply these techiques to research the pore structure of EN low permeability sandstone reservoir.The main work accomplished and knowledge gained are as follows:(1)Based on the analysis of the casting thin sections and scanning electron microscopy,the distribution of pore throat,the aspect ratio of pore to throat,the distribution of clay minerals and the degree of particle dissolution of EN low permeability sandstone reservoir are obtained;(2)The interfacial phenomena in the pore structure are analyzed theoretically;(3)The processing and analysis methods of raw data form constant rate mercury injection are discussed,and the distribution characteristics of the pore throat invaded by mercury under different displacement pressure range are obtained;(4)The bimodal distribution of EN low permeability sandstone reservoir was found resulting from by comparison of pore throat distribution based on constant rate mercury injection and that of NMR.(5)The pore structure of reservoir to research was evaluated with the help of advantages of both const pressure and constant rate mercury injection to find the main throat radius of this reservoir is less than 1?m;(6)The influences on results of experimental factors were analysed based on the simulation of consta rate mercury injection with the help of random pore network simulation;(7)The pore structure and movable fluid space of EN low permeability reservoir were studied by combination of constant rate mercury injection and NMR based on the results obtained.This research takes the exploration of correct application of constant rate mercury injection experiment in low permeability reservoir cores as the core,through a variety of experimental methods and pore network simulation,to further deepen the understanding of the constant rate mercury injection experiment and accurately evaluate the pore structure of EN low permeability reservoir rocks.