| The Weixinan Sag is the main oil producing area in the South China Sea, and its first member is one of the main oil and gas reservoirs. Due to the influence of sedimentary conditions and stress, fault + lithologic reservoir is mostly developed in Liuyi member. Weizhou n oilfield is a fault + lithologic reservoir formed in the first member of Liuhe formation. The seismic event axis of the oilfield is very continuous in the second oil formation of the first member of Liuhe formation. However, the actual drilling meets the water layer in the high part and the oil layer in the low part, which is shown as different sand bodies. The continuity of seismic event axis is excellent, and there are still different sand bodies, which brings great challenges to geophysical research. In order to solve this problem, many methods are used to study the fine characterization of the sand body of the oil formation. Firstly, the seismic resolution of the oil formation is analyzed from the seismic data. It is found that after the resolution of the existing seismic data is less than the thickness of the sand body of the oil formation, the Spectral Blue is used to improve the seismic resolution, so as to identify the distribution of sand body between wells of the oil formation, but this method does not effectively solve the oil-water problem. Secondly, based on the high-resolution seismic data, the geophysical inversion method is used to solve the problem, and the conventional post stack wave impedance and waveform indication inversion are used to study the fine sand body. Compared with the conventional wave impedance inversion, the waveform indication inversion resolution is higher and better than the drilling temperature. The waveform indication inversion results of Weizhou n oilfield show that the high and low parts are different sand bodies, which effectively solves the problem of oil-water contradiction in the oilfield and points out the layout direction of subsequent well locations.