Reservoir pore structure has an important influence on seepage capacity and oil production capacity. Mercury injection experiment is an important method to study reservoir pore structure, but it cannot be carried out in large quantities due to factors such as limited number of cores, high experiment cost and mercury toxicity. Through the analysis of the mercury injection experiment data, it is found that a series of mercury injection pressure is generally a fixed distribution, and the adjacent mercury injection saturation has a good correlation. As long as a mercury injection saturation of a depth point is predicted, and the entire pseudo capillary pressure curve can be predicted for that depth. XGBoost is adopted to predict the mercury saturation, and then the pore throat radius spectrum is obtained. The rock surface relaxation rate is determined by overlapping the pore-throat radius spectrum of the mercury injection experiment and the T₂ spectrum of the NMR experiment, and the two cut-off values for distinguishing small, medium and large pores on the T₂ spectrum are converted into the two cut-off values of the pore-throat radius spectrum. Using two cut-off values to divide the pore throat radius spectrum into three parts, the pore structure index R_{c_index} is proposed. This parameter has a good correlation with the oil layer production measured by the cable formation tester. It is concluded that the pore structure index R_{c_index} predicted by conventional logging curves can continuously predict reservoir production and guide follow-up measures such as test layers selection.