Method Selection for Analyzing the Mesopore Structure of Shale—Using a Combination of Multifractal Theory and Low-Pressure Gas Adsorption

Nitrogen adsorption experiments have been extensively applied to shale pore structure research and evaluation. The can be quantitatively characterized in accordance with the nitrogen adsorption–desorption isotherm using various calculation models, whereas results obtained different models more effectively indicate characteristics of remains unclear. Further, there has not any unified process optimization for size distribution (PSD). In this study, Barret–Joyner–Halenda (BJH-AD) BJH desorption (BJH-DE) were used Longmaxi Formation as an example. Subsequently, density functional theory (DFT) calculations conducted on lithofacies samples. Next, parameters heterogeneity compared, consistency Cronbach’s alpha. indicated that BJH-AD model underestimated since macroscopic thermodynamic was applicable study. DFT showed multiple peaks range 1–10 nm, BJH-DE had a significant artificial peak 3.8 nm due tensile strength effect, thus suggesting is capable characterizing pores 10 lower than model. PSD curves generated three exhibited multifractal characteristics, achieved different. Moreover, studied depth by combining alpha parameters. high heterogeneity, method N2 optimal physical data analysis mesoporous range. Accordingly, curve, hysteresis loop shape, parameters, integrated generate working flow chart N2-adsorption-model optimization.