A comparative analysis of mercury intrusion and nitrogen adsorption methods for multifractal characterization of shale reservoirs in northern Songliao Basin

The northern Songliao Basin is shale-oil-rich with high exploration potential. However, its heterogeneity challenge reservoir characterization and evaluation, impeding exploration and development efforts. Thus, analyzing continental shale's pore structure and heterogeneity is crucial. This work utilizes High-pressure mercury intrusion (HMIP) and low-pressure N₂ adsorption (LPN₂A) methods to analyze the multifractal characteristics of shale pore structures at different depths. Results indicate that there is no significant correlation between the pore structures determined by the two methods. However, the heterogeneity of the pore structure obtained by the HMIP method is stronger than that by the LPN₂A method. The study also found that as the total pore volume increases, the heterogeneity of the pore structure increases, while the pore connectivity is not significantly correlated with the pore volume. In addition, mineral content has a significant impact on the heterogeneity of pore structure and pore size distribution, especially the content of quartz.