The impact of pore size distribution data presentation format on pore structure interpretation of shales

Understanding the nature of pore structures in unconventional reservoirs such as shale oil/gas can assist in evaluating the storage potentials and reveal transport mechanisms. Pore size distribution is one of the most importance pore structure parameters which needs to be evaluated accurately and presented in various formats to provide more in-depth information from the rocks. In this paper, several shale samples were collected and analyzed by using N2 adsorption and high-pressure mercury intrusion. Three different presentations of the pore size distributions: incremental pore volume versus diameter (DV), differential pore volume versus diameter (DV/Dd) and the log differential pore volume versus diameter (DV/DlogD) were calculated from these two different methods, respectively. The comparison results showed that different presentations from the same sample could demonstrate various type of important pore information. The DV curve is largely depended on the experimental data spacing while the other two presentations do not. The DV/Dd curve could amplify the role of smaller pore ranges while the DV/Dlogd would represent the importance of the larger pore ranges. The multifractal analysis showed that the heterogeneity index calculated from the DV/Dd curve is much larger than the heterogeneity index from the DV/Dlog curve. It was concluded that DV/Dd is more suitable for characterizing the pore size distribution from N2 adsorption while DV/Dlogd works better for the high-pressure mercury intrusion.Cited as: Liu, K., Ostadhassan, M. The impact of pore size distribution data presentation format on pore structure interpretation of shales. Advances in Geo-Energy Research, 2019, 3(2): 187-197, doi: 10.26804/ager.2019.02.0