Comparative study on pore characterization methods of marine and continental transitional shale reservoir

Objective The pore system of shale plays an important role in shale reservoir evaluation. There are many experiments to characterize the pore system. Different experiments have advantages and limitations, and are restricted by different areas and strata samples.Methods In this paper, CO₂ adsorption, N₂ adsorption, high-pressure mercury injection experiment and nuclear magnetic resonance experiment are used to study the shale samples of Shanxi Formation in Ordos Basin, In addition, the pore characterization results of Taiyuan Formation shale samples in Qinshui Basin are compared, and the applicability of different experiments to the marine terrestrial transitional shale is analyzed.Results For different experiments of the marine terrestrial transitional shale reservoir, the characterization advantage interval is 0.01~40 nm, 0.3~1.1 nm, 2~50 nm, respectively; The MIP advantage range is > 50nm. The experimental range is MIP, NMR, N₂ adsorption, CO₂ adsorption from large to small; the test accuracy and the highest resolution are NMR, CO₂ adsorption, N₂ adsorption, MIP from high to low.Conclusions Compared with the fluid injection method, NMR has more advantages in characterization when there are closed pores and bound water in the pores, resulting in different selection of characterization advantage range.