Characterization of Shale Pore Structure Using CT Scanning Technology: A Case Study in Ordovician Wulalike Formation of Ordos Basin

An accurate understanding of the pore structure of shale is the key to recognizing the gas accumulation cognition, which benefits the exploration of gas production. The significant achievement in the Silurian Longmaxi Formation of the Sichuan Basin has inspired the exploration of shale gas in Ordos Basin. However, the knowledge about the pore structure of shale in the Ordos basin still needs to be clarified. In this study, computerized tomography (CT) was applied to investigate the pore characterization of shale gas in the Ordovician Wulalike Formation of the Ordos basin. Through threshold partitioning and 3D reconstruction, the results show that the percentages of the pore, microcracks, organic matter, inorganic matter, and pyrite are 6.83%, 0.21%, 82.02%, 10.40%, and 0.54%, respectively. The shale is mainly composed of inorganic matter. Moreover, the microcracks characterized with scalloped, spatula and irregular shapes are about to split off the shale sample. Reconstructed 3D models of cracks show that little connectivity happens in the organic matter, but more occurs in the inorganic matter. The information obtained from this study can provide a foundation for understanding the shale pore structure in the Ordos basin, guiding the company staff to exploit the shale gas effectively.