Determination of Favorable Lithofacies for Continental Shale Gas: A Case Study of the Shahezi Formation, Changling Fault Depression, Songliao Basin

In order to determine the optimum lithofacies for continental shale, reservoir characteristics of different types were studied based on a series experiments. The lacustrine organic-rich shale Shahezi Formation is divided into siliceous (ORS), argillaceous (ORA), calcareous (ORC), and mixed (ORM) shales. ORS, ORA, ORC, ORM shales all carried out comprehensive comparative analysis. results showed that moderate content clay minerals (45%) can significantly improve porosity, high low mineral contents are not conducive improvement porosity. tends have better pore connectivity than ORS ORA shales, ORC has poorest pore-throat in micron-size. Internal pores bitumen shrinkage cracks dominant type well developed two less shale; however, dissolution those Inorganic well-developed but organic not. Organic inorganic tend be connected other three types, which could help gas storage capacity. may more irregular surfaces lower liquid/gas surface tension. higher capillary condensation likely occur shale. offers fewer adsorption sites CH 4 weak heterogeneity structure. Therefore, most favorable enrichment development, good connectivity, brittleness, strong capacity, followed by worst.