Laminar Structure and Reservoir Quality of Shales with High Clay Mineral Content in the Qingshankou Formation, Songliao Basin

This paper investigates high-maturity organic matter-rich shales with high clay mineral contents in the Qingshankou Formation, Gulong Depression of Songliao Basin, at a sub-millimeter scale, using new laminar division method based on XRF data. The influence structure reservoir quality is examined combination geochemistry, mineralogy, and pore structures. Explanatory models are established. Three types units distinguished study area differences structure. These laminae (UA), mineral-Ostracod (UB), mineral-felsic (UC). UA has illite intergranular pores, micro-fractures, diameters 0.5~2 μm. UB primarily contains Ostracod shell margin fractures, pyrite chlorite intragranular pores. UC albite Nitrogen adsorption tests show that highest content best specific volume surface area, indicating minerals main contributors to pores this type unit. 2D–3D different reveal carbonate cement widely developed UC, but dissolution less developed, result porosity two three times greater than or UC. It appears formed during transformation advanced thermal evolution stage, storage space flow channels. Thermal evolution, transformation, cementation key factors causing between units. In addition, (UA) most important for shale oil enrichment area. finding great significance accurately predicting distribution “sweet spots” guiding gas exploration.