## 4 Results and Discussion
### Characteristics of the Shale Reservoirs and Their Influencing Factors
#### 4.3.2 Shale Pore Types
(**b**) Organic pores (yellow arrow) developed from solid bitumen filling the intercrystalline pores of a pyrite framboid (1229.6 m depth). (**c**) Organic pores (yellow arrow) developed from solid bitumen filling interparticle pores (1234.2 m depth). (**d**) Organic pores (yellow arrow) developed from organic matter and clay mineral assemblages (1234.2 m depth). (**e**) Elliptical to worm-like organic pores (yellow arrow) (1237.2 m depth). (**f**) Collapsed and interconnected organic pores (yellow arrow) (1237.2 m depth). (**g**) Organic pores (yellow arrow) are not developed within organic matter but at its edge (1252.9 m depth). (**h**) Organic matter (yellow arrow) without internal pores but with contracted slit pores at its edge (1252.9 m depth). (**i,j**) Small organic pores (yellow arrow) are evenly distributed throughout organic matter (1244.2 m depth). (**k**) Organic pores of heterogeneous sizes (yellow arrow) are unevenly distributed throughout organic matter (1249.2 m depth). (**l**) Oriented organic matter and mineral particles, showing fluid shapes (1249.2 m depth). Moreover, the high organic matter content, the relatively low amounts of brittle minerals such as quartz, and the large amounts of organic matter mixed with rigid minerals and clay minerals in fluid shapes (Figure 8l) indicate that these shales were affected by compaction or tectonic stress, which may have impacted the organic pores. (2) Non-organic pores  
Non-organic pores in the Dalong Formation shale samples were less developed than organic pores; intraparticle, intercrystalline, and interparticle pores were identifiable. Intraparticle pores were typically formed within brittle minerals such as quartz, feldspar, calcite, and dolomite via dissolution during diagenesis [50]. The Dalong Formation shales contain small amounts of carbonate minerals; the large amount of acidic fluid produced from the organic matter during hydrocarbon generation dissolved calcite particles to form numerous dissolution pores (Figure 9a). The intraparticle pores formed by the dissolution of brittle minerals were then filled by migrating solid bitumen, forming a film of homogeneous thickness on the pore surfaces (Figure 9b). Intraparticle pores were circular and quadrilateral and generally around 300 nm in size. Intercrystalline pores were mainly formed in pyrite framboids or unfilled pore spaces between recrystallized minerals during diagenesis (Figure 9c); these pores had irregular polygonal or elongated shapes and typical diameters of 100-500 nm. Intergranular pores mainly include interparticle pores between rigid minerals (Figure 9d), interparticle pores between minerals and organic matter (Figure 9e), and interlayer pores in clay minerals (Figure 9f,g). Intergranular pores are mostly irregular and polygonal, triangular, or parallel-plate shaped, are well connected, and are 50-500 nm in size. Figure 9: Characteristics of non-organic pores and microfractures in the Dalong Formation shale samples from well ED-2. (**a**) Intraparticle pores developed within calcite (1244.2 m depth). (**b**) Intraparticle pores filled with a bitumen layer of homogeneous thickness (1249.2 m depth). (**c**) Interparticle pores developed between recrystallized dolomite grains (1234.2 m depth). (**d**) Interparticle pores developed between quartz and feldspar grains (1229.6 m depth). (**e**) Interparticle pores developed between quartz and organic matter (1229.6 m depth). (**f**) Slit pores between clay minerals (1244.2 m depth). (**g**) Elongated and parallel-plate pores between clay minerals (1252.9 m depth). (**h**) Contraction fractures developed at the edge of organic matter (1229.6 m depth). (**i**) Diagenetic fractures developed between rigid minerals and clay mineral grains (1234.2 m depth). (**j**) Intraparticle fractures developed within a pyrite framboid (1244.2 m depth). (**k**) Intraparticle fractures developed within quartz grains (1237.2 m depth). (**l**) Interparticle fractures developed between mineral grains (1249.2 m depth). 3.