## 4 Results and Testing
### Reservoir Facies Characteristics  
#### 4.2.1 Dengying Formation 4 th Member  
The core samples, characterized by the Fractured-Vuggy type, are brownish-gray. The lithology primarily consists of microbial dolostromatolite with a range of vug sizes from large to medium, with bitumen as the predominant fill material. Core porosity varies from 2.22% to 5.27%, with an average of 3.58%, and permeability ranges from 0.33 mD to 8.96 mD, averaging 0.63 mD. The Fractured-Vuggy type is characterized by conventional logging responses, including a significantly enlarged caliper, high AC values, elevated neutron porosity, and notably low resistivity with distinct invasion characteristics (Figure 4).  
Partially cemented Fractured-Vuggy type cores are brownish-gray. The lithology primarily consists of microbial dolostromatolite with small vugs, often filled with bitumen. Core porosity varies from 2.20% to 5.36%, with an average of 3.25%, and permeability ranges from 0.28 mD to 6.78 mD, averaging 0.48 mD. Partially cemented Fractured-Vuggy type is characterized by conventional logging responses, including moderate to high AC value, significant fluctuations in neutron porosity, and notably low resistivity without distinct invasion characteristics (Figure 4).  
Pore-Vuggy type samples are light and brownish-gray, with microbial dolograinstone as the predominant lithology. Porosity in the cores varies from 1.42% to 4.51%, with an average of 2.92%; permeability ranges from 0.17 mD to 4.87 mD, averaging 0.32 mD. The Pore-Vuggy type is characterized by conventional logging responses, including slightly enlarged caliper, medium to high resistivity, inconsistent invasion characteristics, and a wide range of densities (Figure 4).  
Pore Type I samples are colored light and brownish-gray, predominantly composed of microbial dololaminite. Porosity varies from 0.26% to 3.57%, averaging 1.45%, while permeability ranges from 0.13 mD to 1.28 mD, with an average of 0.028 mD. Pore Type I is characterized by highly variable resistivity (Figure 4).  
Figure 3: Cross-plot of PC1 vs. PC2 for the Dengying Formation 4 th Member and Dengying Formation 2 nd Member.  
Pore Type II samples are light and brownish-gray, composed primarily of microbial dololaminite. Core porosity varies from 0.85% to 3.38%, with an average of 1.10%, while permeability ranges from 0.11 mD to 1.36 mD, with an average of 0.017 mD. Pore Type II is characterized by elevated natural gamma rays, high-density values, and no clear invasion characteristics (Figure 4).  
Tight Type I samples are light gray and brownish-gray, primarily composed of dolowackestone. Porosity ranges from 0% to 2.15%, with an average of 1.02%, and permeability ranges from 0.01 mD to 0.47 mD, with an average of 0.018 mD. Tight Type I is characterized by a normal caliper, high-density values, extremely high resistivity, and indistinct invasion characteristics (Figure 4).  
Tight Type II samples are light and brownish-gray, primarily composed of wackestone. Porosity varies from 0% to 1.90%, with an average of 0.25%, and permeability is below 0.01 mD. Tight Type II is characterized by a normal caliper, lower density than Tight Type I, extremely high resistivity, and no invasion characteristics (Figure 4).