## 4 Results and Testing
### Reservoir Facies Characteristics
#### 4.2.2 Dengying Formation 2 nd Member  
Fractured-Vuggy types are colored light and brownish-gray in the core, predominantly comprising large to medium vug microbial dolostromatolite. The primary fill material is bitumen. Core porosity varies from 2.12% to 9.73%, averaging 4.65%; permeability ranges from 0.56 mD to 5.88 mD, averaging 1.15 mD. Fractured-Vuggy type is characterized by a significant enlargement of the caliper, extremely high AC, high neutron porosity, distinctly low resistivity, and invasion characteristics (Figure 5).  
Figure 4: Types and characteristics of reservoir facies for the Dengying Formation 4 th Member in the study area.  
Partially cemented Fractured-Vuggy type core samples are colored light gray and brownish-gray, primarily comprising medium-vugy small-fracc microbial dolostromatolites. The primary cement phase is bitumen. Core porosity varies from 1.89% to 12.39%, with an average of 4.24%; permeability ranges from 0.37 mD to 5.87 mD, with an average of 0.87 mD. Partially cemented Fractured-Vuggy type is characterized by a significant enlargement of the caliper, greatly increased AC, significantly lower density, a wide range of neutron porosity, extremely low resistivity, and obvious invasion characteristics (Figure 5).  
Pore-Vuggy Type I samples are both light and brownish-gray, primarily composed of small-vug microbial dolograinstone. Core porosity ranges from 1.39% to 4.57%, averaging 2.18%, and permeability varies from 0.17 mD to 2.17 mD, averaging 0.20 mD. Pore-Vuggy Type I is characterized by a normal caliper, medium-to-low resistivity, subtler invasion characteristics compared to Fractured-Vuggy Type, and lower density (Figure 5).  
Pore-Vuggy Type II samples are colored light gray and brownish-gray, primarily composed of small-vug breccia dolostone. Core porosity varies from 1.15% to 5.11%, averaging 2.10%, and permeability ranges from 0.13 mD to 1.22 mD, averaging 0.16 mD. Pore-Vuggy Type II is characterized by a normal caliper, medium to high resistivity, and slight invasion characteristics. Compared to Pore-Vuggy Type I, Pore-Vuggy Type II displays a significantly lower density (Figure 5).  
Pore Type I samples are light and brownish-gray, primarily composed of fine-medium crystalline dolostone. Core porosity varies from 0.62% to 5.62%, averaging 1.66%, and permeability ranges from 0.08 mD to 4.22 mD, averaging 0.10 mD. Pore Type I is characterized by a normal caliper, elevated density values, and no invasion characteristics (Figure 5).  
Pore Type II samples appear light gray and brownish-gray, primarily comprising microbial dolograinstone. Porosity varies from 0.44% to 5.11%, averaging 1.59%, and  
Figure 5: Types and characteristics of reservoir facies for the Dengying Formation 2 nd Member in the study area.  
permeability ranges from 0.04 mD to 1.08 mD, with an average of 0.11 mD. Pore Type II is characterized by elevated gamma rays, enlarged caliper, low density, high resistivity, and no invasion characteristics (Figure 5).  
The Tight Type in core samples is light gray, primarily composed of doubackestone. Porosity varies from 0% to 2.88%, averaging 0.71%, and permeability ranges from 0 mD to 0.41 mD, with an average of 0.044 mD. Conventional logging responses show no enlargement or contraction caliper, high bulk density, high resistivity, and lack evident invasion characteristics (Figure 5).