# Quantitative Scale Analysis of the Channel Bar in a Braided River and Its Internal Architecture
## 3 Results
### Quantitative Study on the Internal Architecture Elements of the Channel Bar  
#### 3.3.1 Calculation of the Size of Single Accretion  
The focus of the identification of the internal of accretion is the identification of the interlayer. Under the existing dense well pattern conditions, interlayers which are a few centimeters thick can be intuitively identified according to the core data of the core well. Combining with the logging curve of the dense well pattern in the development zone, the interface identification of the accretion architecture becomes more meaningful [36]. There are three types of interfaces of the internal accretion architecture of channel bar, namely, calcareous interlayer interface, silty interlayer interface, and mud gravel interlayer interface. Among them, the internal silty interlayer is the main phase marker that divides the vertical deposited sand. Due to the different hydrodynamic conditions and sedimentary environments, the development of different parts of the silty layer is also different. Combined with the analysis of the data of the 1-42 well in the south five district (Figure 9), it can be seen that the silty layer mainly includes two types, namely, the argillaceous silty layer and the physical silty layer. The lithology of the argillaceous silty layer is dominated by mudstone and silty mudstone, with a slightly thicker thickness of about 0.5 m. It mainly develops in the upper part of the sand body of the channel bar, which is a product of the period when the hydrodynamic conditions are weak. The lithology of the physical silty layer is mainly siltstone, argillaceous fine sandstone, etc., which has a certain porosity and permeability, but it is much different from the physical properties of the upper and lower vertical deposited sand, and the thickness is thinner than the argillaceous silty layer, generally about 0.2 m. The silty layer on the core is mostly manifested as the sedimentation of a small number of fine particles with small thickness sandwiched in the thick layer of sandstone. The resistivity curve and the natural gamma curve have obvious returns, and the natural potential curve also has slight returns. The degree of curve return is positively correlated with the thickness of the silty layer. The larger the thickness, the greater the curve return amplitude. In addition, due to the influence of hydrodynamic erosion, the vergence direction and the dip angle of the silty layer are the same as all poluvial bodies on the channel bar. Figure 8: Plane graph of reservoir architecture facies of the braided river in the PI3 sublayer. According to [PERSON], [PERSON], et al. [37], the interlayer in the center of channel bar is always approximately horizontal. In the long axis direction, the interlayer facing the water is slightly steeper and the back side is gentler, while the interlayer in the short axis direction is slightly inclined to the two wings of the channel bar. According to the principle of trigonometric function, combined with the comparison diagram of the skeleton profile of single channel bar well tie (Figure 10), it is obtained that in the channel bar in PI3 layer, the inclination angle of the accretion interface in the direction of the long axis is 0.78-1.32\({}^{\circ}\), and the inclination angle of the accretion interface in the direction of the short axis is 2.02-3.78\({}^{\circ}\). Figure 10: Spatial distribution characteristics of the architecture elements within the channel bar. Figure 9: Collective logging diagram of a typical cored well in the PI3 sublayer, (**a**) parallel to the bedding, silty mudstone of core image; (**b**) fine sandstone of core image; (**c**) sandy conglomerate of core image; (**d**) parallel to the bedding, oil-rich fine sandstone of core image; (**e**) argillaceous siltstone of core image; (**f**) oblique bedding, sandstone of core image; (**g**) oil patch sandstone of core image.