# A New Method of Geological Modeling for the Hydrocarbon Secondary Migration Research
## 4 Reservoir Modeling of the Sangonghe Formation in the Central Junggar Basin
### Structure and Facies Modeling  
Based on the data and knowledge of the sedimentary facies, structure and reservoir heterogeneity in the MXZ area of the Junggar Basin, the geological model of the heterogeneous reservoir in the Sangonghe Formation, is constructed by using the above-mentioned reservoir modeling method. Furthermore, the favorable target area is evaluated and optimized by using the relevant parameter. On the basis of single-well sedimentary microfacies, combining sedimentary facies, logging facies, and seismic facies, it is determined that a set of braided river delta sedi  
Figure 7: Structural location map and stratigraphic development characteristics of the MXZ area. (**A**) The research area (in red rectangle) in the structure map. (**B**) The depth contours of the research area. (**C**) The stratigraphic development characteristics and the related sand-body distribution model. mentary system is developed in the Sangonghe Formation. The sandstone reservoirs are mainly distributed in the delta-front subfacies in the lower part of J1S2, and the source is mainly from the north. The submarine distributary channels are widely developed and have good continuity. A large number of front-sheet sands are developed outside the distributary channels, with fewer mouth bars developed. The upper and lower parts of J1S2 developed submarine distributary channels of the delta front and shore-shallow lake facies, which have narrow width, short length, and thin sand bodies. The middle mainly developed braided channel microfacies of delta plain subfacies, with great thickness and good continuity. The bars within the braided channels are widely developed and the flood plain partially deposits the outer part of the braided channels. In this modeling practice, an area of 25.45 km \(\times\) 18.65 km was targeted, and the sedimentary reservoirs of J1S2, J1S2, and J1S2, from top to bottom, were modeled using this 'unit element' stochastic modeling method, which collectively deposited predominantly braided delta plain and front environment with an average thickness of 121 m.  
The top structure map of each layer of the Sangonghe Formation in the MXZ area is obtained through seismic data interpretation after well-seismic calibration (Figure 8A). The structure of the study area is relatively stable, showing a monoclinic form with high north and low south. The south is influenced by the Mosauwan uplift, slightly higher in the southeast and lowest in the southwest (Figure 8B). Figure 8: Structure surfaces (**A**) and structure framework (**B**) of the second member of the Sangonghe Formation in the MXZ area. The braided unit element was chosen to represent the sediments in the target reservoirs as a whole. Unit elements and single-well sequence interface are identified by core, thin-section, and logging data. The sand ratio distribution characteristics of each layer can be obtained by using wave impedance inversion technology under the well-seismic calibration (Figure 9). According to the field outcrops and previous research results, the thickness and width-thickness ratio of the submarine distributary channel, river mouth bar, and braided bar of the Sangonghe Formation were obtained (Figure 10). The distributary channels have a thickness ranging from 3.5 to 7.8 m and a width between 180 and 535 m. The width-to-thickness ratio falls within the range of 52 to 90. The thickness of the mouth bars ranges from 6 to 14.5 m, the width of which spans from 450 to 815 m, and the width-thickness ratio is in the range of 45 to 95. The braided bars have a width spanning from 6.5 to 100 m and a length between 20 and 240 m. The aspect ratio is between 2.3 and 6.8 m. Based on the geometry size statistics of the sediments, the scale of the braided unit elements was given distributions of widths ranging from 200 to 600 m, lengths between 300 and 1000 m, and width-thickness ratios between 50 and 100.