## 3 Results and Analysis
### Effect of Number of Natural Fractures  
The distribution of natural fractures plays a crucial role in influencing fracturing effectiveness within reservoirs. Therefore, this section undertook a simulation analysis to investigate the impact of varying numbers of natural fractures in the simulated target block. Based on the field data obtained from the target block, the linear density of natural fractures within the block falls approximately within the range from 0.3 to 0.8. Considering a simulated area of 60 m \(\times\) 60 m, the number of natural fractures in the model varies from 20 to 50. The simulation results obtained are shown in Figure 6.  
Figure 5: Morphology comparison results of artificial fractures under different cluster numbers ((**a**) 3D view and (**b**) top view) (C1, C3, C6, C9, and C12 refer to fracturing scenarios involving 1 cluster, 3 clusters, 6 clusters, 9 clusters, and 12 clusters, respectively).  
Figure 6 shows that with the increase in fracture density, the number of fracture elements and the total area of fractures show an increasing trend. Meanwhile, the aperture and volume of fractures seem to show a certain decreasing trend. This may be due to the increased density of natural fractures, which makes reservoir fracturing more susceptible to the influence of fractures, resulting in the formation of many low-opening shear fractures. Therefore, with the increase in natural fractures, the shear fractures generated by shear stimulation significantly increase, and the fracture area increases. At the same time, since shear fractures are mostly low-opening fractures, the visible volume of artificial fractures shows a certain fluctuation and decreasing trend.  
Figure 7 illustrates the opening of artificial fractures in reservoirs under the influence of varying natural fracture densities. As depicted in the figure, with the increase in natural fractures, the number of artificial fractures in the reservoir significantly increases, and more branches and extensions of artificial fractures occur. Simultaneously, an increase in natural fractures leads to a higher likelihood of large openings in artificial fractures near the reservoir wellbore. In addition, when the number of natural fractures increases to a certain extent, it may induce single-cluster fracturing to form a multi-cluster extended artificial fracture network. The above results indicate that natural fractures have a significant impact on the development of artificial fractures during reservoir fracturing, which may alter the position of the main fractures, the distribution of fractures near the wellbore, and the bending and branching morphology of the main fractures, thereby inducing the formation of complex fracture networks and improving the effectiveness of reservoir fracturing.  
Figure 6: Results of conventional quantitative metrics under influence of number of natural fractures ((a) number of damaged interface elements versus time; (b) fracture area versus time; (c) fracture aperture at injection point versus time; (d) maximum fracture aperture versus time; (e) fracture volume versus time; and (f) ratio of tensile failure versus time) (numbers (20, 30, 40, 50) represent quantity of natural fractures in various simulation models).