## 3 Analysis of Experimental Results
### Water Invasion Simulation Experiment for Multi-Well Development of Fracture Model
The relationship between waterflood efficiency and recovery rate of the fracture-high-permeability zone model is shown in Figure 14. After further analysis, it was found that although there were differences in water avoidance height between simulation well 2 and simulation well 3, the bottom hole pressure of these two wells was relatively close in the late stage of water invasion due to the presence of a high-permeability zone between the two wells. Figure 12: Variation in water saturation of the fracture model at the end of the experiment. (**a**) Three times water body; (**b**) seven times water body. Figure 13: Relationship between bottom hole pressure and recovery rate of fracture–high-permeability zone model. (**a**) Three times water body; (**b**) seven times water body; (**c**) seven times water body (shut-in after water breakthrough). As shown in Figure 13b, under the seven times water body condition, the shape of the relationship curve between recovery rate and bottom hole pressure is down-concave. The water invasion rate of the fracture-high-permeability zone model was significantly faster than that of the fracture model under the same water body multiple (Figure 15). Because it is difficult for the peripheral gas to break through the water invasion area, the ultimate recovery rate decreased to 33.3%, and the overall waterflood efficiency was 29.9%, which is lower than the fracture model with the same water body multiple (Figure 14). As shown in Figure 13c, under the seven times water body condition (shut-in after water breakthrough), the curve shape of the relationship between the recovery rate and the bottom hole pressure at the early stage of water invasion was almost the same as that when the well was not shut in after water breakthrough. Simulation well 3 and simulation well 2 were shut in immediately after the water breakthrough, resulting in a rapid flow of water to the gas wells at high positions. The ultimate recovery rate was 28.3%, and the overall waterflood efficiency was 25.3% (Figure 14), lower than the recovery rate without shut-in after the water breakthrough. Meanwhile, the low-position gas well was shut in after the water breakthrough, and the bottom hole pressure gradually increased. As shown in Figure 16a, the water-gas ratios and water breakthrough times of simulation well 2 and simulation well 3 were close under the condition of three times water  
Figure 5:0 Relationship between waterflood efficiency and recovery rate of fracture–high-permeability zone model. Figure 5:1 Comparison of overall water invasion rate. body. After further analysis, it was found that continuous water production after water breakthrough can delay the water breakthrough time of high-position gas wells and reduce the water-gas ratio of high-position gas wells. Compared with the water-gas ratio of three times the water body, the larger the water body multiple, the stronger the water invasion energy, the higher the overall water-gas ratio, and the earlier the water breakthrough time under the same gas recovery rate, which is consistent with the analysis conclusion of the fracture model (Figure 16b). However, under the same water body multiple, the fracture-high-permeability zone model had a higher overall water-gas ratio than the fracture model. The water breakthrough times for simulation wells 3, 2, and 1 corresponded to 14.4%, 21.3%, and 27.7% of the overall recovery rate of the model, respectively. Furthermore, the corresponding water-gas ratios at the experiment end of the three simulation wells were 34.5, 29.0, and 4.8, respectively. As shown in Figure 16c, with the immediate shut-in of the gas well after the water breakthrough, the overall water production of the gas reservoir decreased, and the water-free production period increased. However, the water body quickly flowed toward the high-position gas well, reducing the recovery rate of the gas reservoir, which is consistent with the conclusion of the shut-in analysis after the water breakthrough in the fracture model.