## 3 Analysis of Experimental Results  
### Water Invasion Simulation Experiment for Multi-Well Development of Fracture Model  
As shown in Figure 5, the bottom hole pressure of the three simulation wells decreased approximately linearly with the recovery rate increase when there was no water body. However, until the end of the experiment, the maximum drawdown pressure of the three simulation wells was only 0.25 MPa, indicating that under the condition of no water body, the gas seepage resistance was low, and the ultimate recovery rate reached up to 89.12%. Figure 4: Experimental equipment and process. As shown in Figure 6a, under the three times water body condition, the bottom hole pressure does not change linearly with the recovery rate but changes in an up-concave shape with the increase in recovery rate. In addition, there is an obvious inflection point. Before the inflection point, the bottom hole pressure decreases slowly, but after the inflection point, it drops sharply. This phenomenon indicates that in the early stage of water invasion, the water body can provide some energy for gas reservoirs and delay the decrease in bottom hole pressure. In the middle and late stages of production, with the aggravation of water invasion, on the one hand, the water body quickly flowed into the reservoir along the fracture, forming a gas-water two-phase flow inside the reservoir, resulting in a sharp increase in gas seepage resistance and a rapid drop in bottom hole pressure. On the other hand, under the effect of capillary force, the matrix reservoir in the fracture area experienced imbibition and trapped gas in the matrix, generating a large amount of residual gas, which decreased the ultimate recovery rate to 58.2%, with a waterflood efficiency of 42% (Figure 7). Figure 5: The relationship between bottom hole pressure, drawdown pressure, and recovery rate. Figure 6: Relationship between bottom hole pressure and recovery rate of fracture 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 6b, under the seven times water body condition, the curve shape of the relationship between the recovery rate and the bottom hole pressure is nearly the same as that of the three times water body. Compared with the production law of gas wells at three times water body, the larger the water body multiple, the more pronounced the energy supply effect in the early stage of water invasion, and the lower the recovery rate corresponding to the inflection point. After the gas well water breakthrough, the gas and water outflowed intermittently, and waterflooding occurred eventually. It was difficult for the peripheral gas to break through the water invasion area, resulting in the ultimate recovery rate decreasing to 52.8%, and the overall waterflood efficiency was 37.2% (Figure 7). The low water body multiple provided displacement energy for the gas reservoir. The invasion of a small amount of water occupied the reservoir space of the gas, displaced some of the gas, and improved the recovery rate of the gas reservoir. With the increase in water body multiples, the water invasion energy increased, and the water body also trapped a large amount of gas through the cut-off, bypass flow, and water lock while displacing the gas. The recovery rate decreased when the water invasion was dominated by trapped gas. As shown in Figure 6c, under the seven times water body (shut-in after water breakthrough) condition, the curve shape of the relationship between the recovery rate and the bottom hole pressure at the early stage of water invasion is consistent with that when the well was not shut in after water breakthrough. When the low-position gas well (simulation well 3) was immediately shut in after the water breakthrough, the bottom hole pressure gradually recovered and rose. The average ultimate recovery rate was 38.5%, which is lower than that of the well not shut in after the water breakthrough, and the overall waterflood efficiency was 32.5% (Figure 7).