## 3 Results and Discussion
### Interlayer Interference Time and Backflow Gas Volume  
The interlayer interference time is defined as the total duration from the beginning of commingled multilayer production to the complete discharge of backflowed gas from the low-pressure layer, and it encompasses the duration of the backflow from a high-pressure layer to a low-pressure one and backflowed gas discharge from the low-pressure one. In other words, the termination of interlayer interference coincides with the initiation of discharge for the original gas saturation in the low-pressure layer. The backflow duration refers to the period during which gas in a high-pressure layer enters a low-pressure layer, corresponding to the duration of the previously mentioned production stage with stable  
Figure 2: (**a**) Instantaneous gas flow rate and (**b**) production contribution ratio curves for the commingled production of Q5 + H8 layers. interference between interlayers. The backflow gas discharge time refers to the duration starting from the time at which backflowed gas from the high-pressure layer is being produced from the low-pressure layer until all the backflowed gas is completely discharged. Due to the significant differences in interlayer pressure and properties, the backflow time and gas discharge time were prolonged during the commingled Q5 + H8 layer production. The pressure and cumulative gas production variation curve during the commingled Q5 + H8 layer production, as depicted in Figure 5a,b, illustrates that the Q5 layer experienced backflow with an increase in pressure and that there was a rapid  
Figure 3: (**a**) Instantaneous gas flow rate and (**b**) production contribution ratio curves for the commingled production of H8 + BX layers. decrease in pressure on the H8 layer. The backflow duration was 169 min, accounting for 9.84% of the total production time of 1718 min. The backflow gas volume from layer H8 to layer Q5 amounted to a total of 1511 mL under standard conditions, representing 61.17% of the initial gas content in layer Q5. The maximum instantaneous backflow rate can reach 70.93 mL/min, which is equivalent to 13.38 times the total gas rate at the outlet. The pressure between the two layers gradually approached equilibrium, entering a stable production stage where both Q5 and H8 layers commenced simultaneous gas production, resulting in a concurrent reduction in pressure. At 752 min, the gas backflowing into layer Q5 was completely produced. The total duration of backflow and backflowed gas discharge time amounted to 752 min, representing 43.79% of the total gas discharge time of 1718 min. Figure 4: (**a**) Instantaneous gas flow rate and (**b**) production contribution ratio curves for the commingled production of four layers. The interlayer difference in H8 + BX layers was relatively smaller compared to that of Q5 + H8 layers. Although there was interlayer interference during commingled two-layer production, the duration of interference was relatively short in comparison to that of the total gas discharge time. As can be seen in Figure 6a,b for the commingled H8 + BX layer production, the durations of backflow and subsequent backflowed gas discharge were found to be 11 min and 41 min, respectively, accounting for a mere 0.61% and 2.28% of the total gas discharge time. The backflow gas volume and rate were relatively low, with a maximum backflow rate of merely 1.46 times the total gas production rate, while the  
Figure 5: (**a**) Pressure change and (**b**) accumulated gas production curves for the commingled production of Q5 + H8 layers. corresponding backflow volume accounted for only 0.88% of the initial gas content. Such a backflow phenomenon was not prominent in the commingled S1 + TY layer production due to unobvious interlayer pressure differences, and both the backflow rate and volume were minimal. The above analysis reveals that, in the presence of a significant difference in interlayer pressure, there exists an increase in both gas backflow volume and maximum instantaneous backflow rate.