Physical Simulation and Law of Interlayer Interference in Multi-Layer Combined Production of Gas Reservoirs with Pressure Difference

To address interlayer interference during multi-layer commingled production in gas reservoirs with pressure differences, this study investigates the low-permeability gas reservoir in the central Linxing area of the Ordos Basin. High-temperature, high-pressure physical simulation experiments were conducted to systematically study single-layer, two-layer, and three-layer commingled production under different pressures (13, 15, and 17 MPa). A large-scale physical simulation system, capable of withstanding 100 °C and 50 MPa, was constructed for the dynamic monitoring of multi-layer commingled production. This system accurately characterized the instantaneous gas production, cumulative gas production, and pressure drop behavior of individual layers under both single-layer and commingled production conditions. The results indicate that significant interlayer interference occurs during multi-layer commingled production. This interference is primarily manifested as a capacity inhibition effect, where the high-pressure layer suppresses the production of the low-pressure layer. Typical phenomena accompanying this effect include ‘backflow’ and ‘staggered production peaks’. Quantitative analysis indicates that the cumulative gas production for two-layer and three-layer commingled production is 3.2% and 9.06% lower, respectively, than the summed production from equivalent single-layer operations. Notably, in the three-layer commingled production scenario, the productivity of the low-pressure layer (Q5) was reduced by 19.87%, a significantly greater loss compared to the 4.39% reduction observed in the high-pressure layer (T2). Furthermore, the study demonstrates that the severity of interlayer interference is positively correlated with the interlayer pressure difference. Additionally, as the number of commingled layers increases, the interference effect exhibits a superimposed enhancement characteristic.