A new dynamic model of supply boundary at low pressure in tight gas reservoir

Tight gas is a clean and low-carbon energy with great development potential. However, in the middle and late stages of development of tight gas reservoirs, there are characteristics of low pressure, low production and high water cut. At present, there are few studies on the dynamic supply boundary considering the threshold pressure gradient, reservoir and fracture stress sensitivity and slip effect for the gas-water two-phase model of tight gas reservoirs. In order to improve the assessment of the supply boundary and production capacity features of tight gas wells at low pressure, a new coupling model of gas-water two-phase was established in this paper and the threshold pressure gradient, stress sensitivity and slip effect are taken into account the built model. Subsequently, the steady-state substitution method and the material balance method were used to develop the supply boundary calculation model. Finally, an analysis is done on how the supply boundary is affected by the threshold pressure gradient production, stress sensitivity and production pressure difference. The results demonstrate that, in contrast to the slower propagation observed in the matrix zone, the supply boundary propagates relatively quickly within the fracture modification zone. The threshold pressure gradient and stress-sensitive increase the resistance of gas seepage and delay the propagation of the supply boundary, which reduces the production of gas well. The propagation of the supply boundary accelerates with increasing production pressure difference, but the pressure difference's effect decreases. The production of gas is significantly impacted by the threshold pressure gradient, stress sensitivity and production pressure difference. Efficient production of tight gas reservoirs necessitates minimizing water production and preserving formation pressure.