The Study of Gas-water Two-phase Percolation Model on the Low-permeability Sandstone Gas Reservoirs

The obvious characteristic of low-permeability water-bearing gas reservoirs is that gas and water produce at the same time. Because of the gas and water two-phase flow, the percolation mechanism becomes more complex and the establishment of gas-water percolation mathematical model becomes more difficult. According to the percolation mechanism, this paper divides the vadose region into three zones, non-Darcy two-phase flow, Darcy two-phase flow, and single-phase gas flow, and establishes different mathematical models according to percolation characteristics in different intervals. The advantages to divide the vadose region are obvious, the percolation mechanism in each interval is very clear, so it is easy to establish and solve the mathematical model in each region.