A new method for ascertaining the influx dynamic relation in water-gas producing horizontal wells

For the two phases flow of gas and water, gas will escape from the water or water will evolve from the gas, which both changes the gas reservoir flow characteristics. Based on the basic theory of permeation flow mechanics and the conformal transformation mathematical method, the 3D flow in horizontal wells is simplified into the flow in horizontal and vertical planes. Simultaneously, considering the process that the gas and water mutually dissolve and volatilize in the formation, the gas-water two phase flow mathematical model for horizontal well is inferred, and the gas-water productivity equation for horizontal wells is established. By referencing the auxiliary equation of relative permeability and the equation of material balance pressure drop of water-drive gas reservoirs, the comprehensive flow model for gas-water producing horizontal wells is built. By automatic fitting analysis of gas production, water production, tubing and casing pressure of gas wells, the integrated flow model parameters of gas-water producing horizontal wells can be obtained, and the gas-water productivity equation, gas-water flow curves, probable reserves in individual wells and water cut intensity can also be obtained. This new method avoids the limitation of relying on field test to determine the gas well productivity and provides a new theoretic method for deliverability and dynamic analysis for gas-water flow wells.