CHARACTERISATION OF NON-ISOTHERMAL GAS-WATER TWO-PHASE DISPLACEMENT BASED ON THE PHASE FIELD METHOD

This paper employs a two-phase flow numerical method based on the coupling of Navier-Stokes and Cahn-Hilliard equations, coupled with a surface tension model and a heat transfer model, to complete the quantitative calculations of fluid dynamics and heat transfer while also using a non-homogenous approach to clarify the dynamic replacement characteristics of gas-water two-phase flow in porous media under non-isothermal conditions. At the same time, we accurately characterize the two-phase flow process under the non-isothermal heat-fluid coupling in the porous medium by using the non-homogeneous model to characterize the true pore space characteristics. The fluid's velocity and pressure are calculated using the Navier-Stokes equation, and the temperature distribution at each instant is obtained by combining the heat transfer equation and the Cahn-Hilliard equation to accurately simulate the evolutionary characteristics of phase separation; The nodes of the temperature coupling and joint flow coupling are used to realize the full coupling in terms of mass, momentum, and energy; The algorithms employ an adaptive mesh method, so that the distribution of mesh points is the grid point distribution is always associated with the physical solution thanks to the algorithm's adaptive grid technique, which increases the solution's high accuracy. The study reveals that: the fluid pressure change trend in the large hole is smooth, while the fluid velocity in the narrow hole throat is larger and fluctuates sharply; The gas injection pressure increases, the time it takes for the gas to breakthrough is shortened, the temperature's heat conduction rate is accelerated, and the repellent efficiency decreases after the gas breakthrough; the higher the gas injection pressure, the more the water interferes with the gas flow capacity; The best water-repellent effect is obtained when the injection pressure difference allows the gas phase to penetrate the fine pore space while also being relatively less disturbed by the flow, higher injection pressures make the interference of water with the gas flow capacity worse.