Numerical simulation of gas-water two-phase seepage flow based on level set method

Abstract

The mechanism of gas-water two-phase percolation was previously characterized based on percolation experiments. However, the changes in the gas-water interface and the volume fraction of the two phases in the process of gas-water percolation in porous media cannot be accurately described by experiments. This paper uses core casting thin sections and AutoCAD software to establish a digital core. Based on the idea of level set, a two-dimensional gas-water seepage model in microscopic pores is established. The finite element numerical simulation software is used to solve the model to describe the gas. The changes of the water two-phase interface are visually displayed. At the same time, Darcy’s law is used to compare the relative permeability curve obtained from the gas-water two-phase seepage experiment with the relative permeability curve obtained from the gas-water two-phase seepage finite element simulation. The results show that the gas-water two-phase seepage experiment and the gas-water two-phase seepage finite element numerical simulation have basically the same characterization of the seepage ability of porous media. There is obvious fingering phenomenon in the process of gas flooding, and the gas preferentially passes through the large pore throat. The smaller the pore throat, the greater the velocity of gas passing through the pore throat. The gas-water two-phase interface change described by the numerical simulation of the gas-water two-phase flow based on the digital core is more reliable.

Effect of bubble volume on the sweeping velocity of air bubbles in horizontal pipelines in water supply system

“…The interface tracking methods (Jafari and Okutucu-Özyurt, 2016;Wu et al, 2021;Wang et al, 2023) such as, MAC (marker and cell technology) model (Santos et al, 2012), etc., have been introduced. The interface capture methods such as the level-set (Zhang et al, 2013;Zhai et al, 2021;Amin and Majid Eshagh, 2020), VOF (volume of fluid) (Ye et al, 2020;Mohammad et al, 2020;Li et al, 2021), and CLSVOF models also have been widely used. Song (2011) proved that when computing the sweeping velocity of air bubbles using convection transport equation, the precision of air-liquid two-phase flow using the CLSVOF model is much more accurate than that of the level-set model and the VOF model.…”