Cessation of Darcy regime in gas flow through porous media using LBM: Comparison of pressure gradient approaches

Using three-dimensional LBM fluid model, gas flow simulated through different real porous structures obtained from micro-CT technique, using conventional pressure gradient approach employed in many previous surveys, according to data available in the literature. The main medium parameters were determined and evaluated in comparison with previous researches. The results showed in conventional pressure gradient implementation procedure, the mass conservation law is not satisfied in inertial domination regime, leading estimated values inconsistent with physical basis. Therefore, the same procedure followed, using the modified pressure gradient approached, to prevail the intrinsic limitations of conventional approach. The Beta coefficient and different types of criteria, to detect the onset of Forchheimer regime, are then identified and compared with previous similar attempts. The onset of Forchheimer regime in natural gas flow, which imposes extra pressure drop especially around the wellbore and also far from it, is quantified as the ReK values. The determined velocity values of 0.1666 and 0.105 (m/s) for sandstone and carbonate respectively, showed the point of deviation in each cases. The results demonstrated precisely estimation of flow parameters employing the modified body force approach.