Significance of Dynamic Effect in Capillarity during Drainage Experiments in Layered Porous Media

Abstract

We developed one‐dimensional, fully implicit numerical scheme to investigate the dynamic effect in the capillary pressure–saturation relationship used in the modeling of two‐phase flow in porous media. Its validity was investigated by means of semianalytical solutions developed by McWhorter and Sunada (1990) and the authors. The numerical scheme was used to simulate a drainage experiment where the sand and fluid properties were known. Then the numerical scheme was used to simulate a laboratory experiment in a homogeneous column, including three major models of the dynamic effect coefficient τ. This numerical scheme can handle porous medium heterogeneity and was used to simulate a fictitious experimental setup with two different sands. As a result, the penetration time of the air phase through a layered porous medium for models including dynamic effects varied between 50 and 150% compared with static models of the capillary pressure–saturation relationship. Additionally, the accumulation time of air at a material interface (i.e., the delay of the air at the interface due to the capillary barrier effect) was investigated as a function of the ratio between the air‐entry pressure values of the adjacent sands, emphasizing the differences between the dynamic and static capillary pressure models.