Experimental measurement of dynamic effect in capillary pressure relationship for two‐phase flow in weakly layered porous media

Well‐defined laboratory experiments have been conducted to determine the significance of dynamic effect in capillary pressure relationships for two‐phase flow in weakly heterogeneous (layered) porous media. The heterogeneous layers are composed of a fine sand layer sandwiched between two coarse sand layers. Dynamic and quasi‐static capillary pressure–saturation ( P c – S ) and ∂ S /∂t–t relationships are determined, which are then used to determine the dynamic effect, indicated by a dynamic coefficient (τ). As well known, τ establishes the speed at which flow equilibrium (∂ S /∂ t = 0) is reached. In consistent with previous studies, τ is found to be a nonlinear function of saturation that depends on the medium permeability and the intensity of heterogeneity. τ values increase in the regions of less permeability (fine sand) in the domain. However, the τ– S functional dependence follows similar trends at different locations within the domain including regions of different permeability. We argue that saturation weighted average of local τ– S curves can be used as an effective τ– S curve for the whole domain which, when done, follows an exponential trend too. The effective τ– S curves suggest that the effective τ values for the porous layers lie between the τ values of coarse and fine sands at the same water saturation, and it is dominated by the τ values of coarse sand as it occupied the maximum volume of the domain. © 2012 The Authors. AIChE Journal, published by Wiley on behalf of the AIChE. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. AIChE J, 59: 1723–1734, 2013