Experiments and analysis of drainage displacement processes relevant to carbon dioxide injection

Abstract

The motivation for this work is a dramatically improved understanding of the fluid mechanics of drainage processes with applications such as CO_{2} storage in saline aquifers and water-alternating-gas injection as an enhanced oil recovery method. In this paper we present in situ distributions of wetting and nonwetting fluids obtained during core-scale two-phase immiscible drainage experiments. The ratio of the viscosity of the resident fluid to that of the invading fluid varies across a range of 0.43 to 150. Saturation distributions observed during dynamic displacement experiments are surprisingly smooth and do not display only one or a few dominant fingers, contrary to the indications of the current literature. The analysis of the saturation distribution using the fractal dimensions of the dynamic three-dimensional saturation distributions suggests that the constitutive relationships for porous media, namely, the relative permeability functions, are history dependent. Accordingly, it is suggested that the nonlinear, unstable flow regime is the regime where efforts to improve physical understanding must be focused.

Pore-scale visualization and characterization of viscous dissipation in porous media

“…We also use dimensionless numbers to characterize the macroscale parameters and identify different flow regimes. The viscosity ratio between oil (o) and water (w), M, is defined as, (9) and the capillary number, Ca, that determines the importance of surface tension forces with respect to viscous forces, is calculated as (10) where is the velocity of the oil/water interface at the center of the inlet channel and is the oil/water interfacial tension.…”

“…Despite a very large usage in the subsurface engineering community, a number of studies have emphasized the limits of this model [7][8][9]. For example, investigations of unstable two-phase flow at the core-scale [10] have demonstrated that the flow processes are not described adequately by the generalized Darcy's law. This is not surprising given that this model relies upon strong assumptions, including a locally stable fluid-fluid interface at the pore-scale [11], as well as separation of scale between the local events and the large-scale phenomena.…”

A microfluidic study of transient flow states in permeable media using fluorescent particle image velocimetry

“…Models for macro-scale permeable media often rely on some form of Darcy's law as the conservation of momentum (Aryana and Kovscek, 2012). Darcy's law provides a linear relation between the gradient of the field potential (e.g., hydraulic head or pressure) and the macroscale (Darcy) velocity (Whitaker, 1986).…”

History independence of steady state in simultaneous two-phase flow through two-dimensional porous media

“…In that context, it is crucial to determine whether the steady state is independent on the history of the process, or in other words, whether it is a real state in a thermodynamic sense [33]. It is well known that when drainage and imbibition occur successively, the relative permeabilities become history dependent and the pressure-saturation curves display an hysteresis [34,35], the underlying pore-scale mechanisms of which are known. Besides in the well-known magnetic and elastic systems, such history dependence and hysteresis has also been observed in different flow processes like hydrodynamic heat flow [36] and particle flow through random media [37].…”