Effects of Pore-Scale Geometry and Wettability on Two-Phase Relative Permeabilities within Elementary Cells

Abstract

Abstract:We study the relative role of the complex pore space geometry and wettability of the solid matrix on the quantification of relative permeabilities of elementary cells of porous media. These constitute a key element upon which upscaling frameworks are typically grounded. In our study we focus on state immiscible two-phase flow taking place at the scale of elementary cells. Pressure-driven two-phase flow following simultaneous co-current injection of water and oil is numerically solved for a suite of regular and stochastically generated two-dimensional explicit elementary cells with fixed porosity and sharing main topological/morphological features. We show that the relative permeabilities of the randomly generated elementary cells are significantly influenced by the formation of preferential percolation paths, called principal pathways, giving rise to a strongly nonuniform distribution of fluid fluxes. These pathways are a result of the spatially variable resistance that the random pore structures exert on the fluid. The overall effect on relative permeabilities of the diverse organization of principal pathways, as driven by a given random realization at the scale of the elementary cell, is significantly larger than that of the wettability of the host rock. In contrast to what can be observed for the random cells analyzed, the relative permeabilities of regular cells display a clear trend with contact angle at the investigated scale.

Effect of Rock Dissolution on Two-Phase Relative Permeabilities: Pore-Scale Simulations Based on Experimental Data

“…Furthermore, studies on the effects of acid injection on the structure and properties of porous materials, as well as on the relationship between permeability and pore size, highlight the importance of considering the pore structure when analyzing fluid flow in a porous media [18,19]. This is also supported by research demonstrating the influence of pore geometric parameters on fluid flow processes [20,21].…”

Influence of the fluid–fluid drag on the pressure drop in simulations of two-phase flows through porous flow cells

“…given fluid pair only depends on the saturation (Brooks and Corey, 1964;Van Genuchten, 1980), even though the relative permeabilities may also depend on the capillary number (Li et al, 2005), the flow regime (Avraam and Payatakes, 1995;Bianchi Janetti et al, 2017), the viscosity ratio (Yuster et al, 1951;Ehrlich, 1993;Yiotis et al, 2007) and other properties such as wettability (Morrow et al, 1973;Anderson et al, 1987;Li et al, 2005). Since the early 1980s, much work has aimed at improving the generalized Darcy equations on a sound physical basis.…”

Effect of surface wettability of ceramic proppant on oil flow performance in hydraulic fractures

“…[26][27][28][29] Designed for eliminating the capillary pressure, the neutrally wet surface has no preferential affinity for both the aqueous phase and hydrogen, simultaneously being hydrophobic and lipophobic. 33,39,40 Nevertheless, those findings failed to explain the oil-increasing flow within the mixed-wet proppants pack. 26,30 Compared with mixed-wet proppants, in this research, the oil-wet proppants resulted in higher water productivity.…”

“…Compared with pore geometry, the effect of surface wettability of ceramic proppants on the fluid flow performance can be diminished, especially in a porous medium with a high permeability and a large amount of micro fluid channels. 33,39,40 Nevertheless, those findings failed to explain the oil-increasing flow within the mixed-wet proppants pack. Since the mixed-wet proppants simultaneously had preferential affinities for oil and water, they should lead to low water recovery and low oil recovery.…”