Wettability Effects on Capillary Pressure, Relative Permeability, and Irredcucible Saturation Using Porous Plate

Abstract

An understanding of the mechanisms by which oil is displaced from porous media requires the knowledge of the role of wettability and capillary forces in the displacement process. The determination of representative capillary pressure ( ) data and wettability index of a reservoir rock is needed for the prediction of the fluids distribution in the reservoir: the initial water saturation and the volume of reserves. This study shows how wettability alteration of an initially water-wet reservoir rock to oil-wet affects the properties that govern multiphase flow in porous media, that is, capillary pressure, relative permeability, and irreducible saturation. Initial water-wet reservoir core samples with porosities ranging from 23 to 33%, absolute air permeability of 50 to 233 md, and initial brine saturation of 63 to 87% were first tested as water-wet samples under air-brine system. This yielded irreducible wetting phase saturation of 19 to 21%. The samples were later tested after modifying their wettability to oil-wet using a surfactant obtained from glycerophtalic paint; and the results yielded irreducible wetting phase saturation of 25 to 34%. From the results of these experiments, changing the wettability of the samples to oil-wet improved the recovery of the wetting phase.

Upscaling of Dynamic Capillary Pressure of Two‐Phase Flow in Sandstone

“…During displacement, the governing equations that describe the mass balance and macro DCP have been given as (Dahle et al, ; Tang et al, ; Yu et al, ) where is the Darcy velocity vector of phase α (the arrow above a variable denotes a vector hereinafter, and since we focus on two‐phase flow in this study, α is either “ n ” for nonwetting phase or “ w ” for wetting phase.) η α is the viscosity of phase α, ϕ is the porosity, k s is the absolute permeability, and ρ α and K ra are the corresponding density and the relative permeability (Blunt et al, ; Falode & Manuel, ), respectively, S α is the saturation and bounded with a constraint of S w + S n = 1, and P n and P w are the macro pressures of the nonwetting and wetting phases, respectively. denotes DCP, which is also critical to analyze the phase behavior in equations –.…”

The influence of wettability on the petrophysical parameters of reservoir rocks

“…Capillary pressure curves directly determine irreducible water saturation, residual oil saturation, and rock wettability and can be used to determine the water oil contact point and approximate oil recovery. Water flood performance is also significantly affected by the capillary pressure of the rock [13].…”

“…Research on the influence of wettability on relative permeability has been conducted by a number of authors [2,3,9,10,13,14,15,17,32].…”

“…Wettability refers to the tendency of one fluid to spread on or adhere to a solid surface in the presence of immiscible fluids. In natural porous media, the wettability varies from point to point depending on surface roughness, immobile adsorbed liquid layers, and the adsorptive properties of the mineral constituents [13]. Anderson reported that coal, graphite, sulfur, talc, talc-like silicates, and many sulfides are probably neutrally wet to oil-wet [5].…”

“…Anderson reported that coal, graphite, sulfur, talc, talc-like silicates, and many sulfides are probably neutrally wet to oil-wet [5]. On the other hand, most common minerals such as quartz, carbonates, and sulfates are strongly water wet [13].…”