Effect of Pore-Scale Heterogeneity and Capillary-Viscous Fingering on Commingled Waterflood Oil Recovery in Stratified Porous Media

Abstract

Oil recovery prediction and field pilot implements require basic understanding and estimation of displacement efficiency. Corefloods and glass micromodels are two of the commonly used experimental methods to achieve this. In this paper, waterflood recovery is investigated using layered etched glass micromodel and Berea sandstone core plugs with large permeability contrasts. This study focuses mainly on the effect of permeability (heterogeneity) in stratified porous media with no cross-flow. Three experimental setups were designed to represent uniformly stratified oil reservoir with vertical discontinuity in permeability. Waterflood recovery to residual oil saturation (Sor) is measured through glass micromodel (to aid visual observation), linear coreflood, and forced drainage-imbibition processes by ultracentrifuge. Six oil samples of low-to-medium viscosity and porous media of widely different permeability (darcy and millidarcy ranges) were chosen for the study. The results showed that waterflood displacement efficiencies are consistent in both permeability ranges, namely, glass micromodel and Berea sandstone core plugs. Interestingly, the experimental results show that the low permeability zones resulted in higher ultimate oil recovery compared to high permeability zones. At Sor microheterogeneity and fingering are attributed for this phenomenon. In light of the findings, conformance control is discussed for better sweep efficiency. This paper may be of help to field operators to gain more insight into microheterogeneity and fingering phenomena and their impact on waterflood recovery estimation.

Molecular Dynamic Simulation of Crude Oil (SARA) Water Flooding Mechanisms under Different Driving Forces in Oleophilic Pore Channels

“…The residual oil saturation in oleophilic sandstones was determined, and the size distribution of the residual oil clusters was analyzed using X-ray microstratigraphy by Iglauer et al [8]. Al-Shalabi et al [9] investigated the effect of permeability differences on remaining oil saturation in stratified porous media without cross-flow using a stratified etched glass micromodel and a Berea sandstone core with large permeability differences for water flooding experiments. Iyi et al [10] in 2021 analyzed the effect of different wettability walls on the oil recovery efficiency of water drive by Ansys-Fluent software and concluded that low IFT is sufficient to resist the capillary effect, but the oil adhesion to the wall due to the wettability effect cannot improve the recovery.…”

Insights into the Effects of Pore Size Distribution on the Flowing Behavior of Carbonate Rocks: Linking a Nano-Based Enhanced Oil Recovery Method to Rock Typing

“…Residual oil remains in the reservoirs after conventional water flooding is often regarded as the target for enhanced oil recovery (EOR) processes. A comprehensive understanding and evaluation of the displacement efficiency represent a fundamental requirement for oil production forecast and field development planning [ 1 , 2 , 3 ]. At a laboratory scale, similar rock types have different residual oil saturations after water flooding, and a particular relation between the macroscopic characteristics and the flow behavior of the porous medium is yet to be developed [ 4 , 5 ].…”

“…Hence, it is essential to study the effect of PSD on the flow behavior of the reservoir rock to understand the governing mechanisms of the fluid flow through the porous medium. Al-Shalabi and Ghosh studied the effect of permeability contrast on the efficiency of water flooding in different porous media consisting of a glass micromodel (representing a high-permeability medium) and a set of sandstone core samples (representing a low- to medium-permeability medium) [ 1 ]. They employed three techniques to measure the water displacement efficiency, namely linear core flooding, micro model flooding, and imbibition by ultracentrifugation.…”

Pore-scale numerical simulation of supercritical CO2 migration in porous and fractured media saturated with water

“…The scCO 2 migration and storage in the natural sandstone or glass beads at the core scale, either homogeneous or heterogeneous, during the drainage process of the core flooding experiments are widely studied using many physical experimental tools: (1) the traditional optical technique by examining thin-sections in transmitted and reflected light or microscopic simulation model (e.g., a pore-scale network model, rock etching model) (Mattax, 1961;Jamaloei et al, 2010;Al-Shalabi and Ghosh, 2016); (2) scanning electron microscopy to observe the wettability of scCO 2 film on the surface of mineral grains, while considering the impacts of composition, size and distribution on micro-scale fluid flow (Combes et al, 1998;Kareem, 2015); (3) confocal laser scanning microscopy; (4) the greatly developed computed tomography (CT) technology, which can realize the three-dimensional (3D) visualization with a high resolution (several µm) and has already been widely used in investigating the distribution of residual oil (Turner et al, 2004;Youssef et al, 2010;Iglauer et al, 2012) or scCO 2 (Perrin and Benson, 2010;Krevor et al, 2012;Wang et al, 2013;Wei et al, 2014;Zhang et al, 2014;Miao et al, 2019;Xu et al, 2020); and (5) nuclear magnetic resonance imaging that is also widely used in studying fluid distribution in porous or fractured media at mm or µm resolution (Baldwin and Yamanashi, 1989;Suekane et al, 2009;Song et al, 2012;Yu et al, 2014;Prather, 2015).…”