Wettability in complex porous materials, the mixed-wet state, and its relationship to surface roughness

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Title: Wettability in complex porous materials, the mixed-wet state, and its relationship to surface roughness
Authors: AlRatrout, A
Blunt, MJ
Bijeljic, B
Item Type: Journal Article
Abstract: A quantitative in situ characterization of the impact of surface roughness on wettability in porous media is currently lacking. We use reservoir condition micrometer-resolution X-ray tomography combined with automated methods for the measurement of contact angle, interfacial curvature, and surface roughness to examine fluid/fluid and fluid/solid interfaces inside a porous material. We study oil and water in the pore space of limestone from a giant producing oilfield, acquiring millions of measurements of curvature and contact angle on three millimeter-sized samples. We identify a distinct wetting state with a broad distribution of contact angle at the submillimeter scale with a mix of water-wet and water-repellent regions. Importantly, this state allows both fluid phases to flow simultaneously over a wide range of saturation. We establish that, in media that are largely water wet, the interfacial curvature does not depend on solid surface roughness, quantified as the local deviation from a plane. However, where there has been a significant wettability alteration, rougher surfaces are associated with lower contact angles and higher interfacial curvature. The variation of both contact angle and interfacial curvature increases with the local degree of roughness. We hypothesize that this mixed wettability may also be seen in biological systems to facilitate the simultaneous flow of water and gases; furthermore, wettability-altering agents could be used in both geological systems and material science to design a mixed-wetting state with optimal process performance.
Issue Date: 4-Sep-2018
Date of Acceptance: 17-Jul-2018
URI: http://hdl.handle.net/10044/1/61963
DOI: https://doi.org/10.1073/pnas.1803734115
ISSN: 0027-8424
Publisher: National Academy of Sciences
Start Page: 8901
End Page: 8906
Journal / Book Title: Proceedings of the National Academy of Sciences
Volume: 115
Issue: 36
Copyright Statement: © 2018 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND).
Sponsor/Funder: Abu Dhabi Company for Onshore Petroleum Operations (ADCO)
Funder's Grant Number: 16312.01
Keywords: Science & Technology
Multidisciplinary Sciences
Science & Technology - Other Topics
roughness
complex porous media
in situ reservoir conditions
contact angle
curvature
IN-SITU CHARACTERIZATION
X-RAY MICROTOMOGRAPHY
MULTIPHASE FLOW
CAPILLARY-PRESSURE
CONTACT-ANGLE
PORE
CURVATURE
MEDIA
RESERVOIRS
RECOVERY
complex porous media
contact angle
curvature
in situ reservoir conditions
roughness
complex porous media
contact angle
curvature
in situ reservoir conditions
roughness
MD Multidisciplinary
Publication Status: Published
Conference Place: United States
Online Publication Date: 2018-08-17
Appears in Collections:Faculty of Engineering
Earth Science and Engineering



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