TY - JOUR
T1 - Micro-scale wettability of carbonate rocks via high-resolution ESEM imaging
AU - Al-Naimi, Khaloud
AU - Arif, Muhammad
AU - Aboushanab, Mahmoud
AU - Anjum, Dalaver
AU - Al Kobaisi, Mohammed
AU - Rahman, Md Motiur
AU - Mahmoud, Mohamed
AU - Iglauer, Stefan
N1 - Publisher Copyright:
© 2023 The Authors
PY - 2023/9
Y1 - 2023/9
N2 - The wettability of several materials has been traditionally quantified using macro-scale contact angles. However, precise identification of the three-phase contact (TPC) line is often difficult due to the resolution limit of macro-scale setups. Moreover, micro-level surface chemical heterogeneities can have a notable impact on the predicted wetting behavior which limits macro-scale contact angles. Thus, here, we investigate the micro-scale water wettability of condensed micro-droplets on carbonate rock surfaces via a high-resolution Environmental Scanning Electron Microscopy (ESEM). Macro- and micro-scale contact angles were evaluated under three conditions: 1) natural carbonate surfaces, 2) surfaces aged in crude oil, and 3) surfaces aged in cationic surfactant to allow for a broader insight of the impact of rock composition and surface morphology on wettability. At the macro-scale, carbonate rocks were preferentially oil-wet to intermediate-wet. However, a profound variability was observed in wetting behavior at the micro-scale where a weakly water-wet state (50° ≥ θ ≥ 80°) was prevalent with evidence of minor oil-wet patches too. At the micro-scale, for the 100% dolomite sample, the contact angle (θ) varied from ∼66° to 76° under natural conditions, while the same sample aged in crude oil depicted a remarkable variability, i.e., θ ranged from 58° to 132° with the majority of micro-droplets having θ of ∼85° – thus suggesting a mixed-wet behavior. For the same sample aged in surfactant, θ was <5° at micro and macro-scales, with few micro-droplets having θ of ∼89°. However, the macro-scale θ values were 105° (natural) and 90° (oil-aged) – suggesting notable variability at macro- and micro-scales. These findings reflect: a) significant differences among macro- and micro-scale contact angles, and b) surface wetting at the micro-scale captures physical and chemical properties of the rock, i.e., surface roughness, pore size and distribution, and chemical composition. The study herein presents qualitative and semi-quantitative analyses of the non-uniform wetting behavior of carbonate rocks and the associated rock/fluid interactions through a multi-scale perspective and thus have broader implications for flow in porous medium.
AB - The wettability of several materials has been traditionally quantified using macro-scale contact angles. However, precise identification of the three-phase contact (TPC) line is often difficult due to the resolution limit of macro-scale setups. Moreover, micro-level surface chemical heterogeneities can have a notable impact on the predicted wetting behavior which limits macro-scale contact angles. Thus, here, we investigate the micro-scale water wettability of condensed micro-droplets on carbonate rock surfaces via a high-resolution Environmental Scanning Electron Microscopy (ESEM). Macro- and micro-scale contact angles were evaluated under three conditions: 1) natural carbonate surfaces, 2) surfaces aged in crude oil, and 3) surfaces aged in cationic surfactant to allow for a broader insight of the impact of rock composition and surface morphology on wettability. At the macro-scale, carbonate rocks were preferentially oil-wet to intermediate-wet. However, a profound variability was observed in wetting behavior at the micro-scale where a weakly water-wet state (50° ≥ θ ≥ 80°) was prevalent with evidence of minor oil-wet patches too. At the micro-scale, for the 100% dolomite sample, the contact angle (θ) varied from ∼66° to 76° under natural conditions, while the same sample aged in crude oil depicted a remarkable variability, i.e., θ ranged from 58° to 132° with the majority of micro-droplets having θ of ∼85° – thus suggesting a mixed-wet behavior. For the same sample aged in surfactant, θ was <5° at micro and macro-scales, with few micro-droplets having θ of ∼89°. However, the macro-scale θ values were 105° (natural) and 90° (oil-aged) – suggesting notable variability at macro- and micro-scales. These findings reflect: a) significant differences among macro- and micro-scale contact angles, and b) surface wetting at the micro-scale captures physical and chemical properties of the rock, i.e., surface roughness, pore size and distribution, and chemical composition. The study herein presents qualitative and semi-quantitative analyses of the non-uniform wetting behavior of carbonate rocks and the associated rock/fluid interactions through a multi-scale perspective and thus have broader implications for flow in porous medium.
KW - Contact angle
KW - Imaging
KW - Micro-scale
KW - Rock surfaces
KW - Wettability
UR - http://www.scopus.com/inward/record.url?scp=85168816325&partnerID=8YFLogxK
U2 - 10.1016/j.rinp.2023.106871
DO - 10.1016/j.rinp.2023.106871
M3 - Article
AN - SCOPUS:85168816325
SN - 2211-3797
VL - 52
JO - Results in Physics
JF - Results in Physics
M1 - 106871
ER -