Probing Effective Wetting in Subsurface Systems

Sun, Chenhao; McClure, James E.; Mostaghimi, Peyman; Herring, Anna L.; Berg, Steffen; Armstrong, Ryan T.

doi:10.1029/2019gl086151

Cited by 47 publications

(42 citation statements)

References 39 publications

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“…Clearly, other simple periodic geometries [102] might be used instead of the one proposed here with similar success. In any case, the proposed model can then be exploited for systematic sensitivity analysis, employed for further upscaling [103] or to provide for an in silico platform for testing advanced theories of wetting [64,104]. More importantly, it can be employed as a test system to understand outstanding inconsistencies between theories and simulations (and even resolving contradictions amongst simulations results), as pointed out by Svoboda et al [105].…”

Section: Discussionmentioning

confidence: 99%

Surrogate Models for Studying the Wettability of Nanoscale Natural Rough Surfaces Using Molecular Dynamics

et al. 2020

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A molecular modeling methodology is presented to analyze the wetting behavior of natural surfaces exhibiting roughness at the nanoscale. Using atomic force microscopy, the surface topology of a Ketton carbonate is measured with a nanometer resolution, and a mapped model is constructed with the aid of coarse-grained beads. A surrogate model is presented in which surfaces are represented by two-dimensional sinusoidal functions defined by both an amplitude and a wavelength. The wetting of the reconstructed surface by a fluid, obtained through equilibrium molecular dynamics simulations, is compared to that observed by the different realizations of the surrogate model. A least-squares fitting method is implemented to identify the apparent static contact angle, and the droplet curvature, relative to the effective plane of the solid surface. The apparent contact angle and curvature of the droplet are then used as wetting metrics. The nanoscale contact angle is seen to vary significantly with the surface roughness. In the particular case studied, a variation of over 65° is observed between the contact angle on a flat surface and on a highly spiked (Cassie–Baxter) limit. This work proposes a strategy for systematically studying the influence of nanoscale topography and, eventually, chemical heterogeneity on the wettability of surfaces.

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Section: Discussionmentioning

confidence: 99%

Surrogate Models for Studying the Wettability of Nanoscale Natural Rough Surfaces Using Molecular Dynamics

et al. 2020

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“…This was done to avoid the bias of the in situ contact angle measurements in a single plane, which are generally measured in the plane perpendicular to the direction of displacing fluid flow, as seen in the works of Kishvand et al (2016) and Kuang et al (2020) [33][34][35]51,52]. This procedure, which is manual, tried to ensure that the topological principles could be preserved as suggested by [6,53] (which is also subject to oversmoothing using several filters). The error of measurements due to pixelization-related errors cannot be avoided in any of the procedures but can be limited by repeat measurements for each visible three-phase contact line, and we tried to keep the absolute error within 3 • , which is insignificant for such measurements.…”

Section: Resultsmentioning

confidence: 99%

In Situ Wettability Investigation of Aging of Sandstone Surface in Alkane via X-ray Microtomography

et al. 2020

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Wettability of surfaces remains of paramount importance for understanding various natural and artificial colloidal and interfacial phenomena at various length and time scales. One of the problems discussed in this work is the wettability alteration of a three-phase system comprising high salinity brine as the aqueous phase, Doddington sandstone as porous rock, and decane as the nonaqueous phase liquid. The study utilizes the technique of in situ contact angle measurements of the several 2D projections of the identified 3D oil phase droplets from the 3D images of the saturated sandstone miniature core plugs obtained by X-ray microcomputed tomography (micro-CT). Earlier works that utilize in situ contact angles measurements were carried out for a single plane. The saturated rock samples were scanned at initial saturation conditions and after aging for 21 days. This study at ambient conditions reveals that it is possible to change the initially intermediate water-wet conditions of the sandstone rock surface to a weakly water wetting state on aging by alkanes using induced polarization at the interface. The study adds to the understanding of initial wettability conditions as well as the oil migration process of the paraffinic oil-bearing sandstone reservoirs. Further, it complements the knowledge of the wettability alteration of the rock surface due to chemisorption, usually done by nonrepresentative technique of silanization of rock surface in experimental investigations.

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“…If the free energy associated with the solid-fluid and fluid-fluid interfaces depend only on interface areas, the contact angle will depend on the interfacial tensions between the two fluids ( 21 ) and fluids with solid ( 2s , 1s ) through Young's equation 1, (Young (1805) and Laplace (1806)) The applicability of Eq. (1) is restricted to ideal smooth surfaces of a homogeneous solid material, and the corresponding contact angle is sometimes referred to as an intrinsic contact angle (Sun et al 2020a). The effect of rough surfaces can be included in the surface tensions 1s and 2s , with a resulting effective contact angle .…”

Section: Motivationmentioning

confidence: 99%

“…Sun et al (2020b) introduced this approach by linking local curvatures and topology of a cluster using the Gauss-Bonnet theorem. Blunt et al (2020) and Sun et al (2020a, c) elaborated on the methodology. These methods often require calculation of local curvatures which are typically products of surface smoothing, a common part shared between the direct measurement and the integral geometry methods.…”

Section: Motivationmentioning

confidence: 99%

Contact Angles in Two-Phase Flow Images

2020

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In this work, we calculate contact angles in X-ray tomography images of two-phase flow in order to investigate the wettability. Triangulated surfaces, generated using the images, are smoothed to calculate the contact angles. As expected, the angles have a spread rather than being a constant value. We attempt to shed light on sources of the spread by addressing the overlooked mesh corrections prior to smoothing, poorly resolved image features, cluster-based analysis, and local variations of contact angles. We verify the smoothing algorithm by analytical examples with known contact angle and curvature. According to the analytical cases, point-wise and average contact angles, average mean curvature and surface area converge to the analytical values with increased voxel grid resolution. Analytical examples show that these parameters can reliably be calculated for fluid–fluid surfaces composed of roughly 3000 vertices or more equivalent to 1000 pixel2. In an experimental image, by looking into individual interfaces and clusters, we show that contact angles are underestimated for wetting fluid clusters where the fluid–fluid surface is resolved with less than roughly 500 vertices. However, for the fluid–fluid surfaces with at least a few thousand vertices, the mean and standard deviation of angles converge to similar values. Further investigation of local variations of angles along three-phase lines for large clusters revealed that a source of angle variations is anomalies in the solid surface. However, in the places least influenced by such noise, we observed that angles tend to be larger when the line is convex and smaller when the line is concave. We believe this pattern may indicate the significance of line energy in the free energy of the two-phase flow systems.

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Probing Effective Wetting in Subsurface Systems

Cited by 47 publications

References 39 publications

Surrogate Models for Studying the Wettability of Nanoscale Natural Rough Surfaces Using Molecular Dynamics

Surrogate Models for Studying the Wettability of Nanoscale Natural Rough Surfaces Using Molecular Dynamics

In Situ Wettability Investigation of Aging of Sandstone Surface in Alkane via X-ray Microtomography

Contact Angles in Two-Phase Flow Images

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