Silane modification of glass and silica surfaces to obtain equally oil‐wet surfaces in glass‐covered silicon micromodel applications

Abstract

[1] Wettability is a key parameter influencing capillary pressures, permeabilities, fingering mechanisms, and saturations in multiphase flow processes within porous media. Glasscovered silicon micromodels provide precise structures in which pore-scale displacement processes can be visualized. The wettability of silicon and glass surfaces can be modified by silanization. However, similar treatments of glass and silica surfaces using the same silane do not necessarily yield the same wettability as determined by the oil-water contact angle. In this study, surface cleaning pretreatments were investigated to determine conditions that yield oil-wet surfaces on glass with similar wettability to silica surfaces treated with the same silane, and both air-water and oil-water contact angles were determined. Borosilicate glass surfaces cleaned with standard cleaning solution 1 (SC1) yield intermediate-wet surfaces when silanized with hexamethyldisilazane (HMDS), while the same cleaning and silanization yields oil-wet surfaces on silica. However, cleaning glass in boiling concentrated nitric acid creates a surface that can be silanized to obtain oil-wet surfaces using HMDS. Moreover, this method is effective on glass with prior thermal treatment at an elevated temperature of 400 C. In this way, silica and glass can be silanized to obtain equally oil-wet surfaces using HMDS. It is demonstrated that pretreatment and silanization is feasible in silicon-silica/glass micromodels previously assembled by anodic bonding, and that the change in wettability has a significant observable effect on immiscible fluid displacements in the pore network.Citation: Grate, J. W., M. G. Warner, J. W. Pittman, K. J. Dehoff, T. W. Wietsma, C. Zhang, and M. Oostrom (2013), Silane modification of glass and silica surfaces to obtain equally oil-wet surfaces in glass-covered silicon micromodel applications, Water Resour. Res., 49,[4724][4725][4726][4727][4728][4729]

Microfluidic Model Porous Media: Fabrication and Applications

“…Therefore, the resultant micromodels are best suited for performing flow experiments under harsh thermal and/or chemical conditions, such as studying two‐phase flow at reservoir conditions using crude oil . In addition, the surface wettability of glass and/or silicon can be easily modified by methods like silanization reaction, surface coating, and layer‐by‐layer electrolyte deposition . The ease of surface treatment aids in the investigation on the effect of wettability on porous media flow, which is crucial to understanding many petroleum and environmental engineering processes .…”

Lattice Boltzmann simulation of immiscible fluid displacement in porous media: Homogeneous versus heterogeneous pore network

“…These limitations can be overcome by micromodels, which are two-dimensional (2D) pore network patterns etched into materials such as silicon, glass, polyester resin, and most recently, polydimethylsiloxane (PDMS). 5 Micromodels allow for visualization of fluid distribution using cameras with or without fluorescent microscopy, and subsequent quantification of fluid saturation and interfacial area may provide mechanistic insight about physical displacement process at the microscopic level. For example, Lenormand et al 6 performed a series of classic displacement experiments for several fluid pairs in an oil-wet micromodel constructed of a polymer resin, and established a phase diagram delineating parameter domains for stable displacement, capillary, and viscous fingering.…”

Osmosis as Mechanism for Low-Salinity Enhanced Oil Recovery

“…4, where an enhanced flux, J, with increasing water-in-oil solubility, c o , is obvious. The activity of water in brine, a brine , includes nonideality [a ¼ c Á c, for example, see Kaasa (1998)], and was in this work calculated with the MultiscaleV R pressure/ volume/temperature (PVT) model (Kaasa and Østvold 2014). This model was previously (see Sandengen and Arntzen 2013) used to estimate c o in a %90 C North Sea reservoir to find relevant room-temperature model fluids, as discussed further next.…”