Characterization of the surface properties of epoxy‐type models used for multiphase flow studies in fractured media and creation of a new model

Abstract

[1] Epoxy models have been used as analogs for fractured rock surfaces in many laboratory investigations of multiphase flow processes. However, there is no agreement on how well or poorly such an analog replicates the surface chemistry of geologic materials, nor is there a satisfactory analysis of the surface properties of epoxy. This paper addresses the issue of accurately characterizing the surface chemistry of a typical epoxy used in laboratory multiphase flow studies and comparing that surface to a polystyrene surface and a radio frequency glow discharge treated polystyrene surface. Surface properties were determined using direct contact angle measurements of polar and apolar liquids on flat test samples. The epoxy was determined to have surface properties as follows: g = 62.3, g LW = 39, g AB = 23.3, g È = 0, and g É = 23.3 mJ/m 2 , where g is the total surface tension of the solid, g LW is the Lifshitz-van der Waals (LW) surface tension component, g AB is the Lewis acid base (AB) surface tension component, g É is the electron-donor (negative) parameter, and g È is the electron-acceptor (positive) parameter. Values of g É < 27.9 mJ/m 2 indicate a hydrophobic surface, which means that epoxy is not a good analog for most geologic materials. This study also explores the use of radio frequency glow discharge plasma to add hydroxyl functionality to polymer surfaces producing a material with alterable surface properties and the same optical and casting properties as epoxy. Using this method, the degree of alteration of the surface chemistry of polymer fracture models can be controlled, allowing the creation of models with a variety of different wettabilities. The resultant models were found to be durable, long lasting, and a potentially very useful alternative to the more typical epoxy models.

Correlation of Oil–Water and Air–Water Contact Angles of Diverse Silanized Surfaces and Relationship to Fluid Interfacial Tensions

“…While of considerable fundamental importance, wettability is also of practical research importance with regard to methods and devices for studying multiphase flow. The behaviors of immiscible fluids can be directly observed in experimental structures such as capillaries, Hele–Shaw cells, fracture models, thin packed beds of particles, and etched pore network micromodels. ,− The wettabilities of the surfaces in these structures are typically determined by the materials of construction, where truly clean glass and silica surfaces are water wet, while polymer resin and polydimethylsiloxane (PDMS) surfaces are oil wet. , Our current research is focused on the use of pore network micromodels to investigate immiscible fluid displacements at ambient pressures over a range of fluid viscosities and flow rates as well as high-pressure investigations with liquid and supercritical CO 2 . − The pore networks are dry-etched in silicon and oxidized to prepare a silica surface. These structures are sealed with a transparent glass cover plate by anodic bonding.…”

“…30,38−45 The wettabilities of the surfaces in these structures are typically determined by the materials of construction, where truly clean glass and silica surfaces are water wet, while polymer resin and polydimethylsiloxane (PDMS) surfaces are oil wet. 46,47 Our current research is focused on the use of pore network micromodels to investigate immiscible fluid displacements at ambient pressures over a range of fluid viscosities and flow rates as well as high-pressure investigations with liquid and supercritical CO 2 . 41−43 The pore networks are dry-etched in silicon and oxidized to prepare a silica surface.…”

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

“…Micromodels have been developed in materials such as glass, epoxy resins, silicon, and most recently, polydimethylsiloxane (PDMS). Epoxy resin [ Bergslien et al ., ; Buckley , ; Lenormand , ] and PDMS models are oil‐wet, although PDMS can be treated with plasma to create a water‐wet surface temporarily [ Berejnov et al ., ; Bhattacharya et al ., ; Javadpour and Fisher , ]. Glass micromodels, typically prepared by wet etching, are water‐wet [ Buckley , ; Conrad et al ., ; Javadpour and Fisher , ; Lenormand , ].…”

Antimicrobial assessment of phage therapy using a porcine model of biofilm infection

“…Hydrophobicity of surfaces can promote/decrease cell attachment (Katsikogianni and Missirlis, 2004). Both surfaces tested herein are hydrophobic, having similar water contact angles, with porcine skins exhibiting an angle of 91° (Elkhyat et al, 2004), and polystyrene angles between 90°and 94° (Bekele and Tsige, 2013;Bergslien et al, 2004). The use of polystyrene for biofilm growth can only be used for nonaffixing cells such as bacteria (Curtis et al, 1983;Dowling et al, 2011).…”