More Like this

1. Polyelectrolyte Complex Stabilized CO2 Foam Systems for Hydraulic Fracturing Application

   https://doi.org/10.2118/187489-MS  

   Anandan, Rudhra ; Johnson, Stephen ; Barati, Reza ( September 2017 , SPE Liquids-Rich Basins Conference- North America)

   Hydraulic fracturing of oil and gas wells is a water intensive process. Limited availability, cost and increasing government regulations restraining the use and disposal of fresh water have led to the need for alternative fracturing fluids. Using CO2 foam as a fracturing fluid can drastically reduce the need for water in hydraulic fracturing. We address the addition of polyelectrolyte complex nanoparticles (PECNP) to surfactant solutions to improve foam stability, durability and rheological properties at high foam qualities. Polyelectrolyte pH and polyanion/polycation ratios were varied to minimize particle size and maximize absolute zeta potential of the resulting nanoparticles. Rheological tests were conducted on foam systems of varying surfactant/PECNP ratios and different foam quality to understand the effect of shear on viscosity under simulated reservoir conditions of 40°C and 1300 psi. The same foam systems were tested for stability and durability in a view cell at reservoir conditions. Supercritical CO2 foam generated by surfactant alone resulted in short lived, low viscosity foam because of surfactant drainage from foam lamellae. However, addition of PECNP strengthens the foam film by swelling the film due to increased osmotic pressure and electrostatic forces. Electrostatic interactions reduce dynamic movement of surfactant micelles, thereby stabilizing the foam lamellae, which imparts high durability and viscosity to supercritical CO2 foams. From the rheology test results, it was concluded that increasing foam quality and the presence of PECNP resulted in improved viscosity. Also, foam systems with PECNP showed promising results compared with foam generated using surfactant alone in the view cell durability test. The addition of optimized polyelectrolyte nanoparticles to the surfactant can improve viscosity and durability of supercritical CO2 foam during hydraulic fracturing, which can lead to large reductions in water requirements.

    

   more » « less
2. PDMS polymerized high internal phase emulsions (polyHIPEs) with closed-cell, aqueous-filled microcavities

   https://doi.org/10.1039/c9sm01732a  

   Kataruka, Amrita ; Hutchens, Shelby B. ( December 2019 , Soft Matter)

   Emulsion templates can produce a wide range of unique microstructures via solidification of the continuous phase. Some of these structures result in unique, fluid-filled composites reminiscent of biological tissue when the templating droplets develop into closed-cell structures. However, the state-of-the-art falls short in replicating the mechanical and functional response of biological structures due to stiff, fragile, and bio-incompatible materials while lacking systematic processing parameters. This article describes the synthesis of high internal phase, closed-cell, polydimethylsiloxane (PDMS) elastomeric foams which simultaneously achieve biocompatibility, mechanical robustness, flexibility, and selective permeability. Water-in-oil high internal phase emulsions (HIPEs) stabilized by silica nano-particles (SNPs) provide the microstructural template, resulting in a >74% by volume aqueous phase (up to 82%). To overcome the prohibitive barrier to HIPE formation when using a mechanically-superior, but highly viscous commercial PDMS kit, we produce HIPE templates via centrifugation of low internal phase emulsions (LIPEs, <30% by volume dispersed phase). This oil phase crosslinks into an aqueous-filled (water + glycerol + NaCl) elastomeric composite. The composite's microstructural dependence on viscosity ratio, mixing speed, emulsifier concentration, and centrifugal force are systematically characterized. The resulting microstructured, fluid-filled elastomer composites exhibit mechanically robust and highly flexible behavior due to the excellent properties of the PDMS continuous phase. 

   more » « less
3. Drainage via stratification and nanoscopic thickness transitions of aqueous sodium naphthenate foam films

   https://doi.org/10.1039/D1SM01169C  

   Ochoa, Chrystian ; Xu, Chenxian ; Martínez Narváez, Carina D. ; Yang, William ; Zhang, Yiran ; Sharma, Vivek ( October 2021 , Soft Matter)

   Sodium naphthenates (NaNs), found in crude oils and oil sands process-affected water (OSPW), can act as surfactants and stabilize undesirable foams and emulsions. Despite the critical impact of soap-like NaNs on the formation, properties, and stability of petroleum and OSPW foams, there is a significant lack of studies that characterize foam film drainage, motivating this study. Here, we contrast the drainage of aqueous foam films formulated with NaN with foams containing sodium dodecyl sulfate (SDS), a well-studied surfactant system, in the relatively low concentration regime ( c /CMC < 12.5). The foam films exhibit drainage via stratification, displaying step-wise thinning and coexisting thick–thin regions manifested as distinct shades of gray in reflected light microscopy due to thickness-dependent interference intensity. Using IDIOM (interferometry digital imaging optical microscopy) protocols that we developed, we analyze pixel-wise intensity to obtain thickness maps with high spatiotemporal resolution (thickness <1 nm, lateral ∼500 nm, time ∼10 ms). The analysis of interference intensity variations over time reveals that the aqueous foam films of both SDS and NaN possess an evolving, dynamic, and rich nanoscopic topography. The nanoscopic thickness transitions for stratifying SDS foam films are attributed to the role played by damped supramolecular oscillatory structural disjoining pressure contributed by the confinement-induced layering of spherical micelles. In comparison with SDS, we find smaller concentration-dependent step size and terminal film thickness values for NaN, implying weaker intermicellar interactions and oscillatory structural disjoining pressure with shorter decay length and periodicity. 

   more » « less
4. Particle Size and Rheology of Silica Particle Networks at the Air–Water Interface

   https://doi.org/10.3390/nano13142114  

   Thakur, Siddharth ; Razavi, Sepideh ( July 2023 , Nanomaterials)

   Silica nanoparticles find utility in different roles within the commercial domain. They are either employed in bulk within pharmaceutical formulations or at interfaces in anti-coalescing agents. Thus, studying the particle attributes contributing to the characteristics of silica particle-laden interfaces is of interest. The present work highlights the impact of particle size (i.e., 250 nm vs. 1000 nm) on the rheological properties of interfacial networks formed by hydrophobically modified silica nanoparticles at the air–water interface. The particle surface properties were examined using mobility measurements, Langmuir trough studies, and interfacial rheology techniques. Optical microscopy imaging along with Langmuir trough studies revealed the microstructure associated with various surface pressures and corresponding surface coverages (ϕ). The 1000 nm silica particle networks gave rise to a higher surface pressure at the same coverage compared to 250 nm particles on account of the stronger attractive capillary interactions. Interfacial rheological characterization revealed that networks with 1000 nm particles possess higher surface modulus and yield stress in comparison to the network obtained with 250 nm particles at the same surface pressure. These findings highlight the effect of particle size on the rheological characteristics of particle-laden interfaces, which is of importance in determining the stability and flow response of formulations comprising particle-stabilized emulsions and foams. 

   more » « less
5. Rheology of three-phase suspensions determined via dam-break experiments

   https://doi.org/10.1098/rspa.2021.0394  

   Birnbaum, Janine ; Lev, Einat ; Llewellin, Edward W. ( October 2021 , Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences)

   Three-phase suspensions, of liquid that suspends dispersed solid particles and gas bubbles, are common in both natural and industrial settings. Their rheology is poorly constrained, particularly for high total suspended fractions (≳0.5). We use a dam-break consistometer to characterize the rheology of suspensions of (Newtonian) corn syrup, plastic particles and CO 2 bubbles. The study is motivated by a desire to understand the rheology of magma and lava. Our experiments are scaled to the volcanic system: they are conducted in the non-Brownian, non-inertial regime; bubble capillary number is varied across unity; and bubble and particle fractions are 0 ≤  ϕ gas  ≤ 0.82 and 0 ≤  ϕ solid  ≤ 0.37, respectively. We measure flow-front velocity and invert for a Herschel–Bulkley rheology model as a function of ϕ gas , ϕ solid , and the capillary number. We find a stronger increase in relative viscosity with increasing ϕ gas in the low to intermediate capillary number regime than predicted by existing theory, and find both shear-thinning and shear-thickening effects, depending on the capillary number. We apply our model to the existing community code for lava flow emplacement, PyFLOWGO, and predict increased viscosity and decreased velocity compared with current rheological models, suggesting existing models may not adequately account for the role of bubbles in stiffening lavas. 

   more » « less