Foams Stabilized by In-Situ Surface-Activated Nanoparticles in Bulk and Porous Media

Abstract

Foams for subsurface applications are traditionally stabilized by surfactants. The goal of this work is to study foam stabilization by nanoparticles-in particular, by in-situ surface-hydrophobization of hydrophilic nanoparticles. The interfacial properties of the nanoparticles were modulated by the attachment of short-chain surface modifiers (alkyl gallates) that render them partially hydrophobic, but still fully dispersible in water. First, static foams were generated with nanoparticles with varying concentrations of surface modifiers. The decay of foam height with time was measured, and half-lives were determined. Optical micrographs of foam stabilized by surface-modified nanoparticles (SMNPs) and surfactant were recorded. Second, aqueous foams were created insitu by coinjecting the SMNP solutions with nitrogen gas through a Berea sandstone core at a fixed quality. Pressure drop across the core was measured to estimate the achieved resistance factor. These pressure-drop results were then compared with those of a typical surfactant (alpha olefin sulfonate, alkyl polyglucoside) under similar conditions. Finally, oil-displacement experiments were conducted in Berea cores with surfactant and SMNP solutions as foaming agents (coinjection with nitrogen gas). A Bartsch shake test revealed the strong foaming tendency of SMNPs even with a very low initial surface-modifier concentration (0.05 wt%), whereas hydrophilic nanoparticles alone could not stabilize foam. The bubble texture of foam stabilized by SMNPs was finer than that with surfactants, indicating a stronger foam. As the degree of surface coating increased, the resistance factor of SMNP foam in a Berea core increased significantly. The corefloods in the sandstone cores with a reservoir crude oil showed that immiscible foams with SMNP solution can recover a significant amount of oil (20.6% of original oil in place) over waterfloods.

Tuning Nanoparticle Surface Chemistry and Interfacial Properties for Highly Stable Nitrogen-In-Brine Foams

“…For the NP-stabilized foam, coalescence was not observed with the microscope, as stated above (see Figure and the Supporting Video). For a sufficient surface coverage by NPs (<30 nm) between two gas films, the coalescence is suppressed by a large maximum capillary pressure P c . , The high P c can be a major advantage for foam stabilization against coalescence with NPs ,, relative to surfactants. The resistance to coalescence increases when G s ′ > G s ″ as a solid-like elastic film is less prone to rupture, as observed in Figure C.…”

Multistimuli-Responsive Foams Using an Anionic Surfactant

“…The external stimuli could be used to tune the self-assembly or aggregate structure, 37 vary the solubility, 24 trigger the crystallization of the surfactant, 38 modify foam film thickness, 22 trigger conformational changes, 30 or perform in situ surface modification. 17,39 Herein, we report a novel commercially available surfactant which exhibits a multistimuli-responsive behavior toward foam stabilization. The aforementioned second strategy was employed in this work where the foam stability was switched from a stable to an unstable state by tuning the interfacial behavior of self-assembled structures of the surfactant.…”

Fly Ash Nanoparticle-Stabilized CO2-in-Water Foams for Gas Mobility Control Applications

“…Jiang et al (2013) showed that bare silica nanoparticles, which were too hydrophilic to stabilize emulsions, could be hydrophobized in-situ by adsorption of trace amount of amidinium surfactant to stabilize octane-in-water Pickering emulsions. Recently, Singh and Mohanty (2015a) demonstrated that this concept could be applied in subsurface applications. They showed that in-situ surface-activated nanoparticles behave as surfactants and could potentially be used as foaming agents in gas enhanced oil recovery (EOR) processes.…”