Andrew Jay Worthen

Exponent, Inc. · Polymer Science and Materials Chemistry

Chitosan beads attract interest in diverse applications, including drug delivery, biocatalysis and water treatment. They can be formed through several supramolecular pathways, ranging from phase inversion in alkaline solutions, to the ionic crosslinking of chitosan with multivalent anions, to polyelectrolyte or surfactant/polyelectrolyte complexati...

Whereas many studies have examined stabilization of emulsions and foams in low salinity aqueous phases with nanoparticles (NPs) with and without added surfactants, interest has grown recently in much higher salinities relevant to subsurface oil and gas applications. It is shown for the first time that NPs grafted with well-defined low molecular wei...

Foam application in subsurface processes including environmental remediation, geological carbon-sequestration, and gas-injection enhanced oil recovery (EOR) has the potential to enhance contamination remediation, secure \(\hbox {CO}_{2}\) storage, and improve oil recovery, respectively. Nanoparticles are a promising alternative to surfactants in cr...

The design of surfactants for stabilizing CO2-in-water (brine) (C/W) foams at high temperature is challenging given the low density (solvent strength) of CO2, limited surfactant solubility in brine, and a lack of knowledge of the interfacial and rheological properties. Herein, the tail length of trimethylammonium cationic surfactants was optimized...

CO2/water foams are of interest for mobility control in CO2 EOR and as energized fracture fluids, or hybrid processes that combine aspects of both processes. In fracturing applications, it would be desirable to lower the water level as much as possible to minimize the production of wastewater and formation damage. It is challenging to stabilize ult...

The use of foam in gas enhanced oil recovery (EOR) processes has the potential to improve oil recovery by reducing gas mobility. Nanoparticles are a promising alternative to surfactants in creating foam in the harsh environments found in many oil fields. We conducted several CO2-in-brine foam generation experiments in Boise sandstones with surface-...

The immense nanotechnology advances in other industries provided opportunities to rapidly develop various applications of nanoparticles in the oil and gas industry. In particular, nanoparticle has shown its capability to improve the emulsion stability by generating so-called Pickering emulsion, which is expected to improve EOR processes with better...

Nanoparticle (NP)-stabilized foams can be generated at extreme water-deficient conditions (with quality as high as 95–99%) and yet with apparent viscosities >100 cP. This makes them greatly appealing for hydraulic fracturing applications, where minimal water consumption and leak-off to the reservoir are desired. Initial assessment of propensities o...

Nanoparticles are a promising alternative to surfactants to stabilize emulsions or foams in enhanced oil recovery (EOR) processes due to their effectiveness in very harsh environments found in many of the oilfields around the world. While the size-dependent properties of nanoparticles have been extensively studied in the area of optics or cellular...

The interfacial properties for surfactants at the supercritical CO2-water (C-W) interface at temperatures above 80 °C have very rarely been reported given limitations in surfactant solubility and chemical stability. These limitations, along with the weak solvent strength of CO2, make it challenging to design surfactants that adsorb at the C-W inter...

Whereas numerous studies of stabilization of nanoparticles (NPs) in electrolytes have examined biological fluids, the interest has grown recently in media with much higher ionic strengths including seawater and brines relevant to environmental science and subsurface oil and gas reservoirs. Given that electrostatic repulsion is limited at extremely...

For foams with ultra low water contents, the capillary pressure is very large and induces rapid drainage that destabilizes the aqueous lamellae between the gas bubbles. However, we show that high pressure CO2-in-water foams can be stabilized with a viscoelastic aqueous phase composed of entangled wormlike micelles, even for extremely high CO2 volum...

Foam is injected in the subsurface to improve mobility control through the increase in the effective gas viscosity, e.g., in CO(Formula presented.)-based enhanced oil recovery processes. As fine-textured foam has higher viscosity, it is envisaged to achieve an optimal foam texture and to maintain it for the entire period of an application. However,...

To date, relatively few examples of ultra-high internal phase supercritical CO2-in-water foams (also referred to as macroemulsions) have been observed, despite interest in applications including "waterless" hydraulic fracturing in energy production. The viscosities and stabilities of foams up to 0.98 CO2 volume fraction were investigated in terms o...

Although EOR with CO2 is practiced domestically on large scale, the potential for advancement is enormous. The ongoing search for better solutions has motivated extensive research on alternatives to surfactant-stabilized CO2 foams for CO2 mobility control. The formation of CO2-in-water foams lowers the CO2 mobility, resulting in improvement in swee...

The utilization of nonionic surfactants for stabilization of CO2 foams has been limited by low aqueous solubilities at elevated temperatures and salinities. In this work, a nonionic surfactant C12-14(EO)22 with a high degree of ethoxylation resulted in a high cloud point temperature of 83 °C even in 90 g/L NaCl brine. Despite the relatively high hy...

Synergistic interactions between appropriately designed surface-modified nanoparticles and surfactants are shown to stabilize foams of CO2 bubbles/droplets dispersed in water at elevated temperature and pressure typical of subsurface formations for enhanced oil recovery or geologic storage of CO2. The foams are sufficiently viscous to mitigate or e...

Chemical formulations of nanoparticles and surfactants are developed to stabilize high internal phase carbon dioxide-in-water (C/W) foams for low water hydraulic fracturing fluids. Silica nanoparticles and low concentrations of surfactants that weakly interact with nanoparticles were used to stabilize the C/W foams. The surfactants are adsorbed ont...

Foams, dispersions of gases in liquids, are great substitutes for conventional hydraulic fracturing fluids. Conventional methods use water, chemical additives and thickeners such as guar gum to increase viscosity of the fluids. This enables the pad to carry proppants into the fractures. The problem with hydraulic fracking processes appears during f...

Dispersant systems for oceanic oil spill remediation have gained renewed attention following the Deepwater Horizon oil spill in 2010. The combination of surfactants and silica or clay nanoparticles and microparticles can provide synergy in the formation and stabilization of dodecane droplets in synthetic seawater. The surfactants lower the oil/wate...

The mechanism by which polymers, when grafted to inorganic nanoparticles, lower the interfacial tension at the oil-water interface is not well understood, despite the great interest in particle stabilized emulsions and foams. A simple and highly versatile free radical "grafting through" technique was used to bond high organic fractions (by weight)...

Environmentally benign clay particles are of great interest for the stabilization of Pickering emulsions. Dodecane-in-synthetic seawater (SSW) emulsions formed with montmorillonite (MMT) clay microparticles modified with bis(2-hydroxyethyl)oleylamine were stable against coalescence, even at clay concentrations down to 0.1 % w/v. Remarkably, as litt...

Ethoxylated amine surfactants of the form C12-14N(EO) x have been characterized for foam generation to improve the sweep efficiency for CO2 enhanced oil recovery (EOR) up to 120 °C in the presence of high salinity brine of 22%TDS. These surfactants are switchable from the nonionic (unprotonated amine) state in dry CO2 to cationic (protonated amine)...

To improve sweep efficiency for carbon dioxide (CO2) enhanced oil recovery (EOR) up to 120°C in the presence of high-salinity brine (182 g/L NaCl), novel CO2/water (C/W) foams have been formed with surfactants composed of ethoxylated amine headgroups with cocoalkyl tails. These surfactants are switchable from the nonionic (unprotonated amine) state...

We evaluate the transport of surface-treated superparamagnetic iron-oxide nanoparticles in Boise-sandstone rocks by injecting aqueous dispersions of the particles into core plugs. Several different surface treatments yield stable dispersions of these particles, but provide very different transport characteristics. Effluent concentration histories a...

Oil-in-water emulsions were formed and stabilized at low amphiphile concentrations by combining hydrophilic nanoparticles (NPs) (i.e., bare colloidal silica) with a weakly interacting zwitterionic surfactant, caprylamidopropyl betaine, to generate a high hydrophilic-lipophilic balance. The weak interaction of the NPs with surfactant was quantified...

Magnetic nanoparticles with high mobility in subsurface reservoirs at high salinities and temperatures are expected to have a major impact on enhanced oil recovery, carbon dioxide sequestration, and electromagnetic imaging. Herein we present a rare example of elelctrosteric stabilization of iron oxide (IO) nanoparticles (NPs) grafted with poly(2-ac...

The combination of zwitterionic surfactants and silica or clay nanoparticles and microparticles provides synergism in formation and stabilization of dodecane droplets in synthetic seawater. These combined amphiphiles are of interest for mitigation of oil leaks at the ocean floor. The surfactant lowers the oil/water interfacial tension and allows th...

Foams used for mobility control in CO2 flooding, and for more secure sequestration of anthropogenic CO2, can be stabilized with nanoparticles, instead of surfactants, bringing some important advantages. The solid nature of the nanoparticles in stabilized foams allows them to withstand the high-temperature reservoir conditions for extended periods o...

Synergistic interactions at the interface of nanoparticles (bare colloidal silica) and surfactant (caprylamidopropyl betaine) led to the generation of viscous and stable CO2-in-water (C/W) foams with fine texture at 19.4 MPa and 50°C. Interestingly, neither species generated C/W foams alone. The surfactant became cationic in the presence of CO2 and...

Magnetic nanoparticles that can be transported in subsurface reservoirs at high salinities and temperatures are expected to have a major impact on enhanced oil recovery, carbon dioxide sequestration, and electromagnetic imaging. Herein we report a rare example of steric stabilization of iron oxide (IO) nanoparticles (NPs) grafted with poly(2-acryla...

Transport of metal oxide nanoparticles in porous rock is of interest for imaging and oil recovery in subsurface reservoirs, which often contain concentrated brine. Various copolymers composed of acrylic acid and either 2-acrylamido-2-methylpropanesulfonate or styrenesulfonate were synthesized and adsorbed on iron oxide nanoclusters to provide collo...

A series of sulfonated random and block copolymers were adsorbed on the surface of ~100 nm iron oxide (IO) nanoclusters to provide colloidal stability in extremely concentrated brine composed of 8% wt. NaCl + 2% wt. CaCl2 (API brine; 1.4 M NaCl + 0.2 M CaCl2) at 90 °C. A combinatorial materials chemistry approach, which employed Ca2+-mediated adsor...

Minimizing the adsorption of engineered nanoparticles (NPs) on rock surface is paramount for feasibility of sub-surface applications and environmental fate of NPs. Natural reservoir brines often have high salinity including the presence of significant divalent cations including calcium that lead to strong NP adsorption. We recently identified a cla...

Electrosteric stabilization of copolymer-coated nanoparticles is uncommon for high monovalent salinity (upto 5 M NaCl), and rarely reported for concentrated divalent cations. However, high mono and divalent concentrations are routinely encountered in subsurface applications including electromagnetic imaging and oil recovery. Stabilization of nanopa...

The concept of hydrophilic/CO(2)-philic balance (HCB) was extended to describe stabilization of carbon dioxide-in-water (C/W) foams (also called emulsions) with silica nanoparticles adsorbed at the CO(2)-water interface. Opaque, white C/W foams (bubble diameter <100μm) were generated with either PEG-coated silica or methylsilyl modified silica nano...

Viscous C/W foams were generated without the use of polymers or surfactants by shearing CO 2 and an aqueous phase containing partially hydrophobic silica nanoparticles in a beadpack filled with 180μm glass beads. Silica particles with 50% SiOH coverage were chosen because they have a hydrophilicity that falls between the 42% SiOH optimum foaming ab...

Despite significant interest in CO 2 foams for EOR, very few studies have reported stable foams at high temperatures and high salinities, which are often encountered in the Middle East and elsewhere. Stable CO 2/water (C/W) foams at high temperatures up to 120°C and salinities have been achieved with ethoxylated cationic surfactants. The surfactant...

Mixtures of oppositely charged surfactants and polyelectrolytes self-assemble into a variety of nanostructured complexes. With the view of developing simpler and cleaner alternatives to synthetic nanomaterials, self-assembled nanostructures can be prepared from bioderived surfactant/polyelectrolyte mixtures. These complexes can be designed to vary...