Polymers for enhanced oil recovery: A paradigm for structure–property relationship in aqueous solution

The rheology of aqueous solutions of ethyl hydroxy-ethyl cellulose (EHEC) and its hydrophobically modified analogue (hmEHEC): extensional flow response in capillary break-up, jetting (ROJER) and in a cross-slot extensional rheometer

Cellulose derivatives containing associating hydrophobic groups along their hydrophilic backbone are used as rheology modifiers in the formulation of water-based spray paints, medicinal sprays, cosmetics and printable inks. Jetting and spraying applications of these materials involve progressive thinning and break-up of a fluid column or sheet into drops. Strong extensional kinematics develop in the thinning fluid neck. In viscous Newtonian fluids, inertial and viscous stresses oppose the surface tension-driven instability. In aqueous solutions of polymers such as Ethyl Hydroxy-Ethyl Cellulose (EHEC), chain elongation provides additional elastic stresses that can delay the capillary-driven pinch-off, influencing the sprayability or jettability of the complex fluid. In this study, we quantify the transient response of thinning filaments of cellulose ether solutions to extensional flows in a Capillary Break-up Extensional Rheometer (CaBER) and in a forced jet undergoing break-up using Rayleigh Ohnesorge Jetting Extensional Rheometry (ROJER). We also characterize the steady state molecular deformations using measurements of the flow-induced birefringence and excess pressure drop in an extensional stagnation point flow using a Cross-Slot Extensional Rheometer (CSER). We show that under the high extension rates encountered in jetting and spraying, the semi-dilute solutions of hydrophobically modified ethyl hydroxy-ethyl cellulose (hmEHEC) exhibit extensional thinning, while the unmodified bare chains of EHEC display an increase in extensional viscosity, up to a plateau value. For both EHEC and hmEHEC dispersions, the low extensibility of the cellulose derivatives limits the Trouton ratio observed at the highest extension rates attained (close to 10(5) s(-1)) to around 10-20. The reduction in extensional viscosity with increasing extension rate for the hydrophobically modified cellulose ether is primarily caused by the disruption of a transient elastic network that is initially formed by intermolecular association of hydrophobic stickers. This extensional thinning behavior, in conjunction with the low extensibility of the hydrophobically modified cellulose ether additives, makes these rheology modifiers ideal for controlling the extensional rheology in formulations that require jetting or spraying, with minimal residual stringiness or stranding.

Oil/water Interfacial Tension of Shengli Petroleum Sulfonate/α-Olefin or Polyethyleneoxy Ether Sulfonate Binary Systeme

As one important parameter for selecting surfactant used in chemistry flooding, here the interfacial tension (IFT) between crude oil and single surfactants Shengli petroleum sulfonate (SHL-PS), α-olefin sulfonate (C14/16AOS), fatty alcohol polyethyleneoxy ether sulfonate (CnEmSO) or their mixture using mimic Shengli brine water as solvent were investigated using spinning drop technology. The results showed: Through C18E3SO has a small ultra-low IFT window, it is more practical and efficient to obtain ultra-low IFT by mixing two or more surfactants other than using single surfactant; the length of hydrophobic tail plays a more important role than oxyethylene group number on the IFT for CnEmSO/SHL-PS; at mass ratio 1:19, both C14/16AOS/SHL-PS and C18EmSO/SHL-PS systems can lower the IFT to below 10−2 mN/m, but their mechanisms may be not same.

Atomistic molecular dynamics simulations of carbohydrate-calcite interactions in concentrated brine

We report atomistic molecular dynamics simulations to study the interactions of a model carbohydrate monomer (Glucopyranose) and calcite slabs in brine. We show that the interactions between the sugar molecules and the mineral decrease with increasing salinity. The decrease is due to the formation of salt layers on the calcite surfaces, which screen the carbohydrate-calcite hydrogen bonding. This screening effect depends on the affinities of calcite surface to specific ions as well as to the carbohydrate molecules.

Composition and structural transitions of polyelectrolyte-surfactant complexes in the presence of fatty acid studied by NMR and cryo-SEM

Insoluble complexes formed when a cationic polyelectrolyte is neutralized by the oppositely charged surfactant sodium dodecylethersulfate (SDES) in the presence and absence of lauric acid (LA) have been examined directly using NMR spectroscopy and cryo-SEM. Below the SDES critical micelle concentration (CMC') the insoluble complex contains about 10 times more water than just above CMC'. This is related to a structural transition of the complex, where water is contained mainly in larger compartments below CMC' and then mainly in narrower compartments above CMC'. The structure of the complex's solid matrix was monitored by recording two-dimensional T2-diffusion correlation spectra of the water proton resonance, which reveal the presence of several different water environments which correspond to different complex structures. Structural features in the micrometer range were confirmed using cryo-SEM. When LA is present, the larger water compartments seen below CMC' are to some extent present in the entire SDES concentration range, which is not the case in the absence of LA. Furthermore, the inclusion of LA into the SDES aggregates above CMC' leads to a lamellar sheetlike organization of the polyelectrolyte-stabilized surfactant phase. In the absence of LA, a stringy network of fibers is seen in cryo-SEM images, indicating a spherical or rodlike SDES phase. Consequently, the complex without LA holds about 1.7-1.9 times more water than the complex with LA above the SDES CMC'. T1 relaxation, (13)C chemical shifts, and (1)H resonance line widths of SDES in the system support the above observations. The combination of MAS NMR, T2-diffusion correlation, and cryo-SEM proved to be an effective method for studying structural transitions in the surfactant-polyelectrolyte(-LA) insoluble complexes.

Synergistic mechanism between laurel alkanolamide and hydrophobically associating polyacrylamide in solutions with high salinity

The hydrophobic interaction between laurel alkanolamide micelles and hydrophobically associating polyacrylamide enhances the formation of network structure and the viscosity of the mixed solution increases in a large electrolyte concentration range.

Preparation and Performance of an Adsorption Type Gel Plugging Agent as Enhanced Oil Recovery Chemical

A novel adsorption type gel plugging agent (ATGPA) was prepared using acrylamide (AM), acrylic acid (AA), diallyl dimethyl ammonium chloride (DMDAAC), 2-acrylamido-2-methylpropanesulfonate (AMPS), formaldehyde (HCHO), resorcinol (C6H6O2), and thiocarbamide (CH4N2S) as raw materials under mild conditions. ATGPA was characterized by infrared (IR) spectroscopy, elemental analysis, and scanning electron microscope (SEM). It was found that ATGPA exhibited higher elastic modulus (G′) and viscous modulus (G′′) than AM/AA gel plugging agent (AAGPA) under the same scanning frequency. It was also found that ATGPA had moderate temperature resistance and salt tolerance. Core plugging tests results indicated that ATGPA could achieve up to higher plugging rate (PR) than AAGPA (97.2% versus 95.7%) at 65°C. In addition, ATGPA possessed stronger antiscouring ability by core plugging experiments at 65°C.

Thermally stable imidazoline-based sulfonate copolymers for enhanced oil recovery

Novel water-soluble imidazoline-based sulfonate copolymers were synthesized; the copolymers possess excellent thermal stability and outstanding potential for application in high-temperature oil recovery.

Synthesis of polyacrylamides hydrophobically modified with butyl acrylate using a nanoclay with interlayer spaces for butyl acrylate aggregation: studies on the microstructure and aqueous solution viscosity

Aqueous solution copolymerization of acrylamide and butyl acrylate can be affected by the hydrophobic nature of the nanoclay, resulting in different copolymer microstructures.

A water-soluble oil-displacing agent with tracer properties for enhancing oil recovery

A water-soluble fluorescent oil-displacing agent was prepared via copolymerization of acrylamide (AM), acrylic acid (AA) and coumarin derivatives (CO) for enhancing oil recovery.

Solution properties and phase behavior of a combination flooding system consisting of hydrophobically amphoteric polyacrylamide, alkyl polyglycoside and n-alcohol at high salinities

Application of polymer/surfactant (SP) combination flooding technique is attracting considerable interest in enhanced oil recovery (EOR).

Amphoteric hyperbranched polymers with multistimuli-responsive behavior in the application of polymer flooding

Amphoteric hyperbranched polymers (AMHPMs) that respond to shear rate, temperature, salt, and pH were synthesized using a water free radical polymerization technique.

Zwitterionic copolymer-based and hydrogen bonding-strengthened self-healing hydrogel

We report here a zwitterionic copolymer based non-covalently cross-linked hydrogel with intrinsic self-healing nature for potential use in enhanced oil recovery.

An anti-biodegradable hydrophobic sulfonate-based acrylamide copolymer containing 2,4-dichlorophenoxy for enhanced oil recovery

We report the synthesis of a novel hydrophobic sulfonate-based acrylamide copolymer which exhibits remarkable water solubility, excellent resistance to biodegradability, and superior ability to enhance oil recovery.

A water-soluble antimicrobial acrylamide copolymer containing sulfitobetaine for enhanced oil recovery

A novel antimicrobial copolymer containing sulfitobetaine is studied and has excellent application potential in EOR.

Iron Oxide Nanoparticles Grafted with Sulfonated and Zwitterionic Polymers: High Stability and Low Adsorption in Extreme Aqueous Environments

A facile "grafting through" approach was developed to tether tunable quantities of poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) as well as zwitterionic poly([3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium hydroxide) (PMPDSA) homopolymer onto iron oxide (IO) nanoparticles (NPs). In this case, homopolymers may be grafted, unlike "grafting to" approaches that often require copolymers containing anchor groups. The polymer coating provided steric stabilization of the NP dispersions at high salinities and elevated temperature (90 °C) and almost completely prevented adsorption of the NPs on silica microparticles and crushed Berea sandstone. The adsorption of PAMPS IO NPs decreased with the polymer loading, whereby the magnitude of the particle-surface electrosteric repulsion increased. The zwitterionic PMPDSA IO NPs displayed 1 order of magnitude less adsorption onto crushed Berea sandstone relative to the anionic PAMPS IO NPs. The ability to design homopolymer coatings on nanoparticle surfaces by the "grafting through" technique is of broad interest for designing stable dispersions and modulating the interactions between nanoparticles and solid surfaces.