Water‐soluble allyl and diallyl camphor sulfonamides‐based polyacrylamide copolymers for enhanced oil recovery

The monomers N‐allyl camphor sulfonamide (CSAP) and N,N‐diallyl camphor sulfonamide (CSDAP) were copolymerized with acrylamide (AM), acrylic acid (AA) for EOR, respectively. The effect of the synthesis conditions on apparent viscosity was investigated, and the copolymers were characterized by Fourier transform infrared spectroscopy (FTIR), ¹H nuclear magnetic resonance (¹H NMR), environmental scanning electron microscope (ESEM), and thermogravimetric analysis (TGA). Increasing mass ratio of diallyl CSDAP could lead to the water‐insoluble of copolymer, and competition of free radicals could make polymerization of AM/AA/CSDAP more difficult than AM/AA/CSAP. The thickening function and temperature resistance of two copolymers were remarkably improved in comparison with similar molecular weight partially hydrolyzed polyacrylamide (HPAM). In addition, the pronounced temperature resistance of the copolymers has been also demonstrated by temperature resistance test. It has also found that copolymers AM/AA/CSAP and AM/AA/CSDAP brine solutions could obtain significant enhanced oil recovery at 70°C suggesting their potential being applied in chemical enhanced oil recovery. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41238.     

Modification of a nicotinic acid functionalized water‐soluble acrylamide sulfonate copolymer for chemically enhanced oil recovery

N,N‐Diallyl nicotinamide (DANA) and acrylic acid (AA) were used to react with acrylamide (AM) and synthesize a novel nicotinic acid functionalized water‐soluble copolymer AM/AA/DANA by redox free‐radical polymerization. Then, the acrylamide/sodium acrylamido methanesulfonate/acrylic acid/N,N‐diallyl nicotinamide (AM/AMS/AA/DANA) was obtained by the introduction of the ? SO₃^? group into AM/AA/DANA after sulfomethylation. The optimal reaction conditions, such as the monomer ratio, initiator concentration, reaction temperature, and pH of the copolymerization or sulfomethylation, were investigated. Both AM/AA/DANA and AM/AMS/AA/DANA were characterized by IR spectroscopy, ¹H‐NMR, scanning electron microscopy, and intrinsic viscosity testing. We found that the AM/AMS/AA/DANA had a remarkable temperature tolerance (120°C, viscosity retention rate = 39.8%), shear tolerance (1000 s^?1, viscosity retention rate = 23.3%), and salt tolerance (10 g/L NaCl, 1.5 g/L MgCl₂, 1.5 g/L CaCl₂, viscosity retention rates = 37.4, 27.5, and 21.6%). In addition, the result of the core flood test showed that the about 13.1% oil recovery could be enhanced by 2.0 g/L AM/AMS/AA/DANA at 70°C. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40165.     

Vermiculite/polyacrylamide copolymers microspheres for profile control in oilfields

Polyacrylamide copolymers (PAMVT) microspheres were prepared through inverse emulsion polymerization by using acrylic acid (AA), 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) as functional monomers, N,N′‐methylene bis‐acrylamide (MBA) as crosslinker and modified vermiculite (MVMT) with the single‐factor experiments. The initial and swelled particle sizes were tested through the dynamic light scattering (DLS). The swelled particle size under the optimum conditions could be 1.98 μm. The structure was characterized through Fourier transform infrared (FTIR), which indicated that vermiculite has successfully modified and the polymerization reaction was completed. The scanning electron microscopy (SEM) shows that MVMT was evenly filled with PAM copolymers. The water absorption capacity can be up to 80.2%. The recovery efficiency of the water flooding was increased from 69.33% to 77.56%. All these results indicated that the microspheres emulsions could be used as profile control agent to enhance the recovery efficiency. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44918.     

A water‐soluble acrylamide hydrophobically associating polymer: Synthesis,characterization, and properties as EOR chemical

A water‐soluble acrylamide hydrophobically associating terpolymer for polymer flooding was successfully synthesized via free radical polymerization using acrylamide (AM), acrylic acid (AA), and N,N‐divinylnonadeca‐1,10‐dien‐2‐amine (DNDA) as raw materials. The terpolymer was characterized by IR spectroscopy and fluorescence spectra. Compared with partially hydrolyzed polyacryamide (HPAM), the terpolymer showed a stronger link and better dimensional network structure under the environmental scanning electron microscope (ESEM). The results of rheology indicated that the terpolymer (AM‐NaAA‐DNDA) showed an excellent shear‐resistance in high shear rate (1000 s^?1) and remarkable temperature‐tolerance (above 110°C). The salt‐resisting experiment revealed that this terpolymer had a better anti‐salt ability. According to the core flooding test, it could be obtained that oil recovery was enhanced more than 15% under conditions of 2000 mg/L terpolymer in the mineralization of 8000 mg/L at 60°C. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Rheological investigation of a random copolymer of polyacrylamide and polyacryloyl hydrazide (PAM‐ran‐PAH) for oil recovery applications

In this article, we synthesize and investigate the rheological properties of a random copolymer PAM‐ran‐PAH of polyacrylamide (PAM) and polyacryloyl hydrazide (PAH) and compare with the results of PAM at different temperature (30 and 80 °C) and salinity (0 and 1.0 wt %). At 30 °C, both PAM and PAM‐ran‐PAH exhibited non‐Newtonian rheology with both shear thinning and shear thickening responses. The rheological properties such as viscosity and moduli (G′ and G″) of PAM significantly deformed at elevated temperature (80 °C) and salinity (1.0 wt %), resulting no recovery in viscosity and moduli. On the other hand, the effect of temperature and salinity was found to be least on PAM‐ran‐PAH and showed better stability with the possibility of recovering its original rheological properties. The performance of PAM and PAM‐ran‐PAH was also characterized by enhanced oil recovery tests. The use of PAM‐ran‐PAH for polymer flooding, due to its stable rheology, resulted in an increase in the oil recovery than PAM. In general, the rheological behavior of PAM‐ran‐PAH as a chemical agent proved to be thermally stable than PAM, which clearly supports its use for saline environment and high temperature applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44648.     

High‐temperature resistance water‐soluble copolymer derived from acrylamide,DMDAAC, and functionalized sulfonamide for potential application in enhance oil recovery

A water‐soluble poly(AM‐AA‐DMDAAC‐TCAP) was prepared using acrylamide (AM), acrylic acid (AA), diallyl dimethyl ammonium chloride (DMDAAC), and N‐allyl‐4‐methylbenzenesulfonamide (TCAP), and the synthesis conditions were investigated. The obtained copolymer was characterized by FTIR, ¹H‐NMR, SEM, TG, and XRD. The temperature resistance and thickening function of the copolymer are improved significantly compared with that of partially hydrolyzed polyacrylamide. It is found that the viscosity of copolymer could achieve up to 53.3% retention rate at 120°C compared to that at 30°C. About 16.6% for enhanced oil recovery is obtained by poly(AM‐AA‐DMDAAC‐TCAP) brine solution at 65°C. In addition, the results of XRD show that 3000 mg/L copolymer combined with 10 wt % KCl solution could reduce the d‐spacing of sodium montmorillonite from 18.94 to 14.86 Å exhibiting remarkable effect on inhibiting hydration of clays. All the results demonstrate that poly(AM‐AA‐DMDAAC‐TCAP) have excellent performance for potential application in enhance oil recovery. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40727.     

Research on synthesis and thermal properties of poly(ethylene terephthalate) sulfonate group containing ionomer

In order to solve the poor nucleation ability and slow crystallization rate of polyethylene terephthalate (PET), we propose a new strategy to prepare PET with self-nucleation ability based on the mechanism of mutual attraction of ions. In this study, a hydroxyl-terminated sulfonate monomer, sulfonated 1,4-butanediol (SBDO) without rigid structure was synthesized as nucleating agent functionalized PET third monomer, and then PET ionomers (PETi) were prepared through melt polycondensation with different contents of SBDO. The half-crystallization time of PETi was sharply decreased in contrast with pure PET and the crystallization temperature was significantly increased from 182.6°C to 210.8°C for PETi1. Due to the high nucleation efficiency of SBDO, the crystallization temperature of PET was significantly increased, avoiding the excessive addition of traditional nucleating agents to deteriorate the mechanical properties of PET. The increased nucleation efficiency was contributed to the aggregation of SBDO induced by the ionic interactions.     

Synthesis of comb‐type copolymers with various pendants and their effect on the complex rheological behaviors of waxy oils

To improve the flowability of waxy crude oil containing a high concentration of asphaltenes (AS), novel comb‐type copolymers of poly(maleic acid polyethylene glycol ester‐co‐α‐octadecene) (PMAC) and poly(maleic acid aniline amide‐co‐α‐octadecene) (AMAC) with various grafting ratios (R_g) of PEG/aniline to maleic anhydride are synthesized. Model oils containing wax mixtures and AS are prepared to explore the effect of asphaltene concentration and the copolymers on the yield stress. The influence of the copolymers on the wax appearance temperature (WAT) of Liaohe high waxy oil is examined by rheological and microscopic methods. Experimental flow curves of shear stress as a function of shear rate are fitted following the Casson model to interpret the rheological properties of gelled waxy crude oil in the presence of AMACs, PMACs, and MAC. Compared with MAC, PMACs, and AMACs are more efficient in reducing the yield stress of both model oil and crude oil, which indicates a better flowability. It is found that PMAC1.0 and AMAC1.0 with a medium R_g can balance the interaction of copolymers with waxes and AS and reduce the yield stress much more than others. Between them, AMAC1.0 that possesses aromatic pendants is better than PMAC1.0, which only has polar pendants. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41660.     

Preparation and properties of a polyether‐based polycarboxylate as an antiscalant for gypsum

A polyether‐based copolymer of acrylic acid‐allylpolyethoxy maleic carboxylate (AA‐APEY) was prepared by copolymerization of allylpolyethoxy carboxylate (APEY) and acrylic acid (AA) at different mole ratios. The main aim of this work was to investigate the influence of AA‐to‐APEY mole ratios on the copolymer properties and scale inhibition performance for gypsum. The synthesized copolymer was characterized by Fourier‐transform infrared (FT‐IR) and further conformed by ¹H NMR. The effect of AA‐APEY on controlling calcium sulfate deposits was studied through static scale inhibition tests under standard solution conditions. And the result was compared with that of other polycarboxylates, which are similar to AA‐APEY in structure. Scanning electronic microscopy (SEM), transmission electron microscopy (TEM), and X‐ray powder diffraction (XRD) analysis were carried out to study the morphology and structure changes of calcium sulfate crystals in the presence of AA‐APEY. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40193.     

Capillary breakup extensional rheometry of associative and hydrolyzed polyacrylamide polymers for oil recovery applications

High molecular weight polymers used for heavy oil recovery exhibit viscoelasticity that can influence the oil recovery during chemical enhanced oil recovery. Different polymers having similar molecular weight and shear rheology may have different elongation flow behavior depending on their extensional properties. Displacing slugs are more likely to stretch than shear in tortuous porous media. Therefore, it is critical to seek an analytical tool that can characterize extensional parameters to improve polymer selection criteria. This article focuses on the extensional characterization of two polymers (hydrolyzed polyacrylamide and associative polymer) having identical shear behavior using capillary breakup extensional rheometer to explain their different porous media behavior. Maximum extensional viscosity at the critical Deborah number and Deborah number in porous media classified the associative polymer as the one having high elastic‐limit. Extensional characterization results were complemented by significantly higher pressure drop, marginally increased oil recovery of associative polymer in porous media. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46253.     

Polyethersulfone/polyetherethersulfone copolymers with the same chemical composition and different melt‐viscosity

Random, block, and alternative polyethersulfone/polyetherethersulfone copolymers (phenyl: ether: sulfone =7 : 4 : 3) with similar molecular weights and polydispersity were synthesized using different synthetic strategies. DSC and DMA analyses indicated that all copolymers are amorphous and possess extremely close glass transition temperature. The random copolymer displayed higher modulus and complex viscosity. It is interesting to find that the alternative copolymer exhibited a melt viscosity of 281 Pa s, which is much lower than that of the block copolymer (646 Pa s) and the random copolymer (1641 Pa s) at 4 s^?1. Moreover, the alternative copolymer showed obviously higher elongation at break of 101.9%. These behaviors were highly related to their different sequence distribution. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40149.     

Gelation mechanism and rheological properties of polyacrylamide crosslinking with polyethyleneimine and its plugging performance in air‐foam displacement

Gels based on polyacrylamide crosslinking with polyethyleneimine have attracted attention because of their resulting high strength and good thermal stability. This study investigated the gelation mechanism of the polymeric gel and its plugging performance in air‐foam flooding. An optic microrheology analyzer was used to monitor the gelation process. The crosslinking reaction occurred in two steps, as determined from the elasticity factor curves, and the polymeric gels adopted a semisolid state from solution, as determined from the solid liquid balance curves. The elastic modulus values were higher than the viscous modulus values, indicating that mature gels were elastic‐based materials. The yield stress increased gradually with increasing polymer dosage, which was consistent with the breakthrough pressure and the trend of displacement pressure. The mature gels showed significant thixotropy. In the core displacement test, the preferred injection volume of the gel was 0.1 pore volume, and the stable pressure of the foam flooding was increased by about three times after the core was plugged. The blocking effect for cores with small original permeability was better than that with large permeability. The best blocking resulted from simultaneous treatment of both ends of the cores, followed by front‐end treatment and rear‐end treatment. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45778.     

Enhancement of rheological and mechanical properties of bitumen using styrene acrylonitrile copolymer

In this research, styrene acrylonitrile copolymer as a novel additive is used to modify rheological, mechanical and thermal properties of the base bitumen 70 penetration grade. Styrene acrylonitrile copolymer combines the rigidity of polystyrene with the hardness and thermal resistance of polyacrylonitrile to enhance viscoelastic property of the bitumen. To investigate the performance of the proposed mixture, shear complex module, phase angle, penetration, softening point, and reversibility of prepared samples are measured at different additive content and compared with the base bitumen. The results show that softening point of the base and modified samples are 49–86°C, respectively. The rheological properties of the base bitumen and modified samples are measured by a dynamic shear rheometer (DSR). The phase angle as elasticity measure decreases from 55° to 35° in the modified bitumen compared to the base bitumen. Generally, the experimental results showed that styrene acrylonitrile copolymer makes bitumen to be more stable at high temperatures and more flexible at low temperatures. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41875.     

New insights into the viscosity features of cationic polyacrylamide microgels in aqueous solutions

Increasing attention has recently been paid to the rheological behavior of microgel colloids and to the physical forces that control their behavior. Here, based on a series of cationic microgels that were synthesized by inverse microemulsion polymerization, the physical forces were explored by viscosity analysis of swollen microgels with different crosslinking densities and cationic contents. The results indicate that within a wide concentration range, the viscosity curves for these cationic microgels perfectly correspond to the Krieger–Dougherty model as modified by Tan et al. In particular, the specific volume in this model decreases at the critical overlapping concentration and reveals the interaction intensity between neighboring microgels. Furthermore, the viscosity index in the Herschel–Bulkley equation indicates that the interaction domain among microgels undergoes a transfer from an electroviscous effect to osmotic deswelling with increasing concentrations. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46297.     

New filtrate loss controller based on poly(methyl methacrylate‐co‐vinyl acetate)

The drilling of petroleum wells requires the use of suitable drilling fluids to ensure efficient operation without causing rock damage. Specific polymers have been used to control infiltration during drilling, to reduce operational problems. In this study, spherical microparticles of poly(methyl methacrylate‐co‐vinyl acetate) were synthesized (by suspension polymerization), characterized, and evaluated in terms of their performance in controlling filtrate loss of aqueous fluids. A filter press test with ceramic disk, simulating the rock, was used. The performance of the synthesized materials was compared with commercial polymers. It was observed that the performance of the material is directly associated with the relation between particle size and pore size of the rock specimen. Furthermore, for a suitable particle size, the rubbery characteristic of the material produces a more efficient filter cake, for filtrate control. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40646.     

Enhancing rheological properties of hydrophobically associative polyacrylamide aqueous solutions by hybriding with silica nanoparticles

Organic/inorganic hybrid aqueous solutions were prepared by mixing silica nanoparticle suspension and hydrophobically associating polyacrylamide (HAPAM) solution, and their rheological behaviors were examined in both pure water and brine in comparison with HAPAM. It was found that HAPAM/silica hybrid exhibits viscosity enhancement in aqueous solution and better heat‐ and salt‐ tolerances than HAPAM. Meanwhile, their long‐term thermal stability is also improved. Cryo‐TEM observation reveals that a reinforced three‐dimensional network structure of HAPAM/silica hybrid is formed. These improved properties are attributed to the formed hydrogen bond between carbonyl groups in HAPAM skeleton and silanol functionalities in silica nanoparticles in the hybrid system, and the silica nanoparticles in the hybrid act as physical crosslinkers between macromolecules. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40876.     

Rheological properties of a hydrophobically modified anionic polymer: Effect of varying salinity and amount of hydrophobic moieties

Hydrophobically modified polyelectrolytes have been suggested as an alternative to the more commonly used polyelectrolytes in enhanced oil recovery (EOR) applications involving polymers. Compared to regular polyelectrolytes, the hydrophobically modified polyelectrolytes are known to be more stable at high salinities. In this study, we have investigated the influence of brine salinity and ionic composition for a series of six hydrophobically modified polyelectrolytes with the same polymer backbone, but with an increasing average number of hydrophobic groups per polymer molecule. Polymer characterization has been performed using a combination of steady‐state shear viscosity and dynamic oscillatory measurements. Hydrophobic interactions leading to a change in rheological properties was only observed above a threshold value for the concentration of hydrophobe. At the threshold value, salt‐induced hydrophobic interactions were observed. For higher concentrations of hydrophobe, high salinity solutions showed one order of magnitude increase in viscosity compared to the polymer without hydrophobic groups. This could partly be explained by an increase in elasticity. These findings have important implications for polymer selection for EOR. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43520.     

Nonlinear rheological behavior of a novel oil displacing agent

In this work, the shear and elongational rheologies have been investigated for a newly developed oil displacing agent, polymeric surfactant‐PSf. It was found that the PSf solutions exhibited Newtonian, shear‐thinning, and shear‐thickening behavior, respectively, depending on the polymer concentration and shear rate, and Cox–Merz rule was not applicable to these systems. The first normal stress difference (N₁) versus shear rate plots for PSf were complicated, which varied with the composition of the solutions. The uniaxial elongation in capillary breakup experimental results indicated that Exponential model could be used to fit the experimental data of the PSf solutions at lower polymer concentrations. In addition, it was found that PSf was more effective in improving shear viscosity than partially hydrolyzed polyacrylamide, but not in the case of elongational viscosity. The experimental results indicated that the microstructural mechanisms are responsible for the rheological behavior of the polymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40813.     

Development of active barrier systems for poly(ethylene terephthalate)

Copolymers of Poly(ethylene terephthalate) (PET) were synthesized by the melt polymerization of terephthalic acid (TPA) with ethylene glycol (EG) and with each of the active oxygen scavengers; monoolein (MO) and 3‐cyclohexene‐1,1‐dimethanol (CHEDM) in separate compositions. Proton nuclear magnetic resonance spectroscopy (¹H NMR) and 2D correlation spectroscopy (COSY) indicated that PET had reacted with both MO and CHEDM at their hydroxyl end groups. Oxygen barrier properties of the MO and CHEDM copolymers exhibited improvements of up to 40%, in comparison to an unmodified commercial PET. Effects of the oxygen scavengers on the copolymers' physical properties were investigated in terms of their crystallization, melting, and rheological behaviors. Both types of copolymers showed decreases in peak melting temperatures with increased scavenger concentrations and also crystallized more slowly as the scavenger concentrations increased. The PET/MO copolymer showed non‐Newtonian rheological behavior with higher MO concentration; while the PET/CHEDM copolymers showed Newtonian behavior within the studied range of CHEDM concentrations. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013