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.     

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.     

Hydrophobically associating acrylamide‐based copolymer for chemically enhanced oil recovery

A hydrophobically associating copolymer was prepared by free‐radical polymerization with acrylamide (AM), acrylic acid (AA), and N‐allyloctadec‐9‐enamide (NAE) as monomers. The structure was characterized by Fourier transform infrared spectroscopy, ¹H‐NMR, ¹³C‐NMR, and scanning electron microscopy. The rheological experiments indicated that the copolymer possessed superior properties compared with partially hydrolyzed polyacryamide. It was found that an AM/AA/NAE/Tween‐80 system could effectively decrease the interfacial tension and reduce the surfactant loss caused by stratum adsorption in polymer–surfactant flooding. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2901–2911, 2013     

Amphiphilic copolymers based on PEG‐acrylate as surface active water viscosifiers: Towards new potential systems for enhanced oil recovery

With the purpose of investigating new potential candidates for enhanced oil recovery (EOR), amphiphilic copolymers based on Poly(ethylene glycol) methyl ether acrylate (PEGA) have been prepared by Atom Transfer Radical Polymerization (ATRP). A P(PEGA) homopolymer, a block copolymer with styrene PS‐b‐P(PEGA), and an analogous terpolymer including also sodium methacrylate (MANa) in the poly(PEGA) (PPEGA) block, PS‐b‐P(PEGA‐co‐MANa) have been prepared and characterized. Viscosity and surface activity of solutions of the prepared polymers in pure and salty water have been measured and the results have been interpreted in terms of the chemical structures of the systems. A clear influence of the presence of the charged MANa moieties has been observed in both rheological and interfacial properties. The PS‐b‐P(PEGA‐co‐MANa) terpolymer, being an effective surface active viscosifying agent, is a good candidate as polymeric surfactant for applications in enhanced oil recovery and related. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44100.     

Modified polyacrylamide containing phenylsulfonamide and betaine sulfonate with excellent viscoelasticity for EOR

The monomers containing phenylsulfonamide N-allyl-4-methylbenzenesulfonamide (TCAP) and N,N-diallyl-4-methyl benzenesulfonamide (TCDAP) were copolymerized with acrylamide (AM), acrylic acid (AA), and 3-(3-methacrylamidopropyl-dimethylammonio)-propane-1-sulfonate (MDPS), respectively, through free-radical micellar copolymerization in deionized water for enhanced oil recovery (EOR). Then, the effect of the synthesis conditions was investigated simultaneously; the copolymers were characterized by Fourier transform infraredFTIR, nuclear magnetic resonance, scanning electron microscopy, and thermogravimetric analysis. It was found that the thickening function, high-temperature resistance (120 °C), and anti-shear ability were improved significantly. It was also found that the copolymers had excellent viscoelasticity at the lower shear frequencies. When the copolymers were dissolved in 10,000 mg L⁻¹ NaCl, 2000 mg L⁻¹ CaCl₂, and 2000 mg L⁻¹ MgCl₂ solutions, the viscosity retention rates of AM/AA/TCAP/MDPS and AM/AA/TCDAP/MDPS were 13.3, 11.1, 10.6% and 18.6, 15.2, 11.7%, respectively. In addition, the copolymers for EOR at 60 °C were 11.4 and 13.8%, respectively, which demonstrated that the copolymers possessed excellent performance for potential application in EOR. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47971.     

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.     

Self‐assembled acrylamide‐based copolymer/surfactant with high‐temperature resistance for enhanced oil recovery

In this article, we report on a water‐soluble self‐assembled system that consisted of an acrylamide (AM)‐based copolymer and a nonionic surfactant for enhancing oil recovery. The copolymer, denoted as poly(acrylamide–acrylic acid–diallyl dimethyl ammonium chloride–N ‐allyl benzamide) (PMADN), was synthesized with AM, acrylic acid, diallyl dimethyl ammonium chloride, and N ‐allyl benzamide, and the nonionic surfactant was Tween 40. The results of our investigation of the ratio of the copolymer to Tween 40 show that the optimal concentrations of PMADN and Tween 40 were 1000 and 500 mg/L, respectively. When it was heated to 115–120 °C for 15 min, the apparent viscosity of the self‐assembly system increased 19.2%, and its viscosity retention rate remained at 11.6% under 1000 s^?1. When the system was dissolved in 12,000 mg/L NaCl, 2000 mg/L CaCl₂, and 2000 mg/L MgCl₂ solutions, the viscosity retention rates were 22.3%, 12.1%, and 17.6%, respectively. In addition, a 2000 mg/L PMADN–Tween 40 solution dramatically enhanced the oil recovery up to 13.4%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45202.     

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.     

Mechanical stability of high‐molecular‐weight polyacrylamides and an (acrylamido tert‐butyl sulfonic acid)–acrylamide copolymer used in enhanced oil recovery

High‐molecular‐weight partially hydrolyzed and sulfonated polyacrylamides are widely used in enhanced oil recovery (EOR). Nonionic polyacrylamide and polyacrylamide‐based microgels are also used in water shut‐off treatments for gas and oil wells. A comparative study of the mechanical degradation for three linear polyacrylamides and a microgel is presented. Mechanical degradation is quantified from the loss of the viscosity of the polymer solution as it passes through a stainless steel capillary with a length of 10 cm and an internal diameter of 125 µm. The critical shear rate above which degradation increases exponentially was found to depend on the chemical structure of the polymer, molecular weight, and electrolyte strength. The nonionic polyacrylamide shows higher degradation and lower critical shear rate compared with a sulfonated polyacrylamide with similar molecular weight. Moreover, the nonionic polyacrylamide with a higher molecular weight results in lower mechanical degradation. The higher mechanical stability of the sulfonated polymer is attributed to the higher rigidity of its molecules in solution. On the other hand, the ability of the high‐molecular‐weight polymers to form transient, flow‐induced microgels boost their mechanical stability. This ability increases with the increase in the molecular weight of the polymer. Indeed, the microgel solution used in this study demonstrates exceptional mechanical stability. In general, mechanical stability of linear polymers used in chemical enhanced oil recovery can be enhanced by tailoring a polymer that has large side groups similar to the sulfonated polyacrylamide. Also, polyacrylamide‐based microgels can be applied if high mechanical stability is required. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40921.     

Water‐free synthesis of temperature‐sensitive polyacrylamide microgels and pore modeled oil recovery performance

Polymer gel treatments can improve sweep efficiency and reduce water production during oil recovery operations. In this article, a novel suspension polymerization method was developed to synthesize a temperature‐sensitive microgel. The microgel was prepared by suspension polymerization above the melting point of the monomer in a nonpolar solvent without water. Dry microspheres were obtained, which can be readily used without post‐treatment. Two different crosslinkers were employed in the suspension polymerization synthesis to give the particles thermally responsive aqueous swelling properties. After entering pore channels, gel particles expand to engineered size to realize flow profile changes within in a reservoir formation. When dispersed into water under lower temperatures (ambient to 40 °C), the original dry particles can swell about 18 times their original size. Exposure to a harsher environment (e.g., 80 °C) resulted in cleavage of the labile crosslinking agent and some chain cleavage gave a further size expansion. A Millipore film filtration model system was adopted to evaluate pore occlusion performance of the gel particles. It was found that the nuclear pores were effectively sealed by swollen microgels only when gel particle sizes were similar to or smaller than the membrane pores and interpore separation distance. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44581.     

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.     

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.     

Reversibly crosslinked self‐healing PCL‐based networks

Poly(ε‐caprolactone) (PCL)‐based thermoreversible networks with self‐healing properties were prepared through Diels–Alder (DA) and retro‐DA reactions. Bis‐ or Tris‐maleimide compounds and a series of copolymer(caprolactone‐diene) PCL_XF_Y (X: degree of polymerization and Y: furan‐average functionality) with Y between 2.4 and 4.9 were used. The successive sequences of formation and dissociation of polycaprolactone networks via DA and retro‐DA reactions were observed repeatedly by dynamic mechanical analyses (DMA) and their gel‐temperatures determined. The cross‐linking densities, thermal properties, and thermal reversibility of the PCL_XF_Y/multimaleimide polymers have been modulated by the structure and functionalities of the used diene and dienophile moieties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

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.     

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     

Rheology and polymer flooding characteristics of partially hydrolyzed polyacrylamide for enhanced heavy oil recovery

Polymer flooding characteristics of partially hydrolyzed polyacrylamide (HPAM) solution with the addition of NaOH were examined in homogeneous glass‐bead packs. The heavy oil recovery in unconsolidated sandstone formations by applying the alkali‐polymer flooding was observed. Experimental results showed that HPAM solution was sensitive to temperature, salinity, and alkali, finding that alkali‐polymer solutions are more effective in improving viscosity than conventional polymer solutions. The solution of 0.5 wt % NaOH mixed with 1500 ppm HPAM (12 mol % hydrolysis degree) was found to be the optimal choice, which gives rise to the highest viscosity on the rheological characterization. Flood tests using the alkali‐polymer solution showed an increase in oil recovery by 30% over water‐flooding when the water‐cut reached 95%, indicating that alkali‐polymer could be more effective in improving sweep efficiency than polymer flood. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Flow improvement of Liaohe extraheavy oil with comb‐type copolymers

Liaohe extraheavy oil is a kind of special crude oil with high paraffin and asphaltene contents and a pour point of up to 60°C. To improve its flowability, comb‐type poly(maleic alkylamide‐co‐α‐octadecene) copolymers (MACs) with various amidation ratios were synthesized and used. Model oils containing paraffin mixtures with the same average carbon number to Liaohe extraheavy oil with and without asphaltene were prepared to explore the effect of the MACs on paraffin crystallization and asphaltene dispersion, respectively. We found that MACs reduced the yield stress, changed the size and shape of the paraffin crystals, and obstructed the paraffin crystallization for both model oils and extraheavy Liaohe oils as observed by rheology, polarizing light microscopy, X‐ray diffraction, and differential scanning calorimetry. The MACs seemed to be an ideal candidate for improving the flowability of Liaohe extraheavy oils. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40082.     

Solution behavior of water‐soluble poly(acrylamide‐co‐sulfobetaine) with intensive antisalt performance as an enhanced oil‐recovery chemical

In the process of oilfield development, salt tolerance is an important property for enhanced oil‐recovery (EOR) chemicals. In this study, we synthesized two acrylamide‐based sulfobetaine copolymers containing 2‐hydroxy‐3‐[(3‐methacrylamidopropyl)dimethylammonio]propane sulfonate (SHPP) or 3‐(4‐acry‐loyl‐1‐methyl‐piperazinio)‐2‐hydroxypropane sulfonate (SHMP). The interactions between these two copolymers and inorganic salts were compared, and the apparent viscosity (η_app) behaviors of copolymer–salt solutions at different shear rates and temperatures were investigated. We found that the η_app of PAPP and PAMP showed intensive antisalt performance, exhibiting an excellent antipolyelectrolyte effect. The η_app retention value of 30,000 mg/L PAMP in brine was 86.47 mPa s at 510 s^?1, and when the temperature was increased to 90 °C, it was 99.73 mPa s; this was better than that of PAPP under the same conditions. Therefore, PAMP was more applicable as an EOR chemical that have outstanding salt tolerance and temperature resistance. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46235