Yujun Feng

Yujun Feng
Sichuan University | SCU · State Key Laboratory of Polymer Materials Engineering

PhD, Professor

About

228
Publications
39,044
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
7,294
Citations
Citations since 2016
103 Research Items
5595 Citations
201620172018201920202021202202004006008001,000
201620172018201920202021202202004006008001,000
201620172018201920202021202202004006008001,000
201620172018201920202021202202004006008001,000
Introduction
Mainly focus on smart soft matters including polymers, gels and wormlike micelles, and their applications in the procedures of oil and gas production, including tertiary oil recovery, oilwell acidizing, oilwell fracturing...
Additional affiliations
September 2012 - present
Sichuan University
Position
  • Professor
September 2012 - present
Sichuan University
Position
  • Professor
Description
  • Give the course "Soft Matter" to the master students.
January 2004 - August 2012
Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences
Position
  • Professor

Publications

Publications (228)
Article
Generally, the solution viscosity of wormlike micelles (WLMS) assembled from common surfactants decreases upon increasing temperature, following the Arrhenius law. However, abnormal thermo-thickening behavior has been repeatedly observed for WLMs...
Article
Full-text available
As compared to China’s overall oil reserves, the reserve share of offshore oilfields is rather significant. However, offshore oilfield circumstances for enhanced oil recovery (EOR) include not just severe temperatures and salinity, but also restricted space on offshore platforms. This harsh oil production environment requires polymers with relative...
Article
Hypothesis It is generally believed that the improved efficiency of surfactant enhanced oil recovery (EOR) comes from ultra-low interfacial tension (IFT) between oil and surfactant solution owing to the formation of middle-phase microemulsion. However, hindered visibility in underground porous media prevents direct observation of in situ generation...
Article
Understanding the evolution process including foaming, stabilization and ageing of CO2 aqueous foams in high-temperature, high-pressure (HTHP) environments is crucial for their rational use. However, most studies have been conducted through macroscopic observation, leading to inadequate insight into their intrinsic mechanisms. Herein we attempt to...
Article
Full-text available
Nanohybrid materials can significantly inhibit wax deposition and improve the fluidity of crude oil. However, the mechanisms behind wax resolving, crystal modification, and flow improving are still unclear owing to the complexity of crude oil. Here, we compared the effect of ethylene vinyl acetate (EVA) and nanohybrids composed of EVA and SiO2 nano...
Article
Full-text available
Water-soluble polymers as drag reducers have been widely utilized in slick-water for fracturing shale oil and gas reservoirs. However, the low viscosity characteristics, high operating costs, and freshwater consumption of conventional friction reducers limit their practical use in deeper oil and gas reservoirs. Therefore, a high viscosity water-sol...
Article
Full-text available
Water-soluble polymers, mainly partially hydrolyzed polyacrylamide (HPAM), have been used in the enhanced oil recovery (EOR) process. However, the poor salt tolerance, weak thermal stability and unsatisfactory injectivity impede its use in low-permeability hostile oil reservoirs. Here, we examined the adaptivity of a thermoviscosifying polymer (TVP...
Article
Polymer-based in situ cross-linked gels have been widely used in improving the oil recovery process; however, the insufficient and uncontrollable gelation time still deteriorates the successful in-depth water shutoff and conformance control for oil reservoirs due to the short and uncertain moving distance underground. Herein, we report weak gels fo...
Article
Reducing the oil-water interfacial tension (IFT) to ultra-low is believed the primary mechanism for surfactant-based enhanced oil recovery (EOR) process. However, field trials have shown that low concentration surfactant flooding can also improve oil recovery without ultra-low IFT. To clarify the mechanism behind, the currently-used surfactant, nap...
Article
Full-text available
The increasing energy demand has prompted engineers to explore deeper wells where rich oil and gas reserves exist. However, the high-temperature and high-salt conditions have impeded the further application of traditional water-based fracturing fluids in such reservoirs. Therefore, it is urgent to develop fracturing fluids that are suitable for suc...
Article
In China, powders of partially hydrolyzed polyacrylamide (P-HPAM) have been extensively used in chemically enhanced oil recovery (cEOR) processes. However, the relatively longer dissolution time of P-HPAM and high investment in surface facilities diminish the profit. Here, we compared the properties between P-HPAM and emulsion HPAM (E-HPAM) with si...
Article
Full-text available
Wormlike micelles (WLMs) formed by different types of ultra-long-chain surfactants have been well studied except for nonionic ones. Here in this paper, a series of ultra-long-chain nonionic surfactants UCn-350 (n = 18, 22, 24) were synthesized by esterification, and their molecule structures were identified using 1H-NMR, 13C NMR, FT-IR, and GPC. Th...
Article
Polymer or polymer gels have been widely used to control excessive water during oil production by homogenizing injection profile and reducing water cut in the produced fluids. However, the gels used are generally unable to selectively minimize water production, and face the challenge of syneresis of gels under high temperature and high salinity env...
Article
Polytetrafluoroethylene (PTFE) is a kind of fluoropolymer with many critical applications. Nonionic surfactant stabilized concentrated PTFE aqueous dispersions are widely used to prepare corresponding products via dipping, spraying, spinning, or film casting, as these surfactants exert a negligible effect on the properties of the products. Although...
Article
Full-text available
Upon stimulus by CO2, CO2-switchable viscoelastic fluids experience a deliberate transition between non-viscous and highly viscous solution states. Despite attracting considerable recent attention, most such fluids have not been applied at a large- scale due to their high costs and/or complex synthesis processes. Here, we report the development of...
Chapter
It is well recognized that ultra-low interfacial tension (IFT) from formation of middle-phase microemulsion is a must in surfactant-based EOR process. However, high concentration of surfactant or surfactant mixtures is generally needed, and it remains unknown how surfactant micelles evolve when they contact oil in porous media. More importantly, fe...
Article
Water-alternating-CO2 gas (WAG) flooding is a common technique to enhance oil recovery via improving CO2 sweep efficiency, but serious gas channeling may still occur, especially in reservoirs with strong heterogeneity, due to a poor blocking capacity of aqueous slugs to the “channeling” pathway induced by their low viscosity. Herein, a copolymer wh...
Article
Methylcellulose (MC) has received considerable attention because of its thermogelation behavior in aqueous solutions upon heating; however, the accompanied macro-phase separation results in demixing and detriment of thickening power. To alleviate this drawback, a novel family of hydrophilically modified methylcelluloses (HMMCs) was prepared by intr...
Article
Full-text available
As a typical water‐soluble polymer, ultra‐high molecular weight (UHMW) partially hydrolyzed polyacrylamide (HPAM) has been widely used in various industries as thickeners or rheology modifiers. However, precise determination of its critical physical parameters such as molecular weight, radius of gyration (Rg) and hydrodynamic radius (Rh) were less...
Article
Bioinspired honeycomb-like porous films with switchable properties have drawn much attention recently owing to their potential application in scenarios in which the conversion between two opposite properties is required. Herein, the CO2-gas-triggered ON/OFF switching wettability of biocompatible polylactic acid (PLA) honeycomb porous films is fabri...
Article
While polymer flooding represents an effective chemically enhanced oil recovery (EOR) process, the poor thermal stability and weak salt tolerance of commonly used partially hydrolyzed polyacrylamide (HPAM) hindered such a technique to be used in high–temperature and high–salinity (HTHS) oil reservoirs. Here we examined the possibility to use two ne...
Article
Full-text available
Surfactant flooding plays a critical role in chemically enhanced oil recovery over the last half century, with the widely accepted mechanism of ultralow interfacial tension (IFT) by forming middle‐phase microemulsions with high concentration of a lead surfactant and a cosurfactant. However, it is found practically from field trials that high oil re...
Article
The primary mechanism of surfactant enhanced oil recovery (EOR) has always been ascribed to ultralow interfacial tension (IFT) between oil and dispalcing fluid by forming middle-phase microemulsion. However, it is found in field trials that oil can be largely produced by low concentration surfactant flooding without producing microemulsion. Herein,...
Article
Full-text available
Inter-salt shale oil reservoirs located between two salt layers are always accompanied by high temperature and high salin-ity. However, the present commonly used water-soluble polymers in fracturing fluids suffer from poor tolerance to high temperature and high salinity. Thermoviscosifying polymers (TVP) whose aqueous solution shows viscosity incre...
Article
Full-text available
Smart fluids with tunable rheological properties show a wide range of applications in various areas, so they have attracted intense interest. Recently, the viscoelastic fluids with tunable rheological properties, particularly the CO2-triggered smart fluids, have become a popular topic because such reversible change in viscoelasticity conferring the...
Article
Water-soluble polymers have been used as drag reducer in slick-water hydrofracking for unconventional hydrocarbons, however, the fatal “thermothinning” behavior and weak salt tolerance significantly impedes their practical use in more hostile environment. To alleviate these issues, here we present the first attempt to use a polyether-based thermovi...
Article
Hypothesis It is well recognized that crude oil could be emulsified during surfactant flooding process, and recently such an in-situ emulsification was found practically helpful for enhanced oil recovery (EOR). However, no direct proofs are reported yet to unravel how emulsion is formed in porous media and how important to increasing oil recovery f...
Article
Polytetrafluoroethylene (PTFE) has attracted significant interest from both industry and academia owing to its remarkable properties such as wear and corrosion resistance, low surface energy and low dielectric constant. High stability and high solid content (~60%) are primary criteria for PTFE aqueous dispersions toward preparing various end-use ar...
Article
High-strength hydrogels with injectable ability provide possibility of in vivo delivery in a minimally invasive way, but conventional tough hydrogels with excellent mechanical properties are difficult to be injected duo to their robust network structures. Here, “smart” hydrogels were synthesized by a simple one-pot strategy through the synergistic...
Article
Over the last decade, stimuli-responsive microemulsions, i.e., those that switch between stable and unstable states in response to certain stimuli, have attracted considerable attention due to their unique properties and potential for diverse applications. Herein, we highlight the recent advances in the development of microemulsions responsive to e...
Article
Full-text available
The combination of topology and CO2 switchability could provide new options for amphiphilic copolymers. Cyclic molecules supply novel topologies, and CO2 switching provides stimulus responsiveness. Cyclic poly(2–(diethylamino)ethyl methacrylate)–b–poly(ethylene oxide) and their corresponding block copolymers were prepared from poly(ethylene oxide)...
Article
Hypothesis The CO2-sensitive dispersion/precipitation transition of polymer latexes fabricated based on a responsive emulsifier is a promising way to conveniently acquire bulk polymer materials. Nevertheless, the tedious synthesis procedures for switchable surfactants and the harsh operating requirements for the sensitive latexes constrain the appl...
Article
Thermoviscosifying polymers (TVPs) are a class of promising materials for chemically enhanced oil recovery (EOR) because of their unique viscosity increment with increasing temperature. However, previously-reported TVPs have low molecular weight and relatively long dissolution time. To overcome these problems, we synthesized a novel polyether-based...
Article
Hypothesis: The current mechanism of surfactant enhanced oil recovery (EOR) mainly relies on forming middle-phase microemulsions to get ultra-low oil-water interfacial tension. However, residual oil can also be recovered using low concentration surfactant solutions without microemulsion formation, and the interaction between the surfactant solutio...
Article
Full-text available
Alkylaryl sulfonate is a typical family of surfactants used for chemically enhanced oil recovery (EOR). While it has been widely used in surfactant–polymer flooding at Karamay Oilfield (40 °C, salinity 14,000 mg/L), its aggregation behavior in aqueous solutions and the contribution of aggregation to EOR have not been investigated so far. In this st...
Article
The synthesis of a semicrystalline block copolymer compromising of a hydrophilic poly(acrylic acid) (PAA) pure block and a amphiphilic poly(acrylic acid)-r-poly(octadecyl acrylate) (PAA-r-PODA) random block by nitroxide-mediated polymerization (NMP) is reported. The aggregation behavior of the copolymer in the aqueous medium was studied by Microcal...
Article
Wormlike micelles (WLMs) are long, flexible cylindrical chains formed by the self-assembly of surfactants in semidilute solutions. Scientists have been fascinated by WLMs because of their similarities to polymers, while at the same time, the viscoelastic properties of WLM solutions have made them useful in a variety of industrial applications. To d...
Article
Polyelectrolytes are widely used to thicken hydrofracking fluids due to its good solubility and strong thickening power. However, the poor salt tolerance impedes their application at high salinity. To address this issue, a polyelectrolyte complex is prepared from anionic poly(acrylamide‒co‒acrylic acid‒co‒2-acrylamido-2-methyl-1-propanesulfonic aci...
Article
Considerable success has been achieved in enhanced oil recovery by polymer flooding from high- to medium-permeability reservoirs; however, the poor injectivity and ease of mechanical degradation of the commonly used high-molecular-weight (high-MW) partially hydrolyzed polyacrylamides (HPAM) impede their use in low-permeability reservoirs. To allevi...
Article
Hypothesis Current viscoelastic surfactant (VES) aqueous solutions quickly freeze and thus, lose their viscoelasticity and flowability at subzero temperatures, limiting their practical use in cold environments. Therefore, it is highly desirable to develop cryo-VES fluids with freezing point far below 0 °C. Since addition of alcohol antifreeze great...
Article
CO2 has been widely used in the process of enhanced oil recovery (EOR) over decades. However, the heterogeneity of oil reservoirs renders CO2 to flow preferentially into highly permeable zones, leaving tight areas unswept with oil unrecovered in these areas. While conventional water‐swelling gels were used for blocking the “channeling” path, most o...
Article
Full-text available
The synthetic water-soluble polymer, partially hydrolyzed polyacrylamide (HPAM), has been most widely used for enhanced oil recovery (EOR); however, its poor thermal stability and weak salt tolerance impede further application in high-temperature and high-salinity oil reservoirs. To address such deficiencies, three polysaccharides, xanthan gum, diu...
Article
A unique triple patterned honeycomb film with CO2-driven reversible wettability between hydrophobicity and hydrophilicity is reported in this work. Honeycomb film is prepared by directed self-assembly in “Breath Figure” BF templating of a PolyStyrene-b-Poly(VinylBenzylChloride) PS-b-PVBC block copolymer using a mixed water/ethanol atmosphere. Three...
Article
Honeycomb-patterned porous films with good surface wettability have great potential applications in various areas. However, hydrophilic honeycomb films are difficult to obtain using the direct self-assembly of pure (co)polymers. Thus, additional and special treatments are required to improve film wettability, which makes the procedure complicated a...
Article
Full-text available
Inter-salt shale oil reservoirs located between two salt layers are always accompanied by high temperature and high salinity. However, the present commonly used water-soluble polymers in fracturing fluids suffer from poor tolerance to high temperature and high salinity. Thermoviscosifying polymers (TVP) whose aqueous solution shows viscosity increa...
Article
Full-text available
Correction for ‘Cryogenic wormlike micelles’ by Hongyao Yin et al. , Soft Matter , 2019, 15 , 2511–2516.
Article
Cryogenic wormlike micellar solutions which possess freezing point far below 0 oC while retaining rheological properties similar to those of ordinary wormlike micellar solutions are fabricated from the self-assebmly of...
Article
Full-text available
Foams are widely used to remove liquid loading at the bottom of gas wells to improve natural gas production. However, it becomes ineffective when a gas well contains a large amount of hydrocarbon condensate because oil will rupture the foams. In this work, condensate oil-tolerant foams were developed and stabilized by a mixture of cocamidopropyl hy...
Article
A polymer-surfactant complex is significant in understanding the interactions between amphiphilic molecules and has great potential for use in a vast number of industries. In addition, the stimuli-responsive polymersurfactant complex represents a hot research topic for the colloid community. However, the use of CO2 gas to tune their interaction and...
Article
Full-text available
The addition of salt to a colloid solution ensures that emulsions can be easily separated into two phases and that polymer latexes can be coagulated. The switchable stability of emulsions and polymer latexes would improve the properties for their current applications. A switchable process of salt addition can be achieved using CO2 and switchable wa...
Article
Adsorbents that are capable of controllable pollutants adsorption and releasing without secondary pollution are attractive in water treatment. Here, we propose eco-friendly CO2 as a trigger to switch the charge states of giant microgels consisted of hydrophilic acrylamide (AM) and hydrophobic 2-(diethylamino)-ethyl methacrylate (DEA), and demonstra...
Article
Smart soft materials comprising stimuli-responsive micelles represent an innovative imitation of materials found in nature. These morphologically multicolored assemblies manifest versatile compliances in response to multiple triggers from environmental changes. Among these, asymmetric amphiphilic block copolymers afford elegant morphological struct...
Article
Thermoviscosifying polymers are attractive for enhancing oil recovery owing to their exceptional thickening power as temperature increases. However, the polymers reported to date show inadequacies including obligatory high polymer concentration to get the thermothickening ability because of their low molecular weight (MW), and inconvenient post‐tre...
Article
Hypothesis: The effective separation and recovery of oils from water is important for the protections of ecosystems and the environment. Polymeric porous monoliths have been demonstrated as attractive absorbents for oil/water separation. However, the recyclability was mainly realized by squeezing, combustion, or centrifugation, which may restrict...
Article
Styrene–isoprene–styrene triblock copolymers (SIS) are representative thermoplastic elastomers possessing both elastomeric and thermoplastic feature. SIS have been used in self-healing cement for natural gas wells, but the mechanism behind the application was not unravelled. We hypothesise such self-repairing function should be associated with the...