An Experimental Study on Alkaline/Surfactant/Polymer Flooding Systems Using Natural Mixed Carboxylate

Orthogonal-test-design method has been used to determine the optimal formula by phase behavior and interfacial tension studies, respectively. The effect of each component of two alkaline/surfactant/polymer flooding systems on interfacial tension is discussed, in which a low-price natural mixed carboxylate (SDC) is used as the major surfactant. The results indicate that the optimal composition is SDC (0.5%), alkaline NaHCO3/Na2CO3 with mass ratio of 1 (1.0%), and hydrolyzed polyacrylamide(0.1%). In the coreflood experiment, their oil recovery is increased by about 25.2% and 26.8% original oil in place, respectively.

Stabilization of nickel nanoparticle suspensions with the aid of polymer and surfactant: static bottle tests and dynamic micromodel flow tests

Nickel nanoparticles can work as catalyst for the aquathermolysis reactions between water and heavy oil.A homogeneous and stable suspension is needed to carry the nickel nanoparticles into deeper reservoirs.This study conducts a detailed investigation on how to achieve stabilized nickel nanoparticle suspensions with the use of surfactant and polymer.To stabilize the nickel nanoparticle suspension,three surfactants including sodium dodecyl sulfate,cationic surfactant cetyltrimethylammonium bromide and polyoxyalkalene amine derivative(Hypermer) along with xanthan gum polymer were introduced into the nickel nanoparticle suspension.Static stability tests and zeta potential measurements were conducted to determine the polymer/surfactant recipes yielding the most stable nickel nanoparticle suspensions.Dynamic micromodel flow tests were also conducted on three suspensions to reveal how the nickel nanoparticles would travel and distribute in porous media.Test results showed that when the injection was initiated,most nickel nanoparticles were able to pass through the gaps between the sand grains and produced in the outlet of the micromodel;only a small number of the nickel nanoparticles were attached to the grain surface.A higher nickel concentration in the suspension may lead to agglomeration of nickel nanoparticles in porous media,while a lower concentration can mitigate this agglomeration.Moreover,clusters tended to form when the nickel nanoparticle suspension carried an electrical charge opposite to that of the porous media.Follow-up waterflood was initiated after the nanofluid injection.It was found that the waterflood could not flush away the nanoparticles that were remaining in the micromodel.

Effects of pore structure on surfactant/polymer floodingbased enhanced oil recovery in conglomerate reservoirs

To understand the displacement characteristics and remaining oil displacement process by the surfactant/polymer(SP) flooding in cores with different pore structures, the effects of pore structure on the enhanced oil recovery of SP flooding was investigated at the pore, core and field scales through conducting experiments on natural core samples with three typical types of pore structures. First, the in-situ nuclear magnetic resonance core flooding test was carried out to capture the remaining oil variation features in the water flooding and SP flooding through these three types of cores. Subsequently, at the core scale, displacement characteristics and performances of water flooding and SP flooding in these three types of cores were evaluated based on the full-size core flooding tests. Finally, at the field scale, production characteristics of SP flooding in the bimodal sandstone reservoir and multimodal conglomerate reservoir were compared using the actual field production data. The results show: as the pore structure gets more and more complex, the water flooding performance gets poorer, but the incremental recovery factor by SP flooding gets higher;the SP flooding can enhance the producing degree of oil in 1-3 μm pores in the unimodal and bimodal core samples, while it produces largely oil in medium and large pores more than 3 μm in pore radius in the multimodal core sample. The core flooding test using full-size core sample demonstrates that the injection of SP solution can significantly raise up the displacement pressure of the multimodal core sample, and greatly enhance recovery factor by emulsifying the remaining oil and enlarging swept volume. Compared with the sandstone reservoir, the multimodal conglomerate reservoir is more prone to channeling. With proper profile control treatments to efficiently enlarge the microscopic and macroscopic swept volumes, SP flooding in the conglomerate reservoir can contribute to lower water cuts and longer effective durations.

Synthesis and Properties of the Polymeric Surfactant Based on Maleamic Acid and Styrene

An alternative polymeric surfactant P（M3/St） was synthesized by solution polymerization of maleamic acid as hydrophilic monomer and styrene as hydrophobic monomer. Some factors that affect the yield and properties of the polymeric surfactant were investigated systemically. The surface tension of the polymeric surfactant reaches 37-38 mN/m. It is proved that the polymeric surfactant shows very good surface activity and emulsifying ability. The TG analysis shows that the temperature of the thermal degradation can reach 314.4 ℃. It will be used as a new type of polymeric surfactant.

Enhancement of Formation of Polar Microenvironment in Polymer by Compressed CO_(2)

The copolymer (EO)22(PO)52(EO)22 in p-xylene can solubilize much more water in the presence of compressed CO2 than the case without CO2.

Research on Influence Factors of Surfactivity of Polyester Polyether Block Copolymer

Polyester polyether block copolymer （PPBC） was synthesized by ester-exchange and polycondensation reactions using dimethyl terephthalate （DMT）, ethylene glycol （EG） and polyethylene glycol （PEG） as monomer. The effects of PEG molecular weight, mol ratio of DMT to PEG （nDMT/nPEG）, temperature and time of polycondensation reaction and vacuum degree in the reaction system on the surface tension and critical micelle concentration （CMC） of PPBC aqueous solution were studied. It was found that both the molecular weight and the concentration of PEG can affect PPBC＇s surface activity obviously, and the optimum synthesis condition of PPBC used as surfactant is as follows： PEG molecular weight is 1 500, tool ratio of DMT to PEG is 3, temperature and time of polycondensation reaction is 260℃ × 1 h, vacuum degree of condensation reaction is 0.03-0.05 MPa. It was proved by surface tension measurement of PPBC aqueous solution that the PPBC synthesized in this condition is a good surfactant with excellent surfactivity.

XPS Study on Water-Soluble Polymer Surfactant Film

By means of changing the detection angle, the molecular conformation of a new type of polymer surfactant, acrylamide-poly(oxyethykene alkyl ether)acrylate-anionic monomer random copolymer, was studied by x-ray photoelectron spectroscopy(XPS) in detail.

Synthesis of Silver Nanoparticle and Its Morphological Control

Silver nanoparticles with different morphologies were prepared in AgNO3 aqueous solution using nanocarbon as template medium and polymer surfactant as protecting agent in an ultrasonic field.The polymer surfactant polyvinylpyrrolidone(PVP)was self-prepared and used directly in aqueous solution form.The molecular weight of PVP was measured by viscosimeter.The crystalline phase,component,size,and morphology of the as-synthesized silver naoparticles were characterized by XRD,TEM,FTIR,and Laser Granularity Instrument.The results indicated that ultrasonic was the key factor to deoxidize Ag+ to be Ago,nanocarbon and polymer surfactants accelerated the deoxidization reaction course and controlled the agglomeration of freshly formed silver nanoparticles,the category of polymer surfactant had decisive effect on the morphology of as-synthesized nanoparticle.Well-defined dendrites silver nanoparticle could be attained when choosing PVP as surfactant in AgNO3 aqueous solution,while regular sphere silver nanoparticle could be synthesized in the presence of polyvinyl alcohol(PVA)surfactant.Moreover,the concentration of AgNO3 and ultrasonic action time also had obvious effect on the morphology of silver nanoparticle,low concentration of AgNO3 and long time of ultrasonic were not in favor of forming dendrite silver.

Influences of spinel type and polymeric surfactants on the size evolution of colloidal magnetic nanocrystals （MFe2O4, M = Fe, Mn）

Two types of polymeric surfactants, PEG300 and PVP40000, were used for the preparation of magnetic ferrite MFe2O4 （M- Mn, Fe） colloidal nanocrystals using a solvothermal reaction method. The effect of spinel type effect on the size evolution of various nanoparticles was investigated. It was found that Fe3O4 nanoparticles exhibited higher crystalinity and size evolution than MnFe2O4 nanoparticles with use of the two surfactants. It is proposed that this observation is due to fewer tendencies of surfactants on the surface of Fe3O4 building blocks nanoparticles than MnFe2O4. Less amounts of surfactant or capping agent on the surface of nanoparticles lead to the higher crystalibity and larger size. It is also suggested that the type of spinel （normal or inverted spinel） plays a key role on the affinity of the polymeric surfactant on the surface of building blocks.

Synthesis and characterization of castor oil-based polymeric surfactants

Dehydrated castor oil was epoxidized using phosphoric acid as a catalyst and acetic acid peroxide as an oxidant to produce epoxidized castor oil(ECO). Ringopening polymerization with stannic chloride was used to produce polymerized ECO(PECO), and sodium hydroxide used to give hydrolyzed PECO(HPECO). The HPECO was characterized by Fourier transform infrared,1H and13 Cnuclear magnetic resonance spectroscopies,gel permeation chromatography, and differential scanning calorimetry. The weight-average molecular weight of soluble PECO and HPECO were 5026 and2274 g$mol^(–1), respectively. PECO and HPECO exhibited glass transition. Through neutralizing the carboxylic acid of HPECO with different counterions, castor oil-based polymeric surfactants(HPECO-M, where M = Na^+, K^+or triethanolamine ion) exhibited high ef ficiency to reduce the surface tension of water. The critical micelle concentration(CMC) values of HPECO-M ranged from0.042 to 0.098 g$L^(–1)and the minimum equilibrium surface tensions at CMC(g cmc) of HPECO-M ranged from 25.6 to30.0 m N$m^(–1). The water-hexadecane interfacial energy was calculated from measured surface tension using harmonic and geometric mean methods. Measured values of water-hexadecane interfacial tension agreed well with those calculated using the harmonic and geometric mean methods.

PMMA-doped CdSe quantum dots as saturable absorber in a Q-switched all-fiber laser

We demonstrate the generation of Q-switched pulses from an ytterbium-doped fiber laser（YDFL） using quantum dot（QD） CdSe as a passive saturable absorber（SA）. The CdSe QD is fabricated by the synthesis of CdO,Se, and manganese acetate and paraffin oil and oleic acid as the solvent and surfactant, respectively. The CdSe QD is then doped into poly-methyl-methacrylate（PMMA） via an emulsion polymerization process. A PMMAhosted CdSe QD thin flake with a homogeneous end surface is then formed and placed between two ferrules and assembled in a YDFL cavity to achieve the Q-switching operation with a repetition rate of 24.45 to 40.50 kHz while varying the pump power from 975 to 1196 mW. The pulse width changes from 6.78 to 3.65 μs with a maximum calculated pulse energy at 0.77 μJ at a pump power of 1101 mW. This work may be the first demonstration of CdSe QD-based Q-switching in an all-fiber configuration that should give proportional insight into semiconductor QD materials in photonics applications.