十四烷基三甲基溴化铵蠕虫状胶束的形成及其线性黏弹性

以阳离子表面活性剂十四烷基三甲基溴化铵(TTAB)溶液作为反应主剂,油酸钠(NaOA)溶液作为反应助剂,制备得到了TTAB/NaOA蠕虫状胶束,并研究了表面活性剂摩尔比、主剂质量分数对蠕虫状胶束线性黏弹性的影响。结果表明,当主剂TTAB与助剂NaOA的摩尔比为2.6∶1～4.6∶1,TTAB质量分数在7%～16%之间时,溶液中均有蠕虫状胶束形成。当主剂TTAB与助剂NaOA的摩尔比为4.2∶1,TTAB质量分数为14%时,零剪切黏度可达到最大值即为η₀=15 324 mPa·s,且溶液体系的平台模量G₀和弛豫时间τ_R也达到最大值,此时溶液体系中蠕虫状胶束长度最长,网络结构最为紧密,并呈现出良好的线性黏弹性。由上述溶液体系的实际Cole-Cole图表明本文探讨研究的蠕虫状胶束体系是符合麦克斯韦模型的线性黏弹性流体。     

蠕虫状胶束溶液组成对其黏弹性影响

用阳离子表面活性剂十八烷基三甲基溴化铵(STAB)作为主剂,水杨酸钠(NaSal)/碳酸钠(Na_2CO_3)、油酸钠(NaOA)作为助剂,制备蠕虫状胶束溶液,研究组分摩尔比及助剂种类对蠕虫状胶束流变特性的影响。结果表明,溶液总质量分数为3.3%,STAB与助剂摩尔比R在2.2~2.6时,两个体系均形成了蠕虫状胶束。助剂为NaSal/Na_2CO_3,R=2.4时体系形成的胶束最长;助剂为NaOA,R=2.6时体系形成的胶束最长,数目最多。摩尔比相同时,STAB/NaOA溶液黏弹性更好。由溶液的实际模量所得Cole-Cole图在低频及中频时为半圆形,说明所制备的2种溶液均为符合麦克斯韦模型的黏弹性流体。     

pH对油酸钠/盐酸三乙胺蠕虫状胶束流变性质的影响

用流变学方法研究了pH对油酸钠/盐酸三乙胺(NaOA/Et3NHCl)蠕虫状胶束溶液流变性质的影响。通过稳态剪切和动态流变实验发现,30℃时,NaOA(0.12 mol/L)/Et3NHCl(0.2 mol/L)溶液在pH=8.20~9.40循环变化时,pH对溶液黏度的改变具有"开关"效应,可实现黏度在3~27 649 mPa·s时反复变化3次以上。体系在pH=8.55~9.02时为蠕虫状胶束,其流变行为符合Maxwell模型。这种溶液流变性对pH的响应行为是由于pH对反离子Et3NH+与NaOA的相互作用影响而产生的。当pH降低时,反离子Et3NH+的离子势增大,导致胶束表面电荷密度降低,蠕虫状胶束进一步增长。当pH=8.64,胶束因相互吸引而析出。而在初始条件下,升高pH=9.40,反离子Et3NH+从胶束中解吸出来,蠕虫状胶束受到破坏。     

十六烷基三甲基溴化铵/油酸钠混合体系蠕虫状胶束流变性研究

阴、阳离子表面活性剂之间强烈的相互作用利于形成自由弯曲的蠕虫状胶束。本文利用阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)和阴离子表面活性剂油酸钠(NaO A)制备了CTAB/NaO A蠕虫状胶束,研究了两表面活性剂的混合比和表面活性剂总浓度的变化对蠕虫状胶束体系稳态流变性及动态黏弹性的影响。结果表明,蠕虫状胶束在剪切过程中的解缠、拟网状结构的破坏以及最终沿剪切速度方向取向等是蠕虫状胶束产生剪切稀释特性的原因。两表面活性剂的混合比和表面活性剂总浓度的变化导致表面活性剂之间的静电作用、疏水作用发生较大的变化,最终引起体系内部表面活性剂聚集体形态的差异。体系内蠕虫状胶束长度、体系结构复杂程度、蠕虫状胶束形成的网络结构的致密度等都影响着体系的流变行为。在混合比R=3.6、总浓度cT=0.24 mol/L时,体系中蠕虫状胶束最长,网络结构最为紧密,体系的零剪切黏度达到最大值。表面活性剂浓度一定时,混合比的提高有助于蠕虫状胶束的定向生长,弛豫时间τR和储能模量高频区平台模量G0提高,R=3.6时两者皆达到极大值,此后由于蠕虫状胶束的分枝化及(或)胶束破裂导致τR及G0下降。在表面活性剂混合比一定(R=3.6)时,表面活性剂浓度的提高利于蠕虫状胶束的增长或者分枝化,增加了胶束网络结构缠绕(融合)点的密度,导致G0逐渐增大。Cole-Cole图证实本文研究的蠕虫状胶束体系是符合Maxwell模型的线性黏弹性流体。     

简述离子表面活性剂构筑蠕虫状胶束的研究现状

粘弹性蠕虫状胶束具有特殊的微观结构,其流变性能在不同领域具有重要的应用。本文介绍了表面活性剂构筑的蠕虫状胶束的结构特点、应用及研究现状。传统离子表面活性剂构筑蠕虫状胶束通常需要一些外加作用,Gemini表面活性剂因其结构优势,可以自身形成蠕虫状胶束。     

致密油藏CO2驱响应性防窜体系的制备及性能

以3-二甲胺基丙胺和油酸为主剂制备具有叔胺结构的CO₂响应性单体N,N-二甲基油酸酰胺丙基叔胺(DOAPA),将其与有机反离子互配构建具有CO₂响应性的蠕虫状胶束(CO₂-TWMS)。通过体系与CO₂接触前后的电导率、化学结构和微观形貌变化表征体系的响应性,结合体系表面活性变化及致密基质/裂缝双重介质CO₂驱替与CO₂-TWMS防窜过程中的压力和采收率变化揭示CO₂-TWMS防窜性能与机制。实验结果表明,当反离子为对甲苯磺酸钠,与DOAPA的摩尔比为1:1时,CO₂-TWMS体系的黏度最大。CO₂和N₂能够刺激体系电导率在0.9ms/cm和1.95ms/cm之间可逆变化、诱导微观形貌在蠕虫状胶束和球形胶束间转换。此外,CO₂能够将体系临界胶束浓度从1mmol/L降低至0.25mmol/L,最低表面张力从30.2mN/m降低至29.1mN/m,体系在气液界面的吸附效率和效能增强,有利于胶束的形成。在致密基质-裂缝双重介质中,CO₂诱导蠕虫状胶束形成,增大驱替过程中的压差,扩大CO₂驱替波及效率,采收率提高22.6%。     

CO2/N2-紫外光双重响应蠕虫状胶束制备

通过N,N-二甲基十二烷基胺（DMA）、十六烷基三甲基溴化铵（CTAB）以及肉桂酸钠（CA）构建了一种具有CO₂/N₂-紫外光双重响应的蠕虫状胶束体系。研究发现DMA、CTAB、CA组成的体系黏度较低,不能形成蠕虫状胶束,向上述体系中引入CO₂后会引起DMA的质子化,从而导致表面活性剂分子在体系中的排列方式发生改变并形成蠕虫状胶束。在通入N₂后蠕虫状胶束会可逆地转变为球状胶束。进一步研究发现,由于CA可以在紫外光的照射下实现反式结构与顺式结构的转变,对已经形成的蠕虫状胶束体系照射紫外光也可以形成黏度较低的球状胶束。     

致密油藏CO2驱响应性防气窜体系的制备及性能

以3-二甲胺基丙胺(NNDP)和油酸为原料,制备了具有叔胺结构的CO₂响应性单体N,N-二甲基油酸酰胺丙基叔胺(DOAPA),将其与阴离子表面活性剂对甲苯磺酸钠(SPTS)复配,构建了具有CO₂响应性的蠕虫状胶束(CO₂-TWMS)。通过考察CO₂-TWMS与CO₂接触前后的电导率、化学结构和微观形貌变化表征了体系的响应性,结合其表面活性变化及致密基质/裂缝双重介质CO₂驱替与CO₂-TWMS防气窜过程中的压力和采收率变化,揭示了CO₂-TWMS防气窜性能与机制。结果表明,当n(SPTS)∶n(DOAPA)=1∶1时,CO₂-TWMS的黏度最大(4125m Pa·s)。CO₂和N₂能够刺激CO₂-TWMS电导率在0.90～1.95mS/cm之间可逆变化,诱导微观形貌在蠕虫状胶束和球形胶束间转换。此外,CO₂     

聚/表二元体系注入时机对驱油效果影响研究

随着化学驱技术的进一步发展,聚驱后仍有大量的剩余油存在地下,需要进一步对剩余油进行挖潜。聚/表二元驱作为聚驱后进一步提高采收率的方法,能有效的提高驱油效果。对于聚驱后储层非均质性更加严重的储层,聚/表二元驱能够进一步扩大波及体积,提高洗油效率,进而达到提高采收率的目的。以室内物理模拟为技术手段,分析了不同聚/表二元注入段塞尺寸对岩心驱油效果的影响。     

聚驱后颗粒泡沫复合体系驱油效果

在优选出可与大庆油水形成超低界面张力的表面活性剂的基础上,开展了聚驱后不同颗粒+二元泡沫驱室内三层非均质驱油实验,优选出最佳体系配方指导现场试验。结果表明：聚驱后采用0.1%PPG颗粒+泡沫驱驱油效果最佳、注入压力最大,最佳体系配方条件下,聚驱后采收率提高值为13.4%。     

Electrostatic Effect on Synergism of Wormlike Micelles and Hydrophobically Modified Polyacrylic Acid

The electrostatic effects on the synergism between wormlike micelles and hydrophobically modified polyacrylic acid (HMPA) have been investigated by rheological measurements and dissipative particle dynamics molecular simulation (DPD). Both cationic surfactants, cetyltrimethylammonium bromide (CTAB), and anionic surfactant, sodium oleate (NaOA), were employed to construct wormlike micelles, and the influences of both simple salts, NaBr or NaAc, and hydrophobic salts, sodium benzoate (NaBen) and benzyltrimethyl ammonium bromide (BTAB), were discussed. The synergistic effects vary with the headgroup charge and the counterions property of surfactants. For the NaOA system, the obvious viscosity maximum was observed only at low NaAc content, while a monotonous viscosity increase appeared at a high content of BTAB. However, the optimal synergism can be only observed in the presence of concentrated NaBen in CTAB system. DPD molecular simulation provides a support and favorable illustration for the synergism mechanism. It suggests that not only the hydrophobic interaction but also the electrostatic interaction has an important impact on the synergism between ionic wormlike micelles and HMPA.     

Contrasting the Effects of Hydrophobicity and Counterion Size on Anionic Wormlike Micelle Growth

Rheological measurements were performed to understand the effect of benzyltrimethyl ammonium bromide (BTAB) and NaBr on the growth of wormlike micelles formed by sodium oleate (NaOA). Both salts can make the micellar solution viscoelastic, and the rheological responses verify the formation of wormlike micelles. The viscoelastic solution follows the Maxwell model of a single stress relaxation mode in the low-frequency region. In comparison, the BTAB system exhibits stronger viscoelasticity than the NaBr system at constant salt concentration, but the critical overlapping concentration shows no significant difference; less BTAB can induce the solution to be more viscous than NaBr, but the viscosity maximum of the BTAB system is remarkably lower than that of NaBr at fixed NaOA content. The puzzling result is attributed to the effect of the composition on the packing parameter. In addition, it is shown that the zero-shear viscosity of the two salt systems decreases upon heating, following the Arrhenius mode well.     

Rheological behavior of mixed system of ionic liquid [C8mim]Br and sodium oleate in water

We report on the rheological behavior of wormlike micelles constructed by ionic liquid surfactant [C₈mim]Br (1-octyl-3-methylimidazolium bromide) and anionic surfactant sodium oleate (NaOA) in aqueous solution. The effects of surfactant composition, total surfactant concentration, added salts, and temperature were investigated. The prevailing surfactant effect at lower concentration and the leading cosolvent effect at higher concentration of [C₈mim]Br may be the main reasons for appearance of well-established maximum in key rheological parameters with variation of surfactant composition and total surfactant concentration. The Cole-Cole plots demonstrate that the systems (total surfactant concentration falls within 0.17–0.35 mol·L^-1 and molar ratio 0.33≤R≤0.50) fit the Maxwell’s mechanical model as linear viscoelastic fluid. The addition of NaBr or sodium salicylate decreases significantly the viscosity and the relaxation time of the wormlike micelle solution but cannot change the value of plateau modulus G₀. The present system has low rheological tolerance to temperature. The increase of temperature decreases the average contour length and viscosity of wormlike micelles and thus strengthens the relaxation progress of diffusion and weakens the relaxation progress of reptation. Increasing the temperature also decreases the value of plateau modulus G₀ and shifts the minimum value of the loss modulus G^″_min to higher frequencies.     

聚驱后强弱碱三元体系极限驱油效果实验研究

随着大庆油田主力油层开发进入高含水阶段,急需聚合物驱后提高采收率接续技术方法。本文针对聚合物驱进入高含水阶段后进行三元驱的可行性展开了研究,利用达到超低界面张力条件的三元体系,模拟聚合物驱达到极限驱油效率后,开展三元体系极限驱油效果对比研究。结果表明:在聚合物驱达到极限采收率后,开展三元体系驱油能够进一步提高驱油效率,当弱碱三元体系中碱浓度较低时,聚驱后三元驱的采收率增加值较高,阶段极限采收率可达32.97%;当强碱三元体系中强碱浓度较高时极限采收率可达30.29%。在体系其他组成相同的条件下,基于强碱三元体系对注入系统和油层伤害较严重的问题,建议采用弱碱三元体系开展驱油生产。     

水相和特殊介质中有序聚集体的结构、性质和应用(Ⅱ)——表面活性剂蠕虫状胶束

综述了近来关于表面活性剂蠕虫状胶束相态、平衡状态和动态的理论和实验结果以及应用冷冻蚀刻电镜照片直接观察到其结构。在一定条件下,表面活性剂在溶液中能可逆地缔合成为一种长的、有柔性的、甚至网状的蠕虫状胶束。它们具有类似柔软的高聚物溶液的线性黏弹性质,然而蠕虫状胶束经历裂解和再组合过程而表现复杂的流变性。最后介绍了蠕虫状胶束在油田、减阻剂和日用化工等方面的应用。     

海上油藏变浓度聚合物驱剖面控制实验与应用

针对渤海强非均质、中高粘油藏聚驱过程中低渗层吸液剖面初期改善,之后又变差的现象,首先通过岩心驱替实验分析了聚合物溶液浓度对吸液剖面的影响规律;然后测试了高浓-低浓聚合物驱交替注入方式在非均质油藏中的驱油效果。结果表明:通过在聚驱早、中期阶段增加聚合物溶液的浓度,能够对高渗层有效的封堵,增加注入压力、显著改善低渗层的吸液剖面。结合油田实例研究表明:在现场条件允许情况下,相同聚合物用量,采用高浓-低浓段塞聚合物驱方式相比恒浓度聚驱,能够提高低渗层动用程度,增加总体采收率约1%。     

Synergistic Behavior and Microstructure Transition in Mixture of Zwitterionic Surfactant,Anionic Surfactant,and Salts in Sorbitol/H<Subscript>2</Subscript>O Solvent: 1. Effect of Surfactant Compositions

The phase behavior and rheological properties of a multi-component system, made of a zwitterionic surfactant cocoamidopropyl betaine (CAPB), an anionic surfactant sodium lauryl sulfate (SLSS), and mixed salts (tetrasodium pyrophosphate, sodium acid pyrophosphate, sacharrin, and sodium fluoride) in sorbitol/H₂O mixed solvent at different mass fraction of SLSS (X _SLSS) were systematically investigated by steady and dynamic rheology, dynamic light scattering, and diffusion ordered spectroscopy (DOSY). When fixing the salt concentration and the mass ratio of sorbitol in mixed solvent (R), the zero-shear viscosity increases first and then decreases showing a maximum with increasing X _SLSS, resulting from the formation and entanglement of wormlike micelles. Especially when X _SLSS is between 0.33 and 0.80, the mixture is dominated by entangled wormlike micelles coexisting with small micelles and separated wormlike micelles, and shows high viscoelasticity. The maximum of the zero-shear viscosity is ca. 5 orders of magnitude larger than that of sorbitol/H₂O mixed solvent or the CAPB/SLSS aqueous solution. The characteristic structural parameters for the micellar solutions at different X _SLSS are also estimated from further analysis of the rheological results, and indicate the stronger network structures of the wormlike micelles are formed in our systems compared with the wormlike micelles formed by a traditional zwitterionic/anionic surfactant aqueous solutions. The great improvements of rheological properties are attributed to the strong screening effects of the mixed salts and the strong solvophobic effect of sorbitol on the electrostatic and hydrophobic interaction between the CAPB and SLSS molecules. The present work has improved our understanding about the aggregation behavior of zwitterionic/anionic mixed surfactants with salts in less polar solvent/H₂O mixture, which would be of widely practical importance to optimize the formulation of products for personal care and household cleaning.     

阳离子双子表面活性剂C18-4- C18•2Br的流变性

对阳离子双子表面活性剂四亚甲基-1,2-双(十八烷基二甲基烷基溴化铵)(C18-4-C18.2Br)的流变特性进行了研究,考察了表面活性剂质量分数、水杨酸钠质量分数及温度对表面活性剂溶液黏度和黏弹性的影响。C18-4-C18.2Br溶液的黏度随着质量分数的增加而增加。随着水杨酸钠质量分数的增加,C18-4-C18.2Br溶液的黏度和黏弹性出现先增加后下降的过程。温度对C18-4-C18.2Br溶液的黏度有较大影响,水杨酸钠的加入可明显提高C18-4-C18.2Br溶液的抗温性。TEM结果表明,适量的水杨酸钠能够促进C18-4-C18.2Br胶束从球形向蠕虫状转变,过量的水杨酸钠又会使蠕虫状胶束向囊泡转变。     

Enhancing Oil Recovery by Low Concentration of Alkylaryl Sulfonate Surfactant without Ultralow Interfacial Tension

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 recovery efficiency can be obtained from low concentration surfactant flooding without forming microemulsions, and the principle behind has not been clearly unraveled yet. Here the solubilization of paraffin oil by the micelles formed with a commercial enhanced oil recovery surfactant, raw naphthenic arylsulfonates (NAS), was investigated using ultraviolet-visible (UV–Vis) spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM). It is found that paraffin oil can be well solubilized inside the NAS micelles, and mainly localized in the hydrophobic core of the micelles. The solubilization capacity of NAS micelles increases with increasing its concentration, and the size of micelles increases, but morphology of the micelles remains spherical with increasing the amount of paraffin oil, along with an appearance transition from transparent to opaque until the maximum solubilization capacity is reached. Core flooding results with crude oil indicate that in the presence of 0.24 wt.% polymer, addition of 0.1, 0.2, 0.5, and 1.0 wt.% NAS can get oil recovery factor of 24.1%, 27.0%, 30.5%, and 38.3%, which increases linearly with increasing NAS concentration though with the interfacial tension values only in the magnitude of 10⁻² mN m⁻¹ level. These findings prove preliminarily micellar solubilization can help increasing oil recovery efficiency even without ultralow IFT.