粘弹性表面活性剂流变性及研究

粘弹性表面活性剂的流变性包括其溶液流变性、低粘度特性、剪切稀释性在油田开发等许多方面有着极其重要的地位,粘弹性表面活性剂可作为理想的压裂液、酸化液、砾石填充及三次采油措施流体,有着极其出色的性能。详细介绍了粘弹性表面活性剂流变特性及研究现状;简要概述了粘弹性表面活性剂的研究方法极其在酸化、压裂等方面的应用,阐述了其典型优点及在现阶段油田应用中的不足。     

粘弹性表面活性剂溶液及其在油田中的应用潜力

介绍了近几年人们研究的粘弹性表面活性剂溶液的组成, 溶液的内部微观结构和流变特性, 分析了粘弹性表面活性剂在油田中的应用前景, 指出了油田想经济有效地利用粘弹性表面活性剂溶液尚需做的工作。     

粘弹性表面活性剂基压裂液的研究与分析

粘弹性表面活性剂基压裂液（VES压裂液）作为环保压裂液在国内外油田的应用已经取得良好的效果,对储层无污染,且能提高充填层导流能力。论述了粘弹性表面活性剂基压裂液的体系组成、主要特点和压裂机理。该压裂液及剪切稳定性、零伤害性、自动破胶性和低滤失性于一体,在油田具有广阔的应用前景。特别是纳米技术的应用,进一步优化了VES压裂液体系,使该压裂液也适应于干气气藏。介绍了VES压裂液在国内外的研究进展,提出了其应用的优越性和存在的不足。     

酸化压裂液用高效复合型表面活性剂GZP-06的性能研究

根据行业标准对高效复合型表面活性剂GZP-06进行了室内评价。结果表明,在20%盐酸溶液中,GZP-06表面活性剂使用浓度≥0.3%时,表面张力25.69 m N/m,界面张力1.3 m N/m,返排性能提高率达78.8%,腐蚀速率≤0.8 g/(m2·h),且具有很好的配伍性、热稳定性、抗矿化度能力,可以满足油田压裂酸化的施工需求。     

酸化压裂液用高效复合型表面活性剂GZP-06的性能研究

根据行业标准对高效复合型表面活性剂GZP-06进行了室内评价。结果表明,在20%盐酸溶液中,GZP-06表面活性剂使用浓度≥0.3%时,表面张力25.69 m N/m,界面张力1.3 m N/m,返排性能提高率达78.8%,腐蚀速率≤0.8 g/(m2·h),且具有很好的配伍性、热稳定性、抗矿化度能力,可以满足油田压裂酸化的施工需求。     

表面活性剂溶液研究进展

综述了近年来关于表面活性剂分子溶液的研究进展,介绍了表面活性剂分子不仅在水溶液中几种不同聚集方式,而且在有机溶剂中也可发生聚集现象,甚至形成液晶,以及发生这些聚集作用的疏水效应的热力学理论探讨。     

表面活性剂酸液体系在基质酸化及酸压中的应用分析

自从1997年以来,有一公司推出了基于阳离子粘弹性表面活性剂的清洁压裂液,这种弹性表面活性剂技术已经越来越广泛地应用于油气田的增产措施中。按照阳离子粘性表面活性剂以往的使用经验,在最近的两年时间里,国外经过研究,出现了具有比较优越性能的基于表面活性剂的粘弹性酸。本文对这种酸液体系在基质酸及酸压的应用和其他酸液体系相比较所具有的优点和作用的机理进行了分析,对它的粘弹性行为和流变性进行了介绍,还有其流变性受各种酸液添加剂的影响。     

表面活性剂／大分子混合溶液的流变性

本报道了不同表面活性剂／大分子混合体系流变性随表面活性剂浓度的变化规律。离子型表面活性剂使非离子大分子表现出聚电解质的粘度行为，大分子的存在也可使棒状胶束转化为球状胶束，从而使粘度降低。     

表面活性剂对聚合物溶液流变性的影响

本文详细研究了表面活性剂对HPAM溶液流变性的影响。研究结果表明,HPAM溶液的粘度随OP-10加量的增加变化不明显,而其表观粘度都随SDBS的加入而持续降低,并且水解度越小,降低程度越明显。研究结果还表明,溶液粘度变化趋势与表面活性剂临界胶束浓度之间没有明显联系。     

环保型MES粘弹性胶束溶液的流变性

用流变学方法研究了可生物降解阴离子表面活性剂脂肪酸甲酯磺酸钠（MES）在NaCl溶液中从球状胶束转变成蠕虫状胶束的生长过程,分析了两性表面活性剂十二烷基甜菜碱（BS-12）对MES胶束溶液流变行为的影响机制。首先,测量了MES粘弹性胶束体系剪切粘度（η）和剪切速率的关系,得到零剪切粘度（η0）;然后由动态振荡实验,得到复合粘度｜η＊｜、动态模量（储能模量G＇、损耗模量G″和结构松弛时间τs）等物理量;应用Cox-Merz规则和Cole-Cole图,证实了MES（3.0%～5.0%）/NaCl（3.0%～5.0%）/BS-12（0.5%～0.9%）体系形成蠕虫状胶束,且蠕虫状胶束的动态粘弹性在MES（3.5%～5.0%）/NaCl（3.5%～5.0%）/BS-12（0.5%～0.9%）范围是符合Maxwell模型的线性粘弹性流体。     

黏弹性表面活性剂压裂液的研究与应用进展

黏弹性表面活性剂压裂液是以黏弹性表面活性剂为主剂的清洁压裂液。黏弹性表面活性剂压裂液体系具有破胶后无残渣、携砂性好、滤失控制性能好等特点,但随着对环保问题的日益重视及钻井深度的不断增加,丰富黏弹性表面活性剂压裂液体系迫在眉睫。本文介绍了黏弹性表面活性剂压裂液的发展和应用。根据压裂液配方不同,将其分为常规黏弹性表面活性剂压裂液和非常规新型黏弹性表面活性剂压裂液,总结了不同种类的黏弹性表面活性剂压裂液的组成、耐温耐剪切等性能及应用情况。分析表明,降低成本、研制简单的配制工艺是常规黏弹性表面活性剂压裂液的主要发展方向;在油田进行大规模实际应用及得到更完善的体系是非常规新型黏弹性表面活性剂压裂液的主要发展方向。     

新型连续混配型清洁压裂液体系研究

通过对粘弹性表面活性剂分子结构的分析,筛选出了低温下溶解性能好、易成胶的长链烷基季铵盐表面活性剂VES-1、VES-2,并通过与激活剂(水杨酸钠)、聚合醇等进行配方优化组合,确定了YCQJ-2清洁压裂液稠化剂的配方,同时评价了1.0%～5.0%YCQJ-2清洁压裂液的性能。结果显示,YCQJ-2清洁压裂液稠化剂与清水按照一定比例混合,即可形成粘弹性较好的冻胶,破胶容易,表/界面张力低,对岩心的伤害率低于15.0%,而且可以实现就地连续混配、连续施工,简化了施工程序,节约成本,保护环境。     

双子表面活性剂类清洁压裂液的研究进展

压裂技术是提高低渗透油气藏生产能力和油气井采收率的重要手段,而压裂液是影响压裂效果的关键因素。相较于水基植物胶压裂液和以单链表面活性剂为稠化剂的传统清洁压裂液,双子表面活性剂类清洁压裂液在耐温、携砂和保护油气层等使用性能上更具优势,是新一代清洁压裂液发展重点。本文综述了双子表面活性剂类清洁压裂液制备、性能及应用的研究进展,分析比较了阳离子双子表面活性剂类清洁压裂液、阴离子双子表面活性剂类清洁压裂液、两性双子表面活性剂类清洁压裂液等的优缺点,讨论了双子表面活性剂类清洁压裂液在油田领域的应用现状：阳离子双子表面活性剂类清洁压裂液的制备方法成熟,耐温性能较好,可以应用于中高温油田,但是其生产成本较高;阴离子双子表面活性剂类清洁压裂液能有效减少表面活性剂在地层的吸附损失,降低储层渗透率伤害,但是其合成条件苛刻,耐温性不高,适用于中低温油田;两性双子表面活性剂类清洁压裂溶液的耐温性好,但是其制备过程繁琐、成本高,难以大规模推广应用。对双子表面活性剂类清洁压裂液的研究前景进行了展望：发展低成本的合成方法及耐高温双子表面活性剂类清洁压裂液的制备及应用。     

粘弹性清洁压裂液的性能评价与应用

采用一种长链脂肪酸季铵盐类阳离子表面活性剂配制成粘弹性清洁压裂液,室内性能评价结果表明,该压裂液的最佳使用浓度为1.5%².0%;60℃时静态滤失系数为3.15×10-4m/min1/2;静态悬砂速度为0.25 mm/s,常温下与原油混合可迅速破胶;具有良好的耐温性能(65℃)、稳定性和抗剪切性能,与地层水配伍性良好;岩心伤害率9.9%2.0%;60℃时静态滤失系数为3.15×10-4m/min1/2;静态悬砂速度为0.25 mm/s,常温下与原油混合可迅速破胶;具有良好的耐温性能(65℃)、稳定性和抗剪切性能,与地层水配伍性良好;岩心伤害率9.9%¹0.3%,比瓜胶压裂液下降了65%。在同类井况条件下,粘弹性清洁压裂液和瓜胶压裂液现场应用对比实验结果表明,该清洁压裂液在增油效果上具有一定优势,推广应用前景良好。     

Viscoelastic surfactant fluids filtration in porous media: A pore-scale study

We investigated the flow of viscoelastic surfactant (VES) solutions, an important type of fracturing fluids for unconventional hydrocarbon recovery, through a diverging–converging microfluidic channel that mimics realistic unit in porous media. Newtonian fluid and viscoelastic hydrolyzed polyacrylamide (HPAM) solution were used as control groups. We vary Deborah numbers (De) up to 61.2, and found that the flow patterns of HPAM and VES solutions become very different once De ≥ 6.12. This is attributed to different generation mechanisms of viscoelasticity, thus different responses to extensional rates at pore-throats, for HPAM and VES solutions. It results in significantly smaller pressure drop of VES solutions through the microchannel compared to HPAM solution. It interprets higher filtration loss of VES solution than HPAM in core experiments and in field observations. The set-up can be generalized as a prototype to effectively evaluate the filtration of fracturing fluids.     

A review of fracturing fluid systems used for hydraulic fracturing of oil and gas wells

Hydraulic fracturing has been used by the oil and gas industry as a way to boost hydrocarbon production since 1947. Recent advances in fracturing technologies, such as multistage fracturing in horizontal wells, are responsible for the latest hydrocarbon production boom in the US. Linear or crosslinked guars are the most commonly used fluids in traditional fracturing operations. The main functions of these fluids are to open/propagate the fractures and transport proppants into the fractures. Proppants are usually applied to form a thin layer between fracture faces to prop the fractures open at the end of the fracturing process. Chemical breakers are used to break the polymers at the end of the fracturing process so as to provide highly conductive fractures. Concerns over fracture conductivity damage by viscous fluids in ultra‐tight formations found in unconventional reservoirs prompted the industry to develop an alternative fracturing fluid called “slickwater”. It consists mainly of water with a very low concentration of linear polymer. The low concentration polymer serves primarily to reduce the friction loss along the flow lines. Proppant‐carrying capability of this type of fluids is still a subject of debate among industry experts. Constraints on local water availability and the potential for damage to formations have led the industry to develop other types of fracturing fluids such as viscoelastic surfactants and energized fluids. This article reviews both the traditional viscous fluids used in conventional hydraulic fracturing operations as well as the new family of fluids being developed for both traditional and unconventional reservoirs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40735.     

Preparation of degradable amphoteric surfactant and property evaluation of clean fracturing fluid

The main agent of clean fracturing fluid, cationic quaternary ammonium salt surfactant, is difficult to degrade in natural conditions because of its long alkyl chain. In this study, a biodegradable amphoteric surfactant, stearate sulfobetaine (SESB), was synthesized by esterification of long-chain stearic acid and N,N-dimethyl ethanolamine followed by quaternization to serve as the main agent of clean fracturing fluid. The structure of the synthetic degradable surfactant was verified by infrared and ¹H-nuclear magnetic resonance spectroscopies. In addition, a series of indoor performance evaluations were carried out, including shear resistance, viscoelasticity, sand carrying capacity, and gel-breaking performance. A series of experimental evaluations showed that the clean fracturing fluid prepared with 2% SESB and 0.4% EDTA-4Na had an excellent comprehensive performance. The apparent viscosity was higher than 50 mPa s at 80°C for a shear rate of 170 s⁻¹. It has good heat and shear resistance performance. In addition, the system processed high shear stability and recovery at room temperature. According to the viscoelastic test, the system mainly relies on elasticity to carry sand. The static settling velocity of sand was 0.042 mm/s under high-temperature conditions of 95°C.     

Potential applications of poly(vinyl alcohol)‐congo red aqueous solutions and hydrogels as liquids for hydraulic fracturing

The authors report on the viscoelastic characterization of guar hydrogels obtained through complexation reactions with borax ions. These gels are compared with hydrogels obtained from poly(vinyl alcohol) of different degree of hydrolysis through complexation reactions with congo red. The effect of the degree of hydrolysis and both, the concentration of PVA and the concentration of congo red, on the viscoelastic properties of the hydrogels is analyzed. The potential use of the PVA‐based hydrogels as hydraulic fracturing liquids is discussed in relation to the commonly used fracturing liquid based on the guar–borax system. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of a salt-responsive Gemini viscoelastic surfactant for application to solids-free drilling fluids

In order to solve the problem of poor rheological properties of solid-free drilling fluids in salt-bearing formations and prevent drilling accidents such as lost circulation, formation collapse, and wellbore instability, it is crucial to develop a new type of viscosifier. In this study, a salt-responsive Gemini viscoelastic surfactant (NT-1) was synthesized by using erucamide as a hydrophobic chain and introducing a benzene ring and a carboxyl group into the linker. In addition, it is used as a viscosifier for solid-free drilling fluids. The structure of the surfactant was characterized by ¹H nuclear magnetic resonance (NMR), ¹³C NMR, Fourier transform infrared spectroscopy, and electrospray ionization tandem mass spectrometry (ESI-MS), and its physicochemical properties were determined by surface tensiometer, thermogravimetric-differential scanning calorimetry, dynamic lighting scattering and rheometer. Its performance in solid-free drilling fluids was evaluated according to the American Petroleum Institute (API) standard. The results show that the surfactant has a low critical micelle concentration (31.74 μmol/L), excellent thermal stability and water solubility. In particular, NT-1 can self-assemble into worm-like micelles under the action of salt, and the spatial network structure formed by the interweaving of these micelles can endow the drilling fluid with good rheology and viscoelasticity. NT-1 is compatible with conventional drilling fluid polymer additives, which can effectively improve solid-free drilling fluids' rheological properties and fluid loss properties in salt layers. The temperature resistance in drilling fluid systems can reach 120°C. This work verifies the feasibility of using viscoelastic surfactants as viscosifiers in solid-free drilling fluids and provides new ideas for developing salt-responsive smart drilling fluids.