Development of a Stimuli-Responsive Gemini Zwitterionic Viscoelastic Surfactant for Self-Diverting Acid

A Gemini zwitterionic viscoelastic surfactant named self diverting acid - gemini sulfonated surfactant (SDA-GS), which has double quaternary ammonium groups, double sulfonate groups, and two hydrophobic tails, was synthesized from oleylamidopropyl dimethylamine, 1,3-propanesultone, and 2, 2-bis(bromomethyl)propane-1, 3-diol. The viscosity of an SDA-GS aqueous solution varies with acid and calcium chloride concentrations. With a decrease in the HCl concentration, the viscosity of the acid solution prepared with SDA-GS increases to a maximum value, followed by a decrease, which results from the aggregation of the surfactant into wormlike micelles and the following disaggregation. Calcium ions generated by the reaction of acid and calcium carbonate can enhance the aggregation of the surfactant to increase the peak viscosity of the acid solution. The peak viscosity of the acid solution prepared by 5 wt.% SDA-GS without calcium ions could only reach 73.2 mPa.s when the HCl concentration was 4 wt.%, but that of the acid solution with calcium carbonate powder added could reach over 200 mPa.s when the HCl concentration was consumed to 4 wt.% and the calcium chloride concentration 21.6 wt.%. The viscoelastic measurements proved that calcium ions can drive the growth of the wormlike micelle. The acid and Ca²⁺ response of SDA-GS can be applied in self-diverting acid to improve the acid displacement in the heterogeneous reservoir. Experimental evaluation showed that the acid solution prepared by SDA-GS and the selected corrosion inhibitor showed a good corrosion inhibition performance and a viscosity variation that makes it an efficient self-diverting acid. The spent acid (21.6 wt.%) with 4 wt.% HCl retained high viscosity over 80 mPa.s at a 170 s⁻¹ shearing rate and at 120°C after 90 min. The parallel core flood tests to simulate in situ application of SDA-GS acid showed that the permeability improvement ratios (K₁/K₀) of the cores could reach 182.3 and 278.4 at 60 and 90°C, respectively.     

Evaluation of Rheological and Thermal Properties of a New Fluorocarbon Surfactant–Polymer System for EOR Applications in High-Temperature and High-Salinity Oil Reservoirs

Thermal stability and rheological properties of a novel surfactant–polymer system containing non‐ionic ethoxylated fluorocarbon surfactant was evaluated. A copolymer of acrylamide (AM) and 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) was used. Thermal stability and surfactant structural changes after aging at 100 °C were evaluated using TGA, ¹H NMR, ¹³C NMR, ¹⁹F NMR and FTIR. The surfactant was compatible with AM–AMPS copolymer and synthetic sea water. No precipitation of surfactant was observed in sea water. The surfactant was found to be thermally stable at 100 °C and no structural changes were detected after exposure to this temperature. Rheological properties of the surfactant–polymer (SP) system were measured in a high pressure rheometer. The effects of surfactant concentration, temperature, polymer concentration and salinity on rheological properties were studied for several SP solutions. At low temperature (50 °C), the viscosity initially increased slightly with the addition of the surfactant, then decreased at high surfactant concentration. At a high temperature (90 °C), an increase in the viscosity with the increase in surfactant concentration was not observed. Overall, the influence of the fluorocarbon surfactant on the viscosity of SP system was weak particularly at high temperatures and high shear rate. Salts present in sea water reduced the viscosity of the polymer due to a charge shielding effect. However, the surfactant was found to be thermally stable in the presence of salts.     

Effects of wood-surface roughness,adhesive viscosity and processing pressure on adhesion strength of protein adhesive

The objective of this research was to study the effects of wood-surface roughness, adhesive viscosity and processing pressure on adhesion strength between soybean protein adhesive and wood, and to seek the relative importance of the individual factors in determining adhesion strength. Processing pressure was found to be the most important factor in determining adhesion strength. An optimum pressure, which was about 4.55 MPa in this research, is needed for development of a strong bond. A higher pressure resulted in reduced adhesion strength, possibly due to damage to the wood surface; a lower pressure also resulted in decreased adhesion strength because of the lack of bond formation. Adhesive viscosity had greater effect on adhesion strength than surface roughness. Contact angle, which was found to be mainly determined by adhesive viscosity and surface roughness, was a major factor controlling adhesive penetration. A smaller contact angle, resulting from lower viscosity and rougher surface, produced deeper penetration, while a larger contact angle, resulting from higher viscosity and smoother surface, produced shallower penetration. An optimum penetration is needed to enhance adhesion strength by developing a three-dimensional interactive zone at the interface. Too deep or too much penetration would result in 'dry-out' at the interface; less penetration would limit the formation of the three-dimensional zone at the interface. Both cases resulted in reduced adhesion strength. Contact angles ranging from 35 to 47° provided the optimum penetration needed for good adhesion. The results of this research could be used as reference to determine optimum process parameters in plywood manufacturing when an aqueous based adhesive is used.     

碳酸盐储层用VES转向酸的黏弹性(英文)

Storage modulus and loss modulus is the main performance index of visco-elastic properties. In this paper the storage modulus and loss modulus of a new diverting acid and their influencing factors were systematically investigated. Besides, the constitutive equations of the diverting acid at different temperatures were elicited from shearing experiments, which show that the visco-elastic surfactant (VES) acid system is a non-Newtonian power law fluid at low temperature and a Newtonian fluid at high temperature. The storage modulus and loss modulus at different temperatures, pH, and VES content in the acid are critical for the design of acid stimulation for oil well, especially when the VES acid is used in this field only on trial and the basic data are in urgent needed for the design and construction of the acidification stimulation.     

油田酸化转向剂研究进展

盐酸酸化、酸压是碳酸盐岩油气藏主要增产措施之一，为了保证在非均质地层中酸液能够均匀推进，必须添加酸化转向剂。本文介绍了三种酸化转向剂：泡沫，聚合物以及新型的粘弹性转向剂。     

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。     

磺基甜菜碱Gemini表面活性剂的合成与应用性能

为了改善储层的非均质性差异,有效提高碳酸盐储层的酸化解堵效果,以长链烷基二甲基叔胺、3-氯-2-羟基丙烷磺酸钠和1,4-二溴丁烷为原料,通过两步反应合成了一系列磺基甜菜碱双子表面活性剂（2C _n -SGS,其中n为疏水链中碳原子数,n=12,14,16,18）自转向酸主剂。以2C16-SGS为例,采用FTIR对中间产物（C₁₆-SGS）及2C_16-SGS的结构进行表征。通过表面张力法测定2C _n -SGS的表面活性,结果表明,2C _n -SGS具有良好的表面活性,随着疏水链的增长,2C _n -SGS的CMC和表面张力均减小,且胶束化能力增强。可用于黏弹性表面活性剂自转向酸酸化技术,具有良好的转向分流能力,优选配方为4% 2C₁₆-SGS+20%盐酸+20%Ca²⁺,而且高黏胶束遇煤油等烃类能够自动破胶降黏,易返排对地层无伤害。     

Phase inversion of polyacrylamide based inverse‐emulsions: Effect of the surfactant and monomer on postinversion equilibrium properties

The influence of the interfacial chemistry on the phase inversion of polymerized water‐in‐oil emulsions has been investigated. For copolymerizations of acrylamide with cationic monomers, the effect of substituting of fatty acid esters and ethoxylated fatty acid esters with ABA block type stabilizers, on the kinetics and extent of phase inversion, were examined. It was determined that the solution viscosity was a valid metric to identify the mechanism by which inversion occurs, while conductivity provided a means to quantify inversion efficiency, Therefore, the interfacial chemistry was found to influence not only the plateau value of the viscosity of the polymer solution but also its kinetics. The most suitable inversion was observed with a polymer emulsion stabilized with low block copolymer stabilizer levels in the blend (8 wt %), relative to traditional fatty acid esters and ethoxylated fatty acid esters. This provided an ultimate solution viscosity 30% higher than for a polymer synthesized under identical conditions though with higher levels of the ABA block stabilizer. Overall, the optimal formulation (8% ABA) was found to liberate 88% of the latent viscosity. Given that the options in regards to inverting surfactants can be, legislatively, limited, the present work makes a case for the selection of the interfacial composition not only for its stability during reaction, and the molecular weight of the synthesized polymer, but also for the extent and rapidity of inversion. The formulation‐composition map approach provided an understanding of phase inversion applied to polymer emulsion and was a useful fingerprint to qualitatively describe the catastrophic mechanism of inversion. The surfactant affinity difference applied to a blend of surfactant was found to be a convenient formulation parameter which allowed us to locate the representative point on the map of the polymer emulsion stabilized with different surfactant blend composition. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Adaptability of a hydrophobically associating polyacrylamide/mixed‐surfactant combination flooding system to the Shengli Chengdao oilfield

We investigated the performance of a combination flooding system composed of hydrophobically associating polyacrylamide (HAPAM) and a mixed surfactant [fatty acid disulfonate anionic gemini surfactant (DMES) plus the nonionic surfactant Triton X‐100 (TX‐100)] under the reservoir conditions of the Shengli Chengdao oilfield. With 1800 mg/L HAPAM and 300–3000 mg/L mixed surfactant, the surfactant–polymer (SP) flooding system reached an ultralow oil–water interfacial tension, and the viscosity of the system was greater than 40 mPa s. After the solution was aged for 120 days, its viscosity was still more than 40 mPa s; this indicated a good aging stability. The core flooding experiments with different porous media permeabilities showed that the SP flooding system created a higher resistance factor and residual resistance factor. In addition, the indoor flooding experiments indicated that the SP combination flooding system increased the enhanced oil recovery by more than 30% over that of the original oil in place compared with the water flooding system. Therefore, it was feasible to use an SP flooding system in the Chengdao oilfield. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40390.     

新型砂岩基质缓速酸化体系的性能研究及应用

针对常规酸化工艺中酸液反应快、作用距离短、溶蚀黏土多、溶蚀石英少、基质改造效果差的缺点,研制了以有机膦磺酸和含氟盐为主要成分、适合于砂岩地层深部酸化的新型基质缓速酸化体系——OPSA酸液体系,并配套开发了酸化工艺技术。该技术经河南油田42井次酸化现场应用,工艺成功率100%,酸化有效率92.9%。     

Copolymer MCJS as a retarder of the acid–rock reaction speed for the stimulation of deep carbonate reservoirs

The fast reaction rate between hydrochloric acid and carbonates causes the most acid consumption near the wells, and the acid cannot penetrate the deeper places of the carbonate reservoir; this limits the application of acidizing modifications for the reservoir. In this study, we chose acrylamide, 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS), allyl alcohol polyoxyethylene ether (APEG), and N‐dimethyl‐N‐vinyl nonadecan‐1‐aminium chloride (DMAAC‐18) to synthesize a quadripolymer (MCJS) that could reduce the reaction rate mentioned previously. The molecular structure of MCJS was characterized by Fourier transform infrared and ¹H‐NMR spectroscopy. The molecular weight and molecular weight distribution of MCJS was determined by gel permeation chromatography. Carbonate rock was analyzed by X‐ray diffraction and energy‐dispersive X‐ray spectroscopy. The retarding properties of the acid mixed with MCJS (MCJS acid) were investigated, and the resulting reaction rate between the acid and carbonate decreased obviously, even at a low viscosity. Scanning electron microscopy and core flood experiments showed that the MCJS could be adsorbed on the carbonate rock surface and form a hydrated film that delayed the reaction. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41471.     

Effect of Branched Alcohols on Phase Behavior and Physicochemical Properties of Winsor IV Microemulsions

The microemulsion phase behavior and physicochemical properties of surfactant–water–alcohol–oil systems are the pioneer laboratory study as a function of alcohol, water content and temperature to develop an experimental investigation for a better understanding of the microstructure of a single phase microemulsion and its stability under reservoir condition during hydraulic fracturing to recover the residual trapped oil. Viscosified surfactants are used as an efficient proppant conducting medium in hydraulic fracturing applications. The physicochemical properties of microemulsions are very helpful for characterization of microemulsions to justify their abilities and screening of surfactants. In the study, two branched alcohols, 2-methyl butan-2-ol, 3-methyl butan-1-ol selected as the cosurfactant in the proposed microemulsion system and their effect in tailoring the viscosity of microemulsions were studied. Microemulsion regions elucidated from Winsor’s pseudophase model of an oleate surfactant show a signatory distribution pattern of components between different domains with non-polar and asymmetric geometry of cosurfactant directs macromolecular alignments; their alignment contributes to a viscous microemulsions (gel) regime. The effect of surfactant and alkali, and the experimental temperature on the rheological properties of the lamellar mesophase were investigated. Phase transit regions and exact microemulsion and viscous microemulsion magnitudes were elucidated with the help of conductivity and viscosity studies of the ternary system as a function of the aqueous fraction and were in good agreement with Winsor’s pseudophase model. Dynamic and steady shear rheological studies showed that the gel is viscoelastic in nature, sustain viscosity and elastic modulus values appropriate for proppant suspension under high shear conditions. The proppant suspension and thermal behavior of ideal gel composition was found to be suitable for Coal Bed Methane and soft rock, clay reservoir stimulation.     

适合安塞油田杏河区块的暂堵剂优选

针对安塞油田杏河区块非均质储层进行低渗透油田暂堵酸化增产工艺研究,通过室内试验研究,进行酸化暂堵剂性能评价,筛选出适合安塞油田的酸化暂堵剂和酸液体系,完善暂堵酸化工艺体系,进行规模化应用,这对高效开发安塞油田具有重要的理论意义和实践意义。     

Composition limits in granulation with active component in the binder

The process of reactive granulation is considered. Sodium carbonate primary particles react with dodecyl‐benzenesulfonic acid droplets to form granules where the active component is an anionic surfactant formed by the reaction. The effect of primary particle size on the maximum binder/solids ratio was systematically investigated and found to be directly proportional to the specific surface area of the primary particles regardless of how this surface area was achieved—whether by monodisperse powders or bimodal powder mixtures. The effect of binder viscosity on the maximum binder capacity has shown a nontrivial behavior: while the maximum binder content increased with increasing binder viscosity for fine primary particles, the opposite trend was observed in the case of coarse primary particles. This behavior was explained by detailed studies of primary particle wetting and binder penetration into particle beds, as well as by microtomography analysis of the internal granule structure. © 2014 American Institute of Chemical Engineers AIChE J, 61: 395–406, 2015     

磺化蓖麻油酸的合成

以浓硫酸磺化蓖麻油酸,得到磺化蓖麻油酸,具有良好的乳化力和渗透力,可作为阴离子表面活性剂,用正交实验优化了磺化反应的工艺条件。结果表明,最佳工艺条件为:n(蓖麻油酸)∶n(浓硫酸)=1∶2,反应温度50℃,反应时间6h。由方差分析和极差分析可知,物料配比n(蓖麻油酸)∶n(浓硫酸)对反应的影响极其显著,其次是反应时间,温度对反应的影响最小。在最优条件下,磺化率可达30%以上,25℃下,粘度>380mPa.s,固含量>80%,产品性能稳定。通过傅立叶红外光谱法、1H NMR、元素分析法、化学分析等鉴定,对合格产品分析可知,得到的磺化蓖麻油酸为高度磺化产品。     

Adsorption of surfactant during chemical enhanced oil recovery

Surfactant is extensively used as chemicals during chemical enhanced oil recovery (CEOR) process. Effectiveness of surfactant CEOR process depends on several parameters like formation of micro emulsion, ultra-low interfacial tension (IFT) and adsorption of surfactant. First two parameters enhance the effectiveness while the last parameter reduces the effectiveness. Micro emulsions are highly desirable for CEOR due to its low interfacial tension (IFT) value and higher viscosity. In this research the size of the emulsions were studied with particle size analyzer to study the liquid–liquid absorption process and the entrapment of oil drops inside surfactant drop. Initially, the average surfactant drop size was found to be 100 nm, after mixing the surfactant slug with reservoir crude, the size was increase up to 10 times. It signifies the formation of micro emulsion between surfactant and oil. Another attempt was done in this research to study the adsorption mechanism of surfactant on reservoir rock. The process of adsorption was studied by Langmuir and Freundlich isotherm to understand the adsorption phenomena. In this study, it was found that the adsorption follows Freundlich isotherm and the adsorption phenomena was chemical for surfactant flooding process. In chemical adsorption phenomena, the rate of adsorption is high because, surfactant molecules are adsorbed layer after layer by the rock surface. Use of alkali along with surfactant reduces adsorption of surfactant since, alkali blocked the active clay sites before interacting with surfactant and hence the adsorption isotherm was found to be Langmuir and phenomena was physical adsorption.     

胶凝剂体系聚合机理及其应用研究

碳酸盐岩裂缝性油藏在复合酸压施工过程中,降低酸岩反应速度、增加酸蚀裂缝的穿透深度是必须要考虑的问题。本文针对使用胶凝剂体系降低酸岩反应速率的方法进行了研究,深入分析了利用胶凝剂体系来降低酸岩的反应速度的机理,包括乳液聚合理论和反相乳液聚合理论。本文详细阐述了乳液聚合的成核机理、乳液聚合的聚结机理、核壳乳胶粒结构、反相乳液聚合的机理和反相乳液聚合与乳液聚合的对应关系。以此理论为指导,结合胜利油田碳酸盐岩裂缝性潜山油藏高温特点,通过室内试验,合成了一种三元共聚水溶性高分子,即YLG-1胶凝剂。酸化压裂室内实验表明YLG-1胶凝剂的综合性能良好,可以应用于胜利油田碳酸盐岩裂缝性油藏的复合酸压作业中。     

The role of liquid penetration in detergency of long-chain fatty acid

The detergency phenomena of a solid oily contaminant assessed with a quartz crystal microbalance (QCM) technique was discussed on the basis of surface energetics. Polyethylene, nylon 6, and cellulose acetate films were prepared on gold electrodes of the QCM by a spin-coating method. Arachidic acid was deposited onto the QCM with and without polymer films by the Langmuir-Blodgett (LB) technique. The QCM was then ultrasonically cleaned in aqueous solutions containing surfactant, ethanol, and alkali. The removal efficiency of the LB films of arachidic acid from the gold and polymer substrates was determined from the frequency change of the QCM due to cleaning. The efficiency was greatest for cellulose acetate, followed by nylon 6, gold, and polyethylene. For every substrate, the removal efficiency was found to increase with increasing surfactant or ethanol concentration. In the presence of sodium hydroxide, the removal efficiency further increased. The experimentally determined contact angles and surface free energies were influenced by surfactant and ethanol concentrations; however, they were not influenced by the addition of sodium hydroxide. This suggested the saponification of arachidic acid under alkali conditions was a major mechanism of fatty acid removal. The dependences of the kind of substrate and surfactant and ethanol concentrations on the removal efficiency were explained in terms of the free energy change resulting from penetration of the detergent solution between the arachidic acid film and the substrate in the zone of contact. Liquid penetration as well as saponification was found to be an oil removal mechanism in the present system.     

碳酸盐岩油藏近井筒区域温度场的模拟

在碳酸盐岩油藏酸化中,近井筒附近的温度场对酸化效果影响很大。通过一种双重尺度模型对这一问题进行了研究,模型考虑了孔隙中的对流传质、传热和液固表面的酸岩反应。结果表明:与实验室常温条件相比,地层高温条件下的酸岩反应速率增快,形成主蚓孔的注酸速度增大(Damköhler数减小),且当注酸速度较大时,突破体积明显下降;当模拟区与外界不发生热交换时(绝热边界),由反应放出的热量使得模拟区的温度上升,造成突破体积比等温边界时的小;若酸液在井筒中不与地层发生热交换,则注酸速度较低时不同地层温度的突破体积几乎没有差别;反之,注酸速度较低时突破体积随着地层温度的上升而增加。     

热化学反应体系研究及其在油田解堵中的应用

探索并确定了一种可大量产热的热化学反应体系,设计了装置与流程对反应产生的气体量与热量进行测算.以该热化学反应体系为基础,配以适当类型和加量的酸、表面活性剂、抑制剂、缓蚀剂、阻垢剂等组分,作为油井解堵剂,在实际应用中大幅度地增加了油层产油量,降低了水层注水压力.