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。     

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.     

溶剂对聚合物减阻剂流变行为和减阻性能的影响

采用博力飞旋转粘度计测定了减阻剂在不同溶剂中溶液的流变性能,通过减阻剂室内模拟环道评价装置测定了不同溶剂合成的聚合物的减阻率.结果表明,减阻剂属于典型的剪切增稠型非牛顿流体;减阻剂在不同溶剂中溶液的粘度随着温度升高而降低;当环己烷与减阻剂的溶度参数相等时,减阻剂在环己烷中的溶解性能最好.并探讨了剪切增稠流体的减阻机理,分析了不同溶剂合成的减阻剂对减阻性能的影响.     

医用导管用热塑性聚氨酯加工特性研究

对用于制造中心静脉导管的硫酸钡(BaSO4)填充热塑性聚氨酯(TPU)的加工性能,尤其是流变性能进行了实验研究。利用毛细管流变仪,通过改变TPU干燥时间、加热时间、挤出温度、挤出速率等参数,研究了含水量,加工温度、热机械历史等因素对TPU剪切黏度,流动稳定性以及表观质量的影响。研究表明:含水量对TPU的黏度影响很大,加工必须保证原料充分的干燥。在熔融加工温度范围内,TPU流变性能对温度变化非常敏感,不仅要精确控制加热温度,还要控制好加热时间。     

A study of shape optimization on the metallic nanoparticles for thin-film solar cells

The shape of metallic nanoparticles used to enhance the performance of thin-film solar cells is described by Gielis'' superformula and optimized by an evolutionary algorithm. As a result, we have found a lens-like nanoparticle capable of improving the short circuit current density to 19.93 mA/cm². Compared with a two-scale nanospherical configuration recently reported to synthesize the merits of large and small spheres into a single structure, the optimized nanoparticle enables the solar cell to achieve a further 7.75% improvement in the current density and is much more fabrication friendly due to its simple shape and tolerance to geometrical distortions.     

Characterization of the surface properties of nanoparticles using moisture adsorption dynamic profiling

Adsorption and retention of molecular contaminants on nanoparticles (NPs) is a major factor in determining the environmental and health effects of the particles. A method has been developed for characterizing the surface properties that contribute to the adsorption and desorption interactions. This method uses a sample cell and an in-situ FTIR to obtain the time profiles of dynamic interactions of adsorbing species on NP samples. The results are then analyzed using a process simulator to determine the fundamental properties such as capacity, affinity, rate expressions, and activation energies of NP interactions with contaminants. The method is illustrated using moisture as a representative model compound and particles of SiO₂, HfO₂, and CeO₂, which are three oxides used in semiconductor manufacturing. The results indicate that the surface interaction parameters are both species and particle size dependent. SiO₂ has the highest adsorption capacity and therefore most prone to the adsorption of moisture and similar contaminants. However, the affinity of the NPs for H₂O retention is highest for CeO₂ and lowest for SiO₂. Factors contributing to the environmental and health impact of NPs (extent of surface coverage, capacity, activation energy of retention) are higher for smaller particles of the same oxide.     

苏氨酸基于表面活性效应在碳糊电极上的伏安行为研究

研究了苏氨酸在表面活性剂存在下于碳糊电极上的电化学行为,发现表面活性剂能显著提高苏氨酸的氧化电流,在此基础上,建立了一种直接测定苏氨酸的电化学方法。优化了测定条件,即介质的pH、扫描速度、富集时间和表面活性剂的种类等。氧化峰电流与苏氨酸在2.0×10-7~3.0×10-5mol/L之间呈良好的线性关系,检出限为7.56×10-9mol/L。应用于实际样品分析,回收率为97%~105%。     

表面活性剂(PVA)浓度对电子束制备纳米铜的影响

在水溶液中,常温常压下使用聚乙烯醇(PVA)为表面活性剂,用电子束辐照方法可以成功制备纳米铜粉。利用紫外可见分光光度计(UV)和激光粒度衍射仪(LSPSDA)考察了表面活性剂浓度对纳米铜粒径分布和团聚的影响。在一定范围内随着PVA浓度的增大纳米铜的粒径减小到13nm。X射线衍射(XRD)和透射电子显微镜(TEM)结果表明PVA浓度为0.88g/100mL,pH值在5~9之间时,能得到纯的纳米铜,其粒径分布为15~40nm。     

Process simulation using the expanded fluid model for viscosity calculations

The expanded fluid (EF) viscosity model was implemented and further developed for efficient integration into a commercial process simulator (VMGSim™). The model has three adjustable parameters per component and its inputs are density, pressure and low pressure gas viscosity. The model was adapted to use densities determined by the Rackett correlation (liquid phase) and the Advanced Peng–Robinson Equation of State (vapor phase). The enhanced EF model fit experimental viscosities of pure hydrocarbons, water and polar compounds important for the simulation of oil and natural gas systems with average absolute errors just above 5%. The implemented EF model was tested against experimental viscosity data that included hydrocarbon and aqueous mixtures with average absolutes errors of 0.7 and 6.2% respectively. Generalized expressions for the estimation interaction parameters of binary mixtures involving paraffins, naphthenes, aromatics, alcohols, glycols and water were obtained. The EF model was also applied to crude oil (bitumen) examples. The three key developments for the efficient implementation of the EF model in a commercial simulator were: (1) the appropriate selection of phase density models; (2) the automatic determination of model fluid specific parameters; and (3) the use of generalized mixing rules for the calculation of binary interaction parameters.     

Performance evaluation of batch and unsteady state fed‐batch reactor operations for the production of a marine microbial surfactant

BACKGROUND: Biosurfactants are microbially derived surface‐active and amphipathic molecules produced by various microorganisms. These versatile biomolecules can find potential applications in food, cosmetics, petroleum recovery and biopharmaceutical industries. However, their commercial use is impeded by low yields and productivities in fermentation processes. Thus, an attempt was made to enhance product yield and process productivity by designing a fed‐batch mode reactor strategy. RESULTS: Biosurfactant (BS) production by a marine bacterium was performed in batch and fed‐batch modes of reactor operation in a 3.7 L fermenter. BS concentration of 4.61 ± 0.07 g L^?1 was achieved in batch mode after 22 h with minimum power input of 33.87 × 10³ W, resulting in maximum mixing efficiency. The volumetric oxygen flow rate (K_La) of the marine culture was about 0.08 s^?1. BS production was growth‐associated, as evident from fitting growth kinetics data into the Luedeking‐Piret model. An unsteady state fed batch (USFB) strategy was employed to enhance BS production. Glucose feeding was done at different flow rates ranging from 3.7 mL min^?1 (USFB‐I) to 10 mL min^?1 (USFB‐II). USFB‐I strategy resulted in a maximum biosurfactant yield of 6.2 g l^?1 with an increment of 35% of batch data. The kinetic parameters of USFB‐I were better than those from batch and USFB‐II. CONCLUSION: Comparative performance evaluation of batch and semi‐continuous reactor operations was accomplished. USFB‐I operation improved biosurfactant production by about 35% over batch mode. USFB‐I strategy was more kinetically favorable than batch and USFB‐II. © 2012 Society of Chemical Industry     

Fractional factorial design for the optimization of supercritical carbon dioxide extraction of La, Ce and Sm ions from a solid matrix using bis(2,4,4-trimethylpentyl)dithiophosphinic acid + tributylphosphate

In this study, La³⁺, Ce³⁺ and Sm³⁺ were removed from a solid matrix using supercritical CO₂ which contained bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex 301) as a chelating agent and tributylphosphate (TBP) as a co-extractant. The fractional factorial design, 2⁵⁻¹, was employed to optimize the SFE of these ions from spiked filter paper matrices. Effect of five experimental factors: amount of Cyanex 301, flow rate, temperature, pressure and amount of TBP and each factor at two levels on the SFE of these ions were studied and optimized. The results showed that these ions could be quantitatively extracted from the solid matrix at amount of Cyanex 301 of 0.14 g, flow rate of 4 ml min⁻¹, 313 K, 250 bar and amount of TBP of 30 μl. Finally, by employing a regression analysis a model was proposed. Results showed that obtained recoveries are similar to those predicted by the model.