Preparation and performance evaluation of the slickwater using novel polymeric drag reducing agent with high temperature and shear resistance ability

Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction performance.However,their performance is severely affected at high temperatures.Drag reducing agent is the key to determine the drag reducing performance of slickwater.In this work,in order to further improve the temperature resistance of slickwater,a temperature-resistant polymeric drag reducing agent(PDRA)was synthesized and used as the basis for preparing the temperature-resistant slickwater.The slickwater system was prepared with the compositions of 0.2 wt%PDRA,0.05 wt%drainage aid nonylphenol polyoxyethylene ether phosphate(NPEP)and 0.5 wt%anti-expansion agent polyepichlorohydrindimethylamine(PDM).The drag reduction ability,rheology properties,temperature and shear resistance ability,and core damage property of slickwater were systematically studied and evaluated.In contrast to on-site drag reducing agent(DRA)and HPAM,the temperature-resistant slickwater demonstrates enhanced drag reduction efficacy at 90℃,exhibiting superior temperature and shear resistance ability.Notably,the drag reduction retention rate for the slickwater achieved an impressive 90.52%after a 30-min shearing period.Additionally,the core damage is only 5.53%.We expect that this study can broaden the application of slickwater in high-temperature reservoirs and provide a theoretical basis for field applications.

Effect of Shrinkage Reducing Agent and Steel Fiber on the Fluidity and Cracking Performance of Ultra-High Performance Concrete

Due to the low water-cement ratio of ultra-high-performance concrete(UHPC),fluidity and shrinkage cracking are key aspects determining the performance and durability of this type of concrete.In this study,the effects of different types of cementitious materials,chemical shrinkage-reducing agents(SRA)and steel fiber(SF)were assessed.Compared with M2-UHPC and M3-UHPC,M1-UHPC was found to have better fluidity and shrinkage cracking performance.Moreover,different SRA incorporation methods,dosage and different SF types and aspect ratios were implemented.The incorporation of SRA and SF led to a decrease in the fluidity of UHPC.SRA internal content of 1%(NSRA-1%),SRA external content of 1%(WSRA-1%),STS-0.22 and STE-0.7 decreased the fluidity of UHPC by 3.3%,8.3%,9.2%and 25%,respectively.However,SRA and SF improved the UHPC shrinkage cracking performance.NSRA-1%and STE-0.7 reduced the shrinkage value of UHPC by 40%and 60%,respectively,and increased the crack resistance by 338%and 175%,respectively.In addition,the addition of SF was observed to make the microstructure of UHPC more compact,and the compressive strength and flexural strength of 28 d were increased by 26.9%and 19.9%,respectively.

Capping effect of reducing agents and surfactants in synthesizing silver nanoplates

The effect of reducing agents and surfactants on controlling the silver nanoplates was studied. Two reducing agents, trisodium citrate dehydrate (TSC) and potassium tartrate, were used to reduce the AgNO3 solution. In this redox system, polyvinylpyrrolidone (PVP), sodium dodecyl sulfate (SDS) and arabic gum were served as surfactants. The results showed that reducing agents and surfactants both act as the capping agent adhering to the certain facets of silver seeds to block this surface to grow. The relative intensity of reducing agents also takes an active part in influencing the growth rate and direction of silver seeds. It was also found that halides can accelerate the speed of Ostwald ripening by adding Cl?, Br? and I?into the aqueous and have some effects on the morphology of the nanoplates.

Effect of reducing agents on reducing atmosphere in coal-based direct reduction of beach titanomagnetite

Beach titanomagnetite(TTM)provides a cheap alternative source of Fe and Ti,but this ore is difficult to process to make suitable concentrates for the blast furnace.Recently studies showed that it is feasible to separate Fe and Ti by coal-based direct reduction.In this study,beach TTM was selected as the research object,the effects of reducing agents on reducing atmosphere in coal-based direct reduction of beach TTM were analyzed,and the role of volatiles was also studied.The results showed that when bitumite and coke were used as reducing agents of TTM,the CO produced from volatiles was involved in the reduction reaction,and the generated CO_(2) provided the raw material for the reaction of TTM.The reduction effect of bitumite was better than that of coke.The reason is that bitumite+TTM had a higher gas generation rate and produced a higher CO partial pressure,while coke+TTM had a lower gas generation rate and produced a lower CO partial pressure.When graphite was used as a reducing agent,there was a solid-solid reaction in the early stage in the reaction.With the continuous accumulation of CO_(2),the Boudouad reaction started and accelerated.Graphite+TTM also produced a higher CO partial pressure.

Use of reducing agents for the aerobic growth of Campylobacter jejuni

Objective:To produce a technique for the growth of Campylobacter jejuni in aerobic condition Methods:Different combinations of reducing agents were tested in brucella broth and the growth turbidity was compared with tubes containing normal broth only.Microaerophilic environment was also provided in a petri plate seeded with Campylobacter culture by pouring 3 different concentrations（10%,5%and 2.5%） of five reducing agents along with bacto-agar in the lid which was used to cover and seal the culture plate.Six reducing agents were also added in broth in concentration of 0.25 mg/mL of each with different combinations.Results:In lid agar technique,Campylobacter jejuni growth appeared in all three concentrations of reducing agents, that is 10%,5%and 2.5%after 24 hours of incubation but the best results were observed in 10% concentration.The colonial and morphological characters were not affected when the organisms were grown by this technique.Conclusions:It was found that reducing agents enhance the growth of C.jejuni/coli.In combination of FeSO4,Na2CO3 with H3BO3 worked as ideal mixture for the aerobic growth of Campylobacter.This technique is more economical as compared to commercially available media in the market and can be used for the oral facultative and microaerophilic bacterial growth in laboratory.

Utilization of waste polyethylene terephthalate as a reducing agent in the reduction of iron ore composite pellets

The increasing consumption of plastics inevitably results in increasing amounts of waste plastics. Because of their long degradation periods, these wastes negatively affect the natural environment. Numerous studies have been conducted to recycle and eliminate waste plastics. The potential for recycling waste plastics in the iron and steel industry has been underestimated; the high C and H contents of plastics may make them suitable as alternative reductants in the reduction process of iron ore. This study aims to substitute plastic wastes for coal in reduction melting process and to investigate their performance during reduction at high temperature. We used a common type of waste plastic, polyethylene terephthalate （PET）, because of its high carbon and hydrogen contents. Composite pellets containing PET wastes, coke, and magnetite iron ore were reduced at selected temperatures of 1400 and 1450℃ for reduction time from 2 to 10 min to investigate the reduction melting behavior of these pellets. The results showed that an increased temperature and reduction time increased the reduction ratio of the pellets. The optimum experimental conditions for obtaining metallic iron （iron nuggets） were reduction at 1450℃ for 10 min using composite pellets containing 60% PET and 40% coke.

Chitosan-supported Borohydride Reducing Agent

A new chitosan-supported borohydride reducing reagent (CBER) was prepared by treatment of KBH4 with the resin of chitosan derivative, which was first synthesized from: the reaction of cross-linked chitosan microsphere with glycidyl trimethylammonium chloride. CBER could reduce aromatic carbonyl compound to corresponding alcohol.

Synthesis of Silver Nanoparticles Using Albumin as a Reducing Agent

The preparation of stable, uniformed silver nanoparticles by the reduction of silver ions using albumin is reported in the present paper. It is a simple process for obtaining silver nanoparticles. The samples have been characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), which reveal the nature of the nanoparticles. These studies conclude that the particles are mostly spherical in shape and have an average size of 26 nm. The UV-vis spectra show that an absorption band, occurred because of the Surface Plasmon Resonance, existing at 443 nm;the Thermogravimetric Analysis (TGA) shows that only 2% of the weight is organic matter. The average particle size was measured with a Nanosizer DLS.

Review on the applications and developments of drag reducing polymer in turbulent pipe flow

Drag reduction phenomenon in pipelines has received lots of attention during the past decades due to its potential engineering applications, especially in fluid transporting industries. Various methods to enhance drag reduction have been developed throughout the years and divided into two categories;non-additives method and additives method. Both categories have different types of methods, with different formulations and applications which will generally be discussed in this review. Among all the methods discussed, drag reduction using polymer additive is as one of the most enticing and desirable methods. It has been the subject of research in this field and has been studied extensively for quite some time. It is due to its ability to reduce drag up to 80% when added in minute concentrations. Reducing drag in the pipe will require less pumping power thus offering economic relieves to the industries. So, this paper will be focusing more on the use of polymer additives as drag reducing agent, the general formulations of the additives, major issues involving the use of drag reducing polymers, and the potential applications of it. However, despite the extensive works of drag reduction polymer, there are still no models that accurately explain the mechanism of drag reduction. More studies needed to be done to have a better understanding of the phenomenon. Therefore, future research areas and potential approaches are proposed for future work.

Cooperative Multi-Agent Reinforcement Learning with Constraint-Reduced DCOP

Cooperative multi-agent reinforcement learning（ MARL） is an important topic in the field of artificial intelligence,in which distributed constraint optimization（ DCOP） algorithms have been widely used to coordinate the actions of multiple agents. However,dense communication among agents affects the practicability of DCOP algorithms. In this paper,we propose a novel DCOP algorithm dealing with the previous DCOP algorithms＇ communication problem by reducing constraints.The contributions of this paper are primarily threefold：（1） It is proved that removing constraints can effectively reduce the communication burden of DCOP algorithms.（2） An criterion is provided to identify insignificant constraints whose elimination doesn＇t have a great impact on the performance of the whole system.（3） A constraint-reduced DCOP algorithm is proposed by adopting a variant of spectral clustering algorithm to detect and eliminate the insignificant constraints. Our algorithm reduces the communication burdern of the benchmark DCOP algorithm while keeping its overall performance unaffected. The performance of constraint-reduced DCOP algorithm is evaluated on four configurations of cooperative sensor networks. The effectiveness of communication reduction is also verified by comparisons between the constraint-reduced DCOP and the benchmark DCOP.

铜渣贫化回收铜的研究现状及展望

铜是现代工业不可或缺的原材料,然而我国铜资源对外依存度高,是典型的“卡脖子”资源。铜主要通过火法冶炼铜精矿制得,冶炼过程渣量大、渣含铜量高达0.5%~5%,远高于我国铜矿的可采品位(0.2%)。因此,研究铜渣贫化回收铜的工艺对提升我国资源保障能力具有重要意义。基于铜/铜锍在渣中的赋存状态、铜损的主要形式,重点综述了现阶段铜渣贫化回收铜的工艺技术,包括火法贫化法、浮选法、湿法处理等,并对未来的研究重点进行了展望。目前,电炉贫化处理量大,技术成熟,但其通常使用煤炭等作为还原剂,由于其密度小于铜渣,反应时大多漂浮渣层表面并燃烧,反应不充分,也不利于大气环保。另外,工业上常使用金属铁棒还原炉底结瘤的磁铁矿,但其密度大于铜/铜锍,在渣液中沉降速度快,对渣层的还原不彻底。因此,开发环保、高效的还原剂逐渐成为火法电炉贫化研究的重点。浮选法是处理天然铜矿的常用手段,但铜渣存在硬度高、伴生关系复杂、粒度分布不均、微细粒多等浮选难点,同时铜渣高温浮选导致捕收剂失活的问题也亟待解决。在处理低品位铜渣时,湿法浸出是常用手段,但化学试剂和废液环保问题难以解决;生物浸出具有性质稳定、对环境无污染,且浸出后金属含量较低等优点,但其浸出周期长、效率低。根据目前贫化工艺的难点,对未来贫化工艺开发与优化进行了展望,如增加外场聚集四氧化三铁以改善铜/铜锍沉降环境、开发环保高效的火法贫化还原剂、探究还原剂对不同铜渣渣型的作用机制以及开发耐高温的铜渣浮选新药剂等。

利用制浆黑液研制混凝土减水剂及其在建筑工程上的应用研究

在制浆造纸过程中产生的大量制浆黑液对环境有很大危害,处理制浆黑液时要把环境和水源的保护考虑在内。目前制浆黑液混凝土减水剂的研发及应用于建筑工程,是安全绿色处理制浆黑液的有效途径,不仅使废料重新利用,还节约了减水剂制造成本,达到双赢效果。制浆黑液研制的减水剂对混凝土制品抗压性能和抗渗性能的提升及其在建筑工程上的应用是建筑行业及制浆造纸行业的巨大突破。废料的二次利用不仅节约了制造成本,还降低了混凝土的生产成本,更好地保护了环境,从而实现了可持续发展,为以后的制浆黑液废液处理提供了新的思考方向和借鉴价值。

从铂化合物制备尾液中回收超细铂粉的研究

将不同的铂化合物制备尾液经过氯化铵沉淀,实现与其他杂质元素的分离,将铂转化为氯铂酸铵中间体,经液相化学还原得到超细铂粉。研究了中间体形态、(NH_(4))2PtCl6溶液浓度、分散剂种类及加入量对铂粉粒度、比表面积、形貌的影响。结果表明,铂化合物尾液种类不影响超细铂粉的形貌及颗粒尺寸,以PVP为分散剂,硼氢化钠为还原剂,在优化条件下制备的铂粉平均粒度约150nm,纯度99.99%,直收率97.8%,颗粒形貌均匀、分散程度高、比表面积及颗粒尺寸均符合超细铂粉国家标准,方法可用于从多种铂类化合物制备尾液直接制备超细铂粉。

一种具有超长侧链的疏水缔合型聚合物的合成及减阻性能评价

采用曲拉通和丙烯酰氯醇解合成一种水溶性可聚合单体,仅使用水作为溶剂合成一种具有超长侧链的疏水缔合型聚丙烯酰胺(HAPAM)作为减阻剂,通过分子动力学模拟方法对比了聚丙烯酰胺、部分水解聚丙烯酰胺和合成的具有超长侧链的HAPAM与水的相互作用,并分别以去离子水和盐水配液改变HAPAM含量,测量不同HAPAM含量的滑溜水在不同流速下的摩阻,并计算相应的减阻率。实验结果表明,具有超长侧链的HAPAM与水的相互作用最强;减阻率随流速的增加而增大,HAPAM含量越高,减阻率达到70%所需的流速越高,减阻率最高可达80%以上;盐对滑溜水的减阻率和黏度有显著负面影响,需提高HAPAM含量才能获得理想的减阻率;SEM表征结果显示,HAPAM在清水和盐水中的分布形态均为网状结构。

基于正交试验的外加剂对混凝土力学性能的试验研究

为了探究复掺外加剂对混凝土的韧性和抗裂性能的影响规律,以期解决工程防护和加固过程中的混凝土开裂、剥落等工程实际问题,通过正交试验研究了速凝剂、早强剂、膨胀剂和粉煤灰对混凝土的抗压强度和劈裂抗拉强度的影响规律。试验结果表明:速凝剂能显著改善混凝土的抗压强度和劈裂抗拉强度;复合早强剂能有效提高混凝土的劈裂抗拉强度;粉煤灰和膨胀剂对混凝土28d抗压强度和劈裂抗拉强度没有显著影响。通过方差分析和数据拟合,可得早强剂和速凝剂的建议掺量分别为4%和1.5%,膨胀剂的最优掺量为3%,粉煤灰的最优掺量为25%。

预制构件用水泥基修补砂浆的制备及应用研究

为修补预制构件施工过程中缺角、裂缝等缺陷,以硅酸盐水泥、硫铝酸盐水泥和半水石膏作为胶凝体系,掺加适量减水剂、乳胶粉和其他助剂,制备一种凝结时间短、早期强度高的水泥基修补砂浆,并对其性能进行研究。结果表明,掺加减水剂可以提高修补砂浆的抗压强度和流动度,掺加乳胶粉会延长砂浆的凝结时间,降低抗压强度,同时砂浆流动度则随乳胶粉掺量的增加先增大后减小。减水剂掺量以0.20%为宜,乳胶粉掺量以5.0%为宜,此时修补砂浆的初、终凝时间分别为15.8、22.4 min,7、28 d抗压强度分别为32.2、55.1 MPa,流动度为212 mm。

稠油化学降黏剂研究进展与发展趋势

在双碳背景下,以热采为主的稠油开采技术如何经济、高效、绿色地提高稠油采收率是研究者关注的重点问题。实现稠油油藏的商业开采,其本质是降低稠油黏度,提高流动能力。文章系统分析了稠油的致黏机理以及各类降黏剂的降黏机理,总结了乳化降黏剂、油溶性降黏剂、纳米降黏剂的合成工艺,评价了不同降黏剂的优势与不足。并对降黏剂发展趋势进行讨论与展望。对现有化学降黏剂的梳理有助于新型降黏剂体系的开发,提高稠油油藏开采效率。

耐盐性PAM-AMPS/Fe_(3)O_(4)纳米减阻剂流变性

采用丙烯酰胺/2-丙烯酰胺基-2-甲基丙磺酸(AM/AMPS)共聚物接枝纳米Fe_(3)O_(4)合成了一种PAM-AMPS/Fe_(3)O_(4)纳米减阻剂,并利用动态流变仪研究了PAM-AMPS/Fe_(3)O_(4)减阻剂的剪切稀释性,分析了纳米Fe_(3)O_(4)、盐含量及剪切作用对其流变行为的影响规律。结果表明:PAM-AMPS/Fe_(3)O_(4)纳米减阻剂的粒径为100~500 nm、黏均分子质量为4.99×10^(6)g/mol;在30℃下,剪切速率大于0.3 s^(-1)时PAM-AMPS/Fe_(3)O_(4)减阻剂表现出显著的剪切稀释特征,该减阻剂具有更复杂的微观结构,其超临界质量分数为0.035%,相比空白聚合物表现出更优良的增黏性能和黏弹性;由于AMPS含有耐温耐盐基团,在NaCl和CaCl2质量分数分别为10%和5%的条件下,PAM-AMPS/Fe_(3)O_(4)减阻剂黏度保留率分别为69%和53%,表现出了较强的耐盐性;同时,该减阻剂在剪切速率1000 s^(-1)条件下剪切3600、7200 s后的黏度回复率分别为100%和94%,表现出良好的耐剪切性。

大掺量固废混凝土的制备及性能研究

将粉煤灰、矿粉、不同类型的钢渣粉按不同质量比(mF∶mK∶mG分别为60∶32∶8、60∶28∶12、60∶24∶16、50∶40∶10、50∶35∶15、50∶30∶20)制备了三元复合掺合料,确定了最佳钢渣粉类型和mF∶mK∶mG。在此基础上,通过调整砂率、水胶比、减水剂掺量等方式制备了大掺量固废混凝土(固废总量≥70%),研究了其工作性、力学及耐久性能。结果表明:综合考虑胶砂流动度、三元复合掺合料的活性指数、经济性和环境效益,推荐选用原状钢渣粉,并控制mF∶mK∶mG为60∶32∶8;制备的大掺量固废混凝土的工作性、力学及耐久性能均较好,满足相关设计要求,并推荐采用聚羧酸减水剂,不推荐采用以萘系减水剂与脂肪族减水剂复配而成的复合减水剂。

高效缓凝减水剂与氧化镁膨胀剂对混凝土性能的影响

研究了不同高效缓凝减水剂(柠檬酸、葡萄糖酸钠、柠檬酸镁、柠檬酸锂)分别与氧化镁膨胀剂的共同作用对混凝土工作性、力学性能、干燥收缩、抗裂性能的影响。结果表明:柠檬酸锂对掺氧化镁膨胀剂混凝土拌合物的坍落度有负面影响,但柠檬酸、葡萄糖酸钠、柠檬酸镁能在一定程度上改善混凝土的工作性;各高效缓凝减水剂均可提高混凝土的力学性能;葡萄糖酸钠、柠檬酸镁、柠檬酸锂均可减少混凝土的干燥收缩;柠檬酸、葡萄糖酸钠、柠檬酸镁均对氧化镁膨胀剂在混凝土中的补偿收缩作用有正向影响,其中,柠檬酸镁、葡萄糖酸钠的效果相对更好;柠檬酸对掺氧化镁膨胀剂的混凝土早期开裂性能有负面影响,会促进裂缝的产生。