Study of deep transportation and plugging performance of deformable gel particles in porous media

Deformable gel particles(DGPs) possess the capability of deep profile control and flooding. However, the deep migration behavior and plugging mechanism along their path remain unclear. Breakage, an inevitable phenomenon during particle migration, significantly impacts the deep plugging effect. Due to the complexity of the process, few studies have been conducted on this subject. In this paper, we conducted DGP flow experiments using a physical model of a multi-point sandpack under various injection rates and particle sizes. Particle size and concentration tests were performed at each measurement point to investigate the transportation behavior of particles in the deep part of the reservoir. The residual resistance coefficient and concentration changes along the porous media were combined to analyze the plugging performance of DGPs. Furthermore, the particle breakage along their path was revealed by analyzing the changes in particle size along the way. A mathematical model of breakage and concentration changes along the path was established. The results showed that the passage after breakage is a significant migration behavior of particles in porous media. The particles were reduced to less than half of their initial size at the front of the porous media. Breakage is an essential reason for the continuous decreases in particle concentration, size, and residual resistance coefficient. However, the particles can remain in porous media after breakage and play a significant role in deep plugging. Higher injection rates or larger particle sizes resulted in faster breakage along the injection direction, higher degrees of breakage, and faster decreases in residual resistance coefficient along the path. These conditions also led to a weaker deep plugging ability. Smaller particles were more evenly retained along the path, but more particles flowed out of the porous media, resulting in a poor deep plugging effect. The particle size is a function of particle size before injection, transport distance, and different injection parameters(injection rate or the diameter ratio of DGP to throat). Likewise, the particle concentration is a function of initial concentration, transport distance, and different injection parameters. These models can be utilized to optimize particle injection parameters, thereby achieving the goal of fine-tuning oil displacement.

PREPARATION OF HIGH THERMAL EXPANSION COEFFICIENT PORCELAINS FUSED TO METALS

Usually the thermal expansion coefficients (TEC) of metals are higher than that of porcelains. In order to match the TECs in the case of coating porcelains on metals, high TEC porcelains are needed. In this research, the high TEC phase leucite (KAlSi2 O6) in the high TEC porcelain was prepared by sol-gel method. The crystal size of leucite made by sol-gel is about 77nm through controlling the process parameters. The process from xerogel to leucite was investigated by means of DSC (differential scanning calorimetry), TG (thermogravimetry), XRD ( X-ray diffraction) and IR (infrared absorption spectrum). Leucite had been detected after the gel was treated at 900℃, this formation temperature is about 250℃ lower than that of melting method. The porcelain made from 50% of the leucite powder and 50% of low fused temperature frit has an average TEC of 19.2×10-6/℃ C from room temperature to 450℃, which is much higher than the common porcelains.

Determination of H^+ diffusion coefficient in the course of H^+ response of a W/WO_3 pH electrode

A WAVO3 pH electrode was prepared by a method of sol-gel. In order to study the H^＋ response dynamic mechanism, the electrochemical impedance spectroscopy （EIS） experiment was conducted. It was found that the H^＋ response course is controlled by the H^＋ diffusion from the solution to the WO3 film, based on the analysis of EIS spectra. The EIS and potential step method were used to determinate the H＋ diffusion coefficient （D） in the course of H^＋ response of this WAVO3 electrode, and the values of D calculated by these two method correspond very well, which all are about 10^-19cm^2/s The imposed different potential steps make little effect on the calculation of H^＋ diffusion coefficient, and it was found that the limiting Cottrell equation of short elapsed time fits well to the current transient caused by a potential step, based on the analysis of the time constant.

BaTiO_3基PTCR陶瓷材料的Sol-Gel制备方法的改进

改进了 Ba Ti O3 基 PTCR纳米粉体的 Sol-Gel法制备工艺 ,用 XRD、DSC、SEM和 BET等技术考察了粉体特性及其对正温度系数热敏电阻 (PTCR)陶瓷材料电性能的影响规律。结果所得粉体平均粒径为 3 0～40 nm,分布窄 ,团聚轻 ,外貌近球形 ,比表面积为 2 6.2 0 m2 / g,在室温下呈立方钙钛矿结构 ;粉体经造粒、成型并在改进的烧结工艺下获得综合电性能有较大幅度提高的 PTCR陶瓷材料。

氧化石墨烯-丙烯酸聚合深度处理水产养殖尾水低浓度氨氮

选择氧化石墨烯和丙烯酸为主要原料,在引发剂和交联剂作用下,通过超声波作用,在50~55℃下,聚合反应得到凝胶产品;傅里叶变换红外光谱分析样品的溴化钾压片,分析结果表明,吸附剂上有仍然键连有羟基、羰基。选择水产养殖水中的氨氮1~5 mg/L为研究参考目标,体积选择20 mL,加入吸附季吸附剂湿重0.5 g, 16 h后,去除率大于等于91%,处理后出水氨氮浓度小于0.5 mg/L,满足地表水一级排放标准。pH对吸附量影响实验,结果表明,pH大于9有利于吸附,此时,氨水的分布系数大于98%,此时溶液中主要存在的是氨水;吸附饱和后的凝胶通过0.1 mol/L的氯化钠可以实现良好的再生。

在硅基材料上用Sol-gel法制备涂层测定氧扩散系数研究

提出一种测定氧扩散系数新方法。用Sol-gel法制备了Y2O3/SiO2均匀致密的薄膜,能成功解决其它方法无法得到的冶炼所得到的熔体,光学椭偏测定氧化层的膜厚。探讨了氧在薄膜中的扩散,在Wagner理论基础上,用数学方法表达在掺杂SiO2薄膜氧扩散系数与氧化层膜厚的关系。

Diffusion of Acetic Acid Across Oil/Water Interface in Emulsification-Internal Gelation Process for Preparation of Alginate Gel Beads

Alginate has been widely used in cell microencapsulation and drug delivery systems in the form of gel beads or microcapsules.Although an alternative novel emulsification-internal gelation technology has been established and both the properties and the potential applications of the beads in drug delivery systems have been studied,the mechanism has not been well understood compared with the traditional droplet method（external gelation technology）.On the basis of our previous knowledge that the novel technology is composed of complicatedly consecutive processes with multistep diffusion and reaction,and the diffusion of acetic acid across oil/water interface being the prerequisite that determines the occurrence and rate for the reactions and the structures and properties of final produced gel beads,a special emphasis was placed on the diffusion process.With the aid of diffusion modeling and simple experimental design,the diffusion rate constant and diffusion coefficient of acetic acid across oil/water interface were determined to be in the orders of magnitude of 10-6 and 10-16,respectively.This knowledge will be of particular importance in understanding and interpreting the formation,structure of the gel beads and the relationship between the structure and properties and guiding the preparation and quality control of the gel beads.

Sol-gel Derived TiO_2-Bioactive glass-Hydroxyapatite Bioactive Coating on Titanium Alloy Substrate

Coating the hydroxyapatite （HA） on the titanium alloy surface can obtain a bioactive implant with high mechanical properties However, the bonding force between the titanium alloy and the HA was low due to their different coefficient of thermal expansion （CET）. Preparing the multi-layer coating with alleviated thermal stress on titanium alloy substrate is few reported. Fabrication of a TiO2-bioactive glass （BG）-HA bioactive coating was proposed to solve this problem. A particular TiO2 surface was prepared on the titanium alloy substrate by micro-arc oxidation treatment. The BG and HA coating were coated onto the TiO2 surface in turn by using a sol-gel method. The microstructure, surface morphology and phase composition of the coatings were analyzed. The bonding force of coatings was investigated by the nick apparatus. In vitro dissolution was performed by soaking the TiO2-BG-HA coated samples into the simulated body fluid for various periods. Micro-structural observations indicated that no delamination and crack occurred at the interface of HA/BG and BG/TiO2. The bonding between the substrate and coating consists of the mechanical interaction and the chemical bonding. The bonding force could reach about 45 N. The TiO2-BG-HA coating displayed the excellent forming ability of bone-like apatite when it was soaked into the simulated body fluid. This work suggests an innovative way to reduce the internal stress among coatings through varying BG composition to adjust its CTE, so as to enhance the bonding force.

Experimental investigation on migration and retention mechanisms of elastic gel particles(EGPs)in pore-throats using multidimensional visualized models

Knowledge of migration and retention mechanisms of elastic gel particles(EGPs)in pore-throats is essential for the effective application of EGPs as a smart sweep improvement and profile control agent for enhanced oil recovery(EOR).The matching coefficient(defined as the ratio of particle size to pore-throat size)is used to investigate its influence on migration,retention and profile control performance of EGPs.A 1-D continuous pore-throat visualization model(PTVM),a 2-D heterogeneous PTVM and a 3-D heterogeneous core model were constructed and used to investigate pore-scale migration,retention and controlling mechanism of migration and retention characteristics on EGPs profile control.The results of the 1-D continuous PTVM indicated that while the matching coefficient was in the optimal range(i.e.,0.20-0.32),the EGPs could not only smoothly migrate to the deeper pore-throats,but also form stable retention in the pores to resist the erosion of injected water,which was conducive to the effective indepth profile control.The results of the 2-D heterogeneous PTVM verified that the sweep efficiency in low-permeability regions could be significantly improved by in-depth migration and stable retention of EGPs in the pore-throats with an optimal matching coefficient(0.29),which was much better than that in cases with a smaller matching coefficient(0.17)or an excessive matching coefficient(0.39).Moreover,the NMR displacement experiments of 3-D heterogeneous cores were carried out to simulate the EGPs profile control in actual reservoir porous media.Saturation images and T2 spectrum curves of crude oil showed that EOR in the low-permeability layer was highest(56.1%)using EGPs profile control with an optimal matching coefficient,attributing to the in-depth migration and stable retention of EGPs.

凝胶注模-发泡法制备煤矸石多孔吸声材料的工艺研究

本文以煤矸石为基体组分,以十二烷基硫酸钠为发泡剂,以氯化铵为促凝剂,以硼砂为烧结助剂结合凝胶注模法及发泡法制备了多孔吸声材料,并研究了水固比、胶凝剂含量和烧结温度等因素对浆料黏度和多孔吸声材料显气孔率、吸声系数以及抗折强度的影响,最终制得显气孔率为49.54%、1600 Hz频段吸声系数为0.953、抗折强度为2.67 MPa的多孔吸声材料。结果表明:水固比对浆料的黏度和多孔吸声材料显气孔率、吸声系数以及抗折强度都有显著影响;胶凝剂含量主要影响材料的显气孔率,进而影响材料的抗折强度;烧结温度主要影响材料的孔径分布,进而影响材料不同频段的吸声系数。水固比0.35、胶凝剂含量35%(质量分数)、烧结温度700℃为最佳制备工艺参数。

Experimental and computational analysis of the structure-activity relationship of ionic gel electrolytes based on bistrifluoromethanesulfonimide salts for supercapacitors

Ionic gel(IG)electrolytes are emerging as promising components for the development of next-generation supercapacitors(SCs),offering benefits in terms of safety,cost-effectiveness,and flexibility.The ionic conductivity,stability,and mechanical properties of the gel electrolyte are relevant factors to be considered and the key to improving the performance of the SC.However,the structure–activity relationship between the internal structure of IGs and their SC properties is not fully understood.In the current study,the intuitive and regular structure–activity relationship between the structure and properties of IGs was revealed via combining computational simulation and experiment.In terms of conductivity,the ionic liquid(IL)([EMIM][TFSI])in the IG has a high self-diffusion coefficient calculated by molecular dynamics simulation(MDS),which is conductive to transfer and then improves the conductivity.The radial distribution function of the MDS shows that the larger the g(r)between the particles in the polymer network,the stronger the interaction.For stability,IGs based on[EMIM][TFSI]and[EOMIM][TFSI]ILs have higher density functional theory calculated binding energy,which is reflected in the excellent thermal stability and excellent capacitor cycle stability.Based on the internal pore size distribution and stress-strain characterization of the gel network([ME3MePy][TFSI]and[BMIM][TFSI]as additives),the highly crosslinked aggregate network significantly reduces the internal mesoporous distribution and plays a leading role in improving the mechanical properties of the network.By using this strategy,it will be possible to design the ideal structure of the IG and achieve excellent performance.

新型除铯环境材料硅钛酸钠孔道结构化合物(Na_4Ti_4Si_3O_(10))合成及结构表征

通过溶胶凝胶-水热合成法制备出一种新型的硅钛酸钠孔道结构化合物Na4Ti4Si3O10。经XRD、SEM、TEM、X-荧光分析等方法对其晶体结构进行了表征。晶体学数据为:P43,a=b=7.8110?、c=11.9735?、α=β=γ=90°。该化合物具有三维空间结构,组成基本单元为Ti-O八面体簇和Si-O四面体,孔道结构为两端都开放的管状毛细孔。微观形貌为规整的四方晶粒,粒子的平均尺寸为20nm;研究了Na4Ti4Si3O10的化学稳定性、热稳定性以及在整个pH范围内的除铯性能。

非离子型凝胶球在水中的溶胀行为

以过硫酸铵和N,N,N’,N’,-四甲基乙二胺氧化-还原体系引发丙烯酰胺聚合,制备球状非离子型水凝胶。利用带刻度的显微镜记录了凝胶球在水中的溶胀扩散过程,采用Tanaka-Fillmore凝胶溶胀动力学模型进行数学处理,得到凝胶网络扩散系数。在此基础上,进一步考察了交联剂、引发剂、单体浓度对凝胶网络扩散系数的影响,结果表明:随着交联剂用量的提高,扩散系数先变小后增大;增加引发剂﹑单体浓度,扩散系数均增大。对凝胶网络扩散系数-温度理论模型进行修正,更加符合实验结果,可用于凝胶网络扩散系数的预测。

石蜡/SiO_2储能相变材料的制备与热性能研究

以工业石蜡为相变芯材,在硅烷偶联剂参与下,通过溶胶-凝胶法制备石蜡/SiO2储能相变材料。并利用透射电子显微镜,热重分析,傅里叶红外光谱仪和方差扫描量热法等测试技术对石蜡/SiO2储能相变材料的结构和性能进行了测试和分析,最后利用瞬态热线法对石蜡/SiO2储能相变材料的导热系数进行了测试。结果表明,石蜡/SiO2储能相变材料的相变芯材石蜡在吸热熔化后不会渗漏;石蜡/SiO2储能相变材料中石蜡的含量约为39%时,相变温度和相变潜热分别为39.15℃和59.33J/g;石蜡/SiO2储能相变材料的导热系数为0.0845 W/(m·K),可作为一种良好的保温隔热建筑材料。

动态光散射法测定凝胶中大分子有效扩散系数

A new data analysis method of dynamic light scattering of gels with macromolecules was proposed,in which the inhomogeneity of polymer gels was taken into account.The reliability of the method was verified by measuring the effective diffusion coefficient of Lysozyme in polyacrylamide gels.The dependence of the effective diffusion coefficient of macromolecules on monomer concentration was also observed.

PTCR纳米晶粉体的一步法制备及表征

采用一步溶胶－凝胶法制得了含钡、锶、钙、钛、锂、锰、硅和钇等八种元素的无定形干凝胶粉，经７００℃，１ｈ煅烧得ＰＴＣＲ纳米晶粉体，经ＸＲＤ分析测得粉体平均晶粒尺寸范围为１７～３０ｎｍ，且平均粒径随稀土掺杂量（摩尔分数为０．０８％～２．００％）增加呈现先减小后增大的趋势。常温下粉体以立方相存在。粉体经造粒、压片。

采用溶胶-凝胶法在刀具表面制备MoS_2软涂层的研究

在成功地采用柠檬酸溶胶-凝胶法在硬质合金试样表面制备出MoS2软涂层的基础上,采用扫描电镜形貌观察和摩擦系数测定等实验方法研究了MoS2加入量对涂层表面微观形貌及其摩擦性能的影响规律。结果表明,采用溶胶-凝胶法在1.6mol/L柠檬酸水溶液中分别添加13、20和27g/L MoS2粉末条件下,应用刷涂法均可以在硬质合金试样表面得到与基体结合牢固、表面质量较高的MoS2软涂层。所获得的MoS2软涂层的表面形貌呈片状。MoS2软涂层的存在明显地降低了硬质合金试样的摩擦系数,由硬质合金试样的0.58～0.86降低到软涂层的0.18～0.23。而具有不同MoS2加入量的软涂层间的摩擦系数相差不大。软涂层试样的摩擦系数明显低于硬质合金试样的原因与涂层中存在有摩擦系数低、承载力大等优良性能的MoS2以及软涂层的存在改变了原摩擦副材料间的性质等因素有关。

分子筛成核与晶体生长动力学研究 Ⅰ.非自成核体系中修正的 Lechert 模型

通过引入凝胶和晶体介质对液相扩散速率的修正因子，在非自成核体系得到修正的Ｌｅｃｈｅｒｔ分子筛晶体生长动力学模型，给出了诱导期和晶体快速生长期的计算公式，表明了晶种量对诱导期影响的特殊性。与Ｌｅｃｈｅｒｔ模型相比，该模型不仅对Ｙ型、ＺＳＭ－５型和Ｌ型实验晶化曲线的前期和后期进行了较好的拟合，且可通过Ｙ型分子筛晶体生长曲线定性推断导向剂中初始晶种的半径、晶种量和颗粒密度随导向剂老化条件的变化规律。

茨13块弱凝胶注水转向实验及现场实施

常规稠油区块注水开发过程中,受油水粘度和重力因素影响,注入水沿高渗层向低部位突进,严重影响注水开发效果。利用岩心流动实验仪,进行了弱凝胶注入岩心一维多点测压模型室内实验,重点研究了弱凝胶强度、弱凝胶注入压力、阻力系数、水驱残余阻力系数与注入时间、注入距离的关系,分析了岩心渗透率对弱凝胶注入施工的影响。确定了弱凝胶在相同的注入压力条件下优先进入高渗层,并在高渗层中形成有效堵塞,从而降低高渗层渗流能力。现场应用弱凝胶进行常规稠油区块深部调驱试验,实现了注水优势流道的转向。

碳酸盐岩用冻胶酸高温流变性及其酸岩反应动力学研究

针对缝洞型碳酸盐岩储层,为了延长具备支撑能力的酸蚀裂缝,从而实现高温深部穿透,增大油气产量,对新型研制的耐高温的冻胶酸进行了流变性和反应动力学的研究。运用高温高压流变仪测定了弹性模量、粘性模量等;酸岩反应旋转岩盘仪测定得到了反应速率、速率常数、反应级数和氢离子传质系数。结果表明,6种体系中DJS-2的弹性模量大于粘性模量;该体系不同稠化剂浓度酸液的反应动力学方程分别是:J=7.43×10^(-6)×C0.514 9,J=8.38×10^(-6)×C0.454 0和J=7.93×10^(-6)×C0.491 0,对应的传质系数分别为1.904×10^(-8),1.857×10^(-8),1.026×10^(-8)cm^2/s,为工业应用提供了设计参数。