高温高矿化度条件下驱油剂中聚合物分子结构形态及其在中低渗油层中的渗流特性

利用动态光散射(DLS)、电镜扫描(SEM)和岩心驱替实验等方法,对高温高矿化度条件下聚合物溶液和"聚合物/表面活性剂"二元复合驱油体系中聚合物分子线团尺寸及其影响因素和在中低渗油藏环境下的渗流特性进行了实验研究,并对其渗流规律进行了机理分析.结果表明,在高温高矿化度条件下,随聚合物浓度增加,聚合物溶液和"聚合物/表面活性剂"二元复合驱油体系中聚合物分子线团尺寸Dh都呈现"先增大后减小"的变化规律.非离子型表面活性剂以胶束聚集体形式吸附在聚合物分子链上,造成二元复合驱油体系中聚合物分子线团尺寸Dh大于聚合物溶液.在溶剂水矿化度较高和岩心渗透率较低条件下,后续注入水的冲刷和稀释作用造成岩心内滞留聚合物浓度降低,聚合物分子线团尺寸Dh增加,最终导致聚合物溶液和"聚合物/表面活性剂"复合体系的残余阻力系数大于阻力系数.     

香豆素分子模板聚合物的合成与性能研究

以香豆素为模板分子, α-甲基丙烯酸(MAA)、丙烯酰胺(MA)、2-乙烯基吡啶(2-VP)和4-乙烯基吡啶(4-VP)为功能单体, 二甲基丙烯酸乙二醇酯(EGDMA)为交联剂, 利用分子模板技术分别在甲苯、甲醇、氯仿和乙腈溶剂中合成了一系列香豆素分子模板聚合物(MTP), 研究了聚合体系组成对模板聚合物吸附特性的影响. 结果表明, 在所合成的模板聚合物中, 以MAA为功能单体, 乙腈为致孔溶剂, 以1∶4∶30的摩尔比加入模板分子、MAA及EGDMA时制备的模板聚合物吸附容量高、印迹效果和选择性好. 此模板聚合物有作为白芷样品中香豆素吸附分离材料的应用前景.     

三唑酮分子印迹预组装体系的分子模拟与吸附性能

以三唑酮为模板分子,以丙烯酰胺(AM)、丙烯酸(AA)、甲基丙烯酸(MAA)和三氟甲基丙烯酸(TFMAA)为功能单体预组装了分子印迹聚合物体系,采用半经验法和从头算法,利用Hyperchem软件模拟了三唑酮与4种功能单体所组成的分子印迹预组装体系的构型、能量、反应配比及复合反应的结合能,选择复合物结合能最高的功能单体用于分子印迹聚合物的合成.采用密度泛函方法计算了模板与单体在不同致孔剂中的溶剂化能.结果表明,三唑酮与三氟甲基丙烯酸所形成复合物的作用力最强,在非极性溶剂中溶剂化能最弱.由预组装体系的差示紫外光谱法研究发现,一分子三唑酮可与两分子三氟甲基丙烯酸在氯仿中形成氢键复合物,与分子模拟的结果一致.在最佳模拟条件下,合成了三唑酮的印迹聚合物,利用吸附等温线Langmuir和Freundlich模型研究了印迹聚合物的吸附行为及识别机理.上述方法对于分子印迹体系的筛选及分子印迹聚合物性能的预测有重要的意义.     

新型液晶聚合物的分子设计及功能

介绍了新型液晶聚合物的分子设计方法；综述了利用分子间氢键，电荷转移相互作用和防子间相互作用设计得到的新型液晶聚合物复合体系的性质和功能，概述了液晶聚合物ＬＢ膜和液晶聚合物弹性体的分子排布特征和功能，这些研究开拓了液晶聚合物研究的新领域，为液晶聚合物分子排布的控制和功能性研究提供了新方法。     

三元复合驱低浓度体系相行为及中间混合层结构分析

低浓度的表面活性剂ASP(碱/表面活性剂/聚合物)驱油体系溶液与模拟原油混合,研究该体系的相行为和界面张力的变化情况,并应用粒度分析仪和冷冻蚀刻透射电子显微镜技术,对中间混合层的粒径分布及其结构进行研究.发现中间混合层的体积随各组分的浓度变化而有一定的规律性,中间混合层与油相和水相之间的界面张力均能达到超低.特别是得到了冷冻蚀刻电子显微镜照片, 并提出中间混合层为胶束、微乳液、乳状液等表面活性剂聚集体的共存体系,其中微乳液结构占主要地位.这对丰富表面活性剂的理论研究及探讨三元复合驱的驱油机理必将起到重要作用.     

电解质对聚合物分子尺寸、结构形态和渗流特性影响研究

利用动态光散射（DLS）、扫描电镜（SEM）、表观黏度和岩心流动实验等方法,研究了电解质对聚合物分子线团尺寸、结构形态和渗流特性的影响。结果表明,随电解质浓度增大,聚合物分子线团尺寸呈现“减小、增大和再减小”变化趋势。在Ca2+、Mg2+和Na+三种离子中,Ca2+和Mg2+离子对聚合物分子双电层压缩作用更强,因而对聚合物溶液黏度和线团尺寸及其分布影响更大。随着溶剂水电解质浓度的增加,聚合物分子结构形态逐渐由多层次立体无规网状向树枝状和支状转化。在聚合物驱后的后续水驱过程中,注入压力大小受滞留聚合物采出量和仍滞留聚合物分子线团膨胀两因素的影响。聚合物相对分子质量愈大,电解质对聚合物分子线团压缩或和膨胀作用愈强,后续水驱过程中压力升高幅度愈大。聚合物驱和后续水驱所用水的电解质浓度差异愈大,后续水驱阶段压力升高幅度愈大。因此在油田聚合物驱油方案设计时,建议适当增加聚合物驱和后续水驱所用水的电解质浓度差异,这对改善聚合物驱增油效果十分有利。     

环糊精包合作用对疏水缔合聚合物流变调节与应用

近年来,利用超分子作用力调节体系流变行为备受人们关注,已在多领域中展现出广泛的应用前景。而环糊精包合作用是一类重要的超分子作用力,向缔合聚合物水溶液中加入环糊精,将拆散缔合结构,引起粘度和粘弹性急剧下降;竞争客体或酶的加入又会诱导分子间发生新的组装行为,使体系流变性得到恢复。本文综述了基于环糊精包合作用的分子组装与流变调节在理论及应用方面的研究现状,重点介绍了环糊精对不同缔合聚合物溶液的流变影响规律和外加物质对体系流变恢复的调节。     

流动注射-化学发光分子印迹技术测定敌百虫

采用分子印迹技术,以甲基丙烯酸为聚合物基体,敌百虫为模板分子,制备在空间结构和结合位点上与敌百虫匹配的分子印迹聚合物,采用扫描电镜进行形貌的表征.研究该聚合物的结合特性,测定分子印迹聚合物对敌百虫的吸附和选择识别能力,将分子印迹聚合物制备成柱,利用KMnO4、HCl化学发光体系,建立了测定敌百虫的高选择性分子印迹化学发...     

ASP复合驱油体系瞬时界面张力的研究

以胜利油田孤岛试验区原油为油相,用正交试验筛选了碱／天然混合羧酸盐／聚合物驱油体系,讨论了各组分对ＡＳＰ复合驱油体系油水瞬时界面张力的影响,并探讨了各组分艇机理及其在油水界面的吸附机理。     

含甲氧基偶氮苯液晶基元超分子的相行为研究

氢键是分子聚集和识别过程中的重要相互作用,利用分子间氢键,可设计并制备各种超分子体系材料,1989年,Kato等报道了吡啶基和羧酸基通过分子间氢键相互作用形成扩展液晶基元,得到了液晶稳定性增强的超分子液晶复合体系及侧链超分子液晶聚合物;同时,Lehn等报道了带脲嘧啶基和2,6-二酰胺吡啶基两种互补官能团的分子通过三重氢键缔合形成的主链超分子液晶。从此,迅速而广泛的开展利用氢键组装的超分子液晶体系的研究,并已组装合成出低分子型、     

三元复合驱碱/表面活性剂/聚合物模拟原油乳状液稳定动力学特性

基于两相分离的乳状液稳定模型,研究了三元复合驱模拟原油乳状液稳定动力学特性;通过液膜强度和油水界面张力探讨了碱/表面活性剂/聚合物对模拟原油乳状液稳定动力学特性的影响机理。结果表明,乳状液稳定模型可以很好的评价乳状液的稳定性,并得到乳状液的稳定动力学特性;碱浓度小于900 mg/L有利于乳状液的稳定,碱浓度大于900 mg/L不利于乳状液的稳定;表面活性剂和聚合物浓度的增加使得形成的模拟原油乳状液更加稳定;模拟原油乳状液的稳定作用主要是通过碱、表面活性剂降低油水界面张力并增加油水界面膜强度,聚合物通过提高界面膜强度实现的,三者存在协同效应。     

Characterization and demulsification of produced liquid from weak base ASP flooding

Weak base alkali-surfactant-polymer (ASP) flooding technology has been applied in Daqing oilfield to enhance oil recovery. The effects of ASP on the characteristics of oil droplets in produced liquid were investigated. Surfactant can decrease interfacial tension (IFT) and zeta potential, making main contribution to the stability of oil droplets. Weak alkali (Na₂CO₃) can decrease IFT and polymer can decrease zeta potential, resulting in stable oil droplets in produced liquid. The produced liquid from weak base ASP flooding is easier to treat than that from strong base ASP flooding. A mixed demulsifier GFD410-8 was prepared and used to enhance oil–water separation in produced liquid. When the demulsifier dose of 50 mg/kg was used to demulsify the simulated produced liquid with the concentrations of alkali 2000 mg/kg, surfactant 600 mg/kg and polymer 600 mg/kg, water volume and water content after 30 min settling were less than 30% and 1000 mg/L, respectively. The demulsifier also greatly decreased water content in oil phase and oil concentration in water phase for actual produced liquid from oil well. The demulsification mechanism was also investigated in terms of IFT and zeta potential.     

Enhanced heavy oil recovery by organic alkali combinational flooding solutions

Although alkaline/surfactant/polymer (ASP) flooding is successfully applied in oil fields, some disadvantages such as scales, corrosion effects, and viscosity reductions of polymer solutions appear. Usage of organic alkalis can avoid or decrease these disadvantages. In this paper, the physicochemical properties, including interfacial tension (IFT), and viscosity, of organic alkali combinational flooding solutions and their effectiveness as enhanced oil recovery agents are investigated. Monoethanolamine (MEA) is the optimal one for decreasing the IFT among the three organic alkalis studied in this paper. Although MEA cannot decrease the IFT as low as NaOH does, it has good compatibility with both surfactant and the polymer hydrolyzed polyacrylamide (HPAM). MEA not only helps a surfactant solution or HPAM/surfactant mixture attain ultralow IFT values, but can also promote better viscosity stability for HPAM or HPAM/surfactant solutions compared to NaOH. Moreover, core flood experiments show that adding MEA can obtain additional tertiary oil recovery of 6%–10% original oil in place (OOIP) on the top of HPAM or HPAM/surfactant flooding, although MEA has a lower enhanced oil recovery than NaOH. The experimental results show that MEA is a good choice to replace NaOH in enhancing heavy oil recovery.     

Investigating the generation of ferrous sulfide nanoparticles in the produced fluid after acidizing oil wells and its influence on emulsifying stability between oil and water

Studies show that after acidizing operation of oil wells using the alkali/surfactant/polymer (ASP) flooding technology, the produced fluid is emulsified. Since the produced emulsion is stable, it affects the oil–water separation performance. In order to analyze the generation of stable emulsion in the produced fluid after acidizing an oil well, innovative separation experiments were carried out on real oil wells. During the experiments, solid particles in the middle layer of the emulsifying system in the produced fluid after acidizing ASP flooding were extracted and characterized. The generation of the stable emulsifying system in the produced fluid was studied through stability experiments and molecular dynamics simulations. The results showed that the synergistic effect of ferrous sulfide nanoparticles and surfactants was the fundamental reason for the strong emulsifying stability of the produced liquid after acidizing of the ternary composite system. The generation of ferrous sulfide solid particles mainly included two steps. First, sulfate reducing bacteria in injected water by ASP flooding reacted with sulfate in formation water to form hydrogen sulfide. Then, the hydrogen sulfide reacted with iron metal in oil wells and casing of wellbore to form ferrous sulfide particles. It was found that surfactants are adsorbed on the surface of ferrous sulfide nanoparticles. Subsequently, the control ability of surfactant on oil and water phases in the liquid film was enhanced. The performed analyses demonstrate that the adsorption of solid particles to the oil phase was enhanced, while the free motion of molecules in the oil phase at the liquid film position was weakened. The strength of the interfacial film between oil and water was further increased by the synergistic effect of ferrous sulfide nanoparticles and surfactant. The present study is expected to provide a guideline for a better understanding of the efficient treatment of produced fluids in ASP flooding.     

Phase behavior and structure analysis of the middle mixed layer for ASP flooding system at low surfactant concentration

The phase behavior and interfacial tension of alkali/surfactant/polymer (ASP) flooding system and simulative crude oil were investigated, and the size distribution and structure analysis of the middle mixed layer (MML) were also studied by size analyzer and freeze-fracture TEM. It was found that there were some rules between the volume of MML and the concentration of each component, and the interfacial tension between MML and the oil phase or water phase could reach an ultra-low value. Especially, the freeze-fracture TEM micrographs of MML were firstly obtained, and the new viewpoint was put forward that there coexist the structures of micelle, microemulsions and emulsions in MML and the structure of microemulsion is dominant. This would make an important effect on the research of surfactant theory and ASP flooding mechanism.     

油田采出液中微量羧酸盐表面活性剂分析方法研究

油田采出液中化学剂浓度的检测是三元复合驱动态评价的重要指标之一。本文针对现场提出的对微量羧酸盐表面活性剂的检测问题,建立了一种用紫外分光光度法测定微量羧酸盐表面活性剂分析的新方法。该法简便、准确快速,线性范围宽,回收率在94.4-103.1%之间,相对标准偏差为1.38%。并根据油田生产的实际情况,探论了碱、聚合物、原油等干扰因素对测定的影响,结果满意。     

Mechanistic Simulation Studies on Viscous-Elastic Polymer Flooding in Petroleum Reservoirs

Based on the theory and application developments of polymer flooding on enhancing oil recovery, an improved mathematical model has been developed to simulate the mechanism of viscous-elastic polymer flooding. IMPES method has been presented to solve the polymer flooding model considering the viscosifying effect of elasticity, the effect of decreasing residual oil and the degradation of polymer molecules. The validation of the model is approved by an experiment. A simulation example was carried out using the developed numerical simulator. The enhanced oil recovery mechanism was discussed for viscous-elastic polymer flooding, and corresponding influencing factors were also studied.     

Characterization of suspended solids in produced water in Daqing oilfield

The concentration and size of suspended solids (SS) in the treated produced water beyond the criteria of injection water in Daqing oilfield have raised great concerns in recent years. The SS in produced water from water, polymer and alkali–surfactant–polymer (ASP) flooding were successfully separated and characterized using some analytical techniques in this study. X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and heating method reveal that some organic compounds besides crude oil were present in the SS samples, and polyacrylamide was found in the SS from polymer and ASP flooding. X-ray diffraction (XRD) shows some crystal inorganic substances such as SiO₂, Fe₂O₃, Fe₃O₄, and BaSO₄ in the SS samples, and XPS analysis indicated that several iron compounds with different valences were present in the three SS samples. The mean diameters of three SS samples were 22.89, 11.28 and 17.61 μm, respectively. Most importantly, the aggregates formed by the SS and oil droplets as well as the small SS adsorbed on the surface of oil droplets were observed using a microscope, indicating that the SS can be removed with crude oil, and crude oil also contributes to the determination of the SS values.     

What is the Criterion for Selecting Alkaline/Surfactaint/Polymer Flooding Formulation: Phase Behavior or Interfacial Tension

An experimental study on determination of alkaline, surfactant, polymer (ASP) flooding systems using natural mixed carboxylate was conducted to examine the decisive factor for ASP flooding, phase behavior or interfacial tension. The volume and color of middle phase liquid were observed, the transient interfacial tension at different salt and alkaline concentrations were measured and, finally, coreflood test in laboratory were made. The results showed the flooding system with larger volume and brown color of middle phase emulsion sometimes not to obtain better oil recovery efficiency. The primary and more important phenomenon affecting the oil recovery is a lower or ultralow minimum interfacial tension value at the crude oil/soluble phase interface.