| 题名 | 油田二元驱采出水的乳化稳定性形成与破乳脱稳研究 |
| 作者 | 陈宏 |
| 学位类别 | 博士后 |
| 答辩日期 | 2014-06 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 杨敏 |
| 关键词 | 油田采出水 聚合物/表面活性剂驱 乳化稳定性 破乳剂 界面扩张流变学 冷冻蚀刻复型 oil produced water polyer/surfactant flooding emulsion stability demulsifier interfacial dialational rehology freeze etching replica |
| 其他题名 | Emulsion stability and destabilization of binary produced water from polymer/surfactant flooding process |
| 学位专业 | 环境工程 |
| 中文摘要 | 油田化学驱采出水具有含油量高、驱油剂含量高、悬浮物含量高、矿化度高、粘度大、水质变化大、油滴初始粒径小、乳化稳定性强、油水分离困难的特点，表现出特殊的水质和体系特性，当前尚未建立针对化学驱采出水的分析表征方法体系。二元驱采出水是一种典型化学驱采出水，含有大量聚合物和表面活性剂，目前还不明确其乳化稳定性形成和破乳脱稳的过程机制，缺乏能够有效处理二元驱采出水的工艺和方法。新疆油田已经开展了聚合物/表面活性剂二元驱先导试验，产生了大量的二元驱采出水，亟待解决达标回注处理技术难题。 本研究通过探索利用界面扩张流变学手段研究油水界面特性和分子行为、使用原子力显微镜(AFM)、冷冻蚀刻复型-透射电镜(FER-TEM)和冷冻电镜(Cryo-SEM)等手段来表征乳化体系的微观形貌、采用液相色谱法测定聚丙烯酰胺和石油磺酸盐浓度和采用场流-光散射法测定聚丙烯酰胺分子量，尝试建立油田化学驱采出水的水质和体系特性的表征方法体系。通过配制模拟典型二元驱采出水，分别研究固体颗粒、聚合物和表面活性剂种类及其浓度对油水分离性能的影响，研究二元驱采出水的乳化稳定机理。通过分析油滴粒径、Zeta电位和粘度等指标比较不同有机破乳剂和无机电解质对模拟二元驱采出水的破乳脱稳效果，探索不同化学药剂的破乳脱稳机制。通过表征破乳剂特性和考察单剂处理效果，从工业市售破乳剂中筛选优选破乳剂，探索利用界面扩张流变学手段指导破乳净水剂筛选，开发新疆克拉玛依油田二元驱采出水的处理工艺。主要研究结果如下： （1）界面扩张流变学研究手段可以用于研究驱油剂及表面活性物质分子在油水界面上的吸附过程及其相互作用规律，有望为表征油田化学驱采出水的体系特性提供一种新的手段。FER-TEM方法能够较好表征化学驱采出水中油/水/固的微观形貌结构，能够直观表现溶液中高分子聚合物形成的空间网状结构和其它分散物质如原油的形貌，还能反映出相对位置关系。液相色谱法可被用于测定化学驱采出水中的部分水解聚丙烯酰胺（HPAM）和石油磺酸盐浓度，而测定结果显示它们均随采出时间和位置发生强烈变化，证实了化学驱采出水的复杂易变性。利用场流-光散射法可以测定溶液中的HPAM分子量。 （2）模拟二元驱采出水的乳化稳定性受表面活性剂的影响最大，而固体颗粒和聚合物的影响相对较小。蒙脱土颗粒能够降低油滴的Zeta电位，但浓度高于200 mg/L时与聚合物裹挟大颗粒油滴形成絮状沉淀，破坏了采出水的乳化稳定性。增大10 MDa HPAM的浓度使得采出水的体相粘度升高，在大于500 mg/L时导致了明显的絮凝沉降作用，降低了采出水的乳化稳定性。表面活性剂能够直接改变油滴Zeta电位，通过界面顶替和电性作用直接影响了油滴间的碰撞和聚并过程，主导了采出水的乳化稳定性；增强采出水乳化稳定性的表面活性剂种类排序为：十二烷基苯磺酸钠>Tween-80>Span-80>苯扎氯铵。 （3）模拟二元驱采出水的破乳脱稳过程受合成有机破乳剂的起始剂种类的影响较大，而起始剂含量的影响较小，亲水基亲油基之比（EO/PO比）的影响则最小。聚合氯化铝（PAC）和Al2(SO4)3的破乳脱稳效果最好，投加量500 mg/L时均能将剩余含油量降低到10 mg/L以下；而FeSO4和ZnSO4次之，NH4Cl较差。破乳剂通过电性中和及与HPAM形成的协同絮凝作用，促进了油滴的碰撞聚并，达到了较好的破乳脱稳效果。 （4）针对新疆克拉玛依油田二元驱采出水成功筛选出了处理效果良好的优选破乳剂8#和9#。在投加200 mg/L 8#破乳剂或者100 mg/L 9#破乳剂静置4 h后，含油量及浊度去除率均大于98%，脱出水色较清，基本达到回注水的水质要求。分析不同溶液体系的油水动态界面张力和不同频率下的界面扩张模量的变化规律，一定程度上理解了化学药剂加入前后二元驱采出水体系中表面活性分子的变化及其界面吸附交换重排等行为，有望将界面扩张流变学手段应用于指导筛选破乳净水剂。通过优化破乳剂和絮凝剂的投加种类和投加方式，结合优选破乳剂和“破乳净水（单剂或复配）——重力沉降——PAC混凝——二次沉淀——砂滤出水”的传统物化处理工艺，成功满足了实际二元驱采出水的达标回注处理要求。 |
| 英文摘要 | Oil produced water from chemical flooding processes is characterized by high oil content, high chemicals content, high suspended solids content, high salinity, high viscosity and easy-changing water quality, smaller oil droplets, strong emulsion stability and difficulty to separate. Due to its special water quality and solution properties, analytical methods for characterizing the chemical flooding produced water have not been established yet. The binary produced water from the polymer/surfactant flooding process is a typical chemical flooding produced water, which has high concentrations of polymer and surfactant. Until now the profound emulsion stability and mechanisms of demulsification and destabilization of the binary produced water have not been clearly understood, which leads to the lack of effective treatment processes and methods. The polymer/surfactant flooding process had been applied in Xinjiang Oilfield and then a large amount of binary produced water has been generated. Therefore, treatment technology development for the binary produced water becomes an urgent problem. In this study the interfacial dilational reology was explored to study the oil-water interfacial rheological properties and molecular behaviors occurred in the produced water. Atomic force microscopy (AFM), freeze etching replica - transmission electron microscope (FER-TEM) and Cryo - scanning electronic microscopy (Cryo-SEM) were inspected to characterize the microstructure of the emulsion system. Liquid chromatography (LC) for determining hydrolyzed polyacrylamide (HPAM) and petroleum sulfonate concentrations and field-flow fractionation - light scattering (FFF-LS) for determining the molecular weight of HPAM were examined for chemical-flooding produced water. And then the characterization methodology for chemical-flooding produced water was proposed to set up. Simulated polymer/surfactant produced water was prepared and used to investigate the effect of each component including solid particle, polymer and surfactant on its emulsion stability. Through monitoring indexes of oil droplets, Zeta potential and viscosity, effects of different types of organic demulsifiers and inorganic electrolytes on the demulsification and destabilization of the simulated produced water were investigated. Some demulsifiers from industrial markets were screening by property characterization and treatment efficiency evaluation. Some selected demulsifiers were furtherly investigated the process mechanism by interfacial dilational rehology. Finally, a treatment process for the polymer/surfactant produced water from Karamay Oilfield was proposed. Some main results as follows. (1) Interfacial dilational rheology can be used to discover the adsorption process and its interactions of polymer and surfactant molecules in oil-water interface, and could be provided a new method for characterizing the emulsion property of chemical-flooding produced water. The oil/water/solid microscopic morphology and structure in chemical-flooding produced water could be effectively characterized by FER-TEM. The crossliked network structure formed by the polymer and the morphology of dispered substances such as crude oil and their relative positional relationships could be also obtained. LC can be used to determine HPAM concentration and surfactant concentration in chemical flooding produced water, and both of them could be greatly variaed with produced time and produced position, which demostrated the complexity and variability of chemical flooding produced water. FFF-LS method can be used to determine HPAM molecular weight in solutions. (2) Surfactant had a significant impact on the emulsion stability of the binary produced water but some minor influences for the solid particle and the polymer. Montmorillonite particle could reduced droplet Zeta potential and could destroy the emulsion stability of the produced water at its high concentration over 200 mg/L by forming flocculent precipitations with the polymer. 10 MDa HPAM could directly affect the bulk viscosity and also could destroy the emulsion stability at its concentration over 500 mg/L by enhancing the flocculation in the simulated produced water. Surfactant could significantly increase the emulsion stability due to its strong interfacial property for changing the Zeta potential of oil droplets and enhancing the process of their collision and coalescence. The order of surfactant types for enhancing the emulsion stability of the simulated polymer/surfactant produced water is: SDBS > Tween-80 > Span-80 > benzalkonium chloride. (3) The initiator type of organic demulsifiers had a greatly influence on the demulsification and destabilization process of the binary produced water, corresponding to a minor influence for the initiator content and a slightly influence for the ethylene oxide/propylene oxide (EO/PO) ratio of organic demusifiers. Polyaluminium chlorid (PAC) and Al2(SO4)3 could lead to the best oil-water separation efficiency as the residual oil content was less than 10 mg/L at dosage of 500 mg/L. The demulsification efficiency by FeSO4 or ZnSO4 was also good, but was worse by NH4Cl. By interfacial charge neutralization for facilitating collision and coalescence of oil droplets and the synergistic effect of flocculation with HPAM in the O/W emulsion, demulsifiers could efficiently promote the demulsification and destabilization process. (4) For practical polymer/surfactant produced water from Xinjiang Karamay Oilfield, two demulsifiers 8# and 9# from industrial markert were successfully screened. By adding 200 mg/L demulsifier 8# or 100 mg/L demulsifier 9# into binary produced water and keeping settlement state of 4 h, removal efficiencies of oil content and turbidity were both over 98% and water color of the supernatant was clear, which could satisfy the water quality requirements of oilfield injecting water. Through analyzing the changes of dynamic interfacial tension and the dilational modulus of the oil-water interface with time or oscillation frequency, the surfactant molecular changes and their interfacial behavior as adsorption, exchange and rearrangement could be understood to some extent, and the interfacial dilational rehology could be applied for developing the screening guidance of industrial demulsifiers. After optimized the types and dosing program of demulsifiers and flocculants, a combination process of demulsifier screening and “(single or complex reagent) demulsification - gravity sedimentation - coagulation (PAC) - secondary sedimentation - sand filtration" was proposed for polymer/surfactant produced water treatment, which could successfully meet the water quality standard of oilfield injecting water in Keramay reservoir. |
| 公开日期 | 2015-06-12 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/13453]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 陈宏. 油田二元驱采出水的乳化稳定性形成与破乳脱稳研究[D]. 北京. 中国科学院研究生院. 2014. |
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