【作者】 周朝昕；

【导师】 陈艳玲；

【作者基本信息】 中国地质大学 ， 油气田开发工程， 2013， 博士

【摘要】 目前,油田普遍采用的是混凝沉降+过滤的油田采出水处理技术。但随着聚合物驱在油田的推广应用,聚合物驱含聚采出水水质复杂且难以处理的问题变得越来越突出,油田现有常规水驱采出水混凝沉降+过滤技术及系统已无法满足油田正常生产的要求。因此,针对聚驱含聚采出水组成及成分的变化,开发有效、稳定、廉价的产出水处理及回用技术,不仅有望解决油田继续扩大聚驱作业中的技术难题,而且具有着显著的实际应用价值和良好的环境效益。粉煤灰混凝剂与电絮凝联用将脉冲电絮凝的电中和、电压缩优势与粉煤灰混凝剂的多核无机高聚物的吸附、卷扫优势结合起来,提高含聚污水处理效率,成为集脉冲电絮凝胶体脱稳—旋流混凝反应双向沉降分离为一体的高效处理方法。本论文从粉煤灰混凝剂制备、电絮凝处理研究、化学絮凝机理及电絮凝机理等几个方面开展研究,主要研究内容包括以下几个方面：1.粉煤灰固相反应制备絮凝剂研究1)研究了粉煤灰固相反应制备絮凝剂的反应条件。通过研究原料成分配比、焙烧温度、焙烧时间、固液比、酸浸时间研究对制备产物絮凝性能及稳定性的影响,确定了粉煤灰制备聚硅酸铝铁锌絮凝剂的反应条件：ZnO/粉煤灰质量比为0.3:1、NaOH/粉煤灰质量比为0.6：1,600℃焙烧2h,固液比为0.155g/mL,酸浸时间2h,制备出聚硅酸铝铁锌(PAFZS)。2)利用XRD及红外光谱研究了粉煤灰固相反应生成无机高分在絮凝剂的机理。改变焙烧温度,比较不同焙烧温度条件下固相反应产物与粉煤灰原料的XRD谱图,发现粉煤灰、ZnO与NaOH在高温下发生了固态化合反应,生成了硅酸铁、硅酸铝。焙烧温度从200℃升到650℃,温度越高反应越充分,越有利于酸浸后聚合成为PAFZS.红外谱图表明,在1053cm-1附近存在一个较窄的吸收峰,表明PAFZS中铝、铁、锌连接的羟基(Al-OH-Al、Fe-OH-Fe和Zn-OH-Zn)伸缩振动形成的,并且随着ZnO的加入量的增加,透光率变得更低,说明ZnO的加入有利于Zn-OH-Zn的生成,而阻止聚硅酸胶凝,增加了PAFZS稳定性。在444cm-1附近的吸收峰表明,此处的铝、铁、锌离子与羟基结合共聚的作用加强,将聚铝、聚铁和聚硅基团用羟基键连接反应,从而形成无机高分子PAFZS。3)通过对浊度、聚合物含量去除率研究了PAFZS处理含聚采出水的絮凝性能,聚硅酸铝铁锌絮凝剂(PAFZS)适宜的处理pH范围为5-7。PAFZS处理较低浓度(73.14mg/L)和较高浓度(560mg/L)聚合物废水的处理效果都相对较好；处理较低聚合物浓度(73.14mg/L)的含聚采出水,PAFZS的加药量达到1000mg/L时,聚合物废水的剩余浊度降到1NTU以下,聚合物浓度降到5mg/L以下；处理较高聚合物浓度(560mg/L)的含聚采出水时,PAFZS的加药量达到1400mg/L时,聚合物废水的剩余浊度降到20NTU以下,聚合物浓度降到450mg/L以下；4)通过表面张力、ζ电位的变化研究了PAFZS絮凝机理,发现PAFZS与水中残留聚合物通过电吸附改变含聚采出水ζ电位、表面张力。并且随着PAFZS加量增加,ζ电位绝对值下降。而表面张力先下降,后又上升。在达到表面张力最低点之前,PAFZS处理含聚采出水机理是电中和与吸附卷扫联合作用;在达到表面张力最低点之后,PAFZS处理含聚采出水机理主要是吸附卷扫作用。2.电絮凝处理含聚采出水研究1)研究了多种电极材料电絮凝处理含聚采出水对聚合物、浊度的去除效果,分别筛选出两级电絮凝电极材料,第一级极板材料为不锈钢-不锈钢,中间填充铁屑,第二级铝为消耗性阳极极板材料。以油、浊度、聚合物的去除效果优化电絮凝参数,确定电絮凝时间20min,极板间距2cm,电絮凝电压6V,水样初始pH为6,脉冲频率0.3KHz,占空比0.4。最价操作条件下,电絮凝模拟含聚采出水聚合物去除率达99.9%,浊度降为0.62。2)电絮凝与化学絮凝联合处理含聚采出水研究。研究了多种因素对电絮凝与化学絮凝联合处理含聚采出水去除油、浊度、聚合物的影响,在最佳条件下,二者联用处理模拟含聚采出水可以达到：油1mg/l,悬浮固体5mg/l,聚合物30mg/l。说明电絮凝与化学絮凝联合处理含聚采出水具有一定的可行性。3.含聚采出水电絮凝机理研究1)通过循环伏安图研究了电极电化学反应机理。测量、比较了多种电极材料的氧化还原电位,认为不锈钢-不锈钢(中间添加铁屑)电极还原电势较高,有利于氧化,作为第一级电絮凝电极对破乳有利。Al氧化还原峰电势较低,有利于产生Al离子,起电中和作用,作为第二级电絮凝电极有利于电中和、电吸附作用。2)通过XRD、场发射扫描电镜、红外光谱等表征手段,研究了电絮凝含聚采出水絮体形貌、结构特征、元素成分及相成分等微观形成机理,XRD确认电絮凝絮体产物主要成分为氢氧化铝；场发射扫描电镜发现与电絮凝水驱采出水产生的片状、柱状晶状结构不同,电絮凝含聚采出水形成的絮体为球团结构；红外光谱发现聚合物通过氢键与氢氧化铝结合。根据以上结果推测出电絮凝含聚采出水机理模型是在阳极产生铝离子,铝离子水解成为氢氧化铝,通过范德华力或氢键与水中HPAM发生吸附,形成球团结构,球团结构再通过HPAM相互连接成为团聚体。4.电絮凝与化学絮凝联合处理可行性研究通过制成套小型试验设备在油田现场试验,研究了现场条件下电絮凝与化学絮凝联合处理可行性。含聚采出水处理工艺流程：原水→电絮凝器→缓冲罐→加药混凝沉降器→缓冲罐→改性纤维球过滤器→出水。处理油田实际含聚采出水达到油含量小于5mg/L、悬浮物含量在小于1mg/L,聚合物含量小于15mg/l水平,达到了《碎屑岩油藏注水水质推荐指标及分析方法》(SY5329-94) Al级标准,可满足含聚污水回注低渗透油层要求。更多还原

【Abstract】 Coagulating sedimentation and filtration were wildly used in treatment of oilfield produced water. With the extension and application of polymer flooding in oil field, polymer flooding wastewater is complex and difficult to deal with. The water quality problems have become increasingly prominent. The existing conventional technology to deal with oil field produced water, such as coagulation sedimentation and filtration technology, has been unable to meet the requirements of normal production of oilfield. Therefore, to develop an effective, stable and cheap treatment and recycling technology has become an urgent problem to be solved. New technology to deal with produced water including polyethylene has a significant practical value and good environmental benefits. Fly ash coagulant with electric flocculation, coupled to the pulse electric flocculation electric neutralization, electric compression strength with fly ash adsorption of inorganic polymer coagulant multicore, enmeshment advantages combined, become a pulse electric flocculated colloid stability off-vortex coagulation reaction two-way settlement separation, are one of the effective treatment methods. In this paper, the preparation of fly ash coagulant, electrolytic flocculation treatment, mechanism of chemical flocculation and electric flocculation several aspects were conducted, main research content includes the following aspects:1. Preparation of coagulant using fly ash by solid state reaction1) The reaction conditions of coagulant preparation were studied. The conditions were changed to discuss the effection of stability include the mass ratio of raw materials, calcination temperature, calcination time, solid liquid ratio and pickling time. The mass ratio of ZnO/fly ash was0.3:1, and the mass ratio NaOH/fly-ash is0.6:1, calcination2h under600℃, solid liquid ratio is0.155g/mL, pickling time for2h, the product was poly aluminum silicate zinc iron (PAFZS) flocculant.2) XRD and FT-IR characterization were applied to probe the mechanism. The results showed that, ferric metasilicate and akluminium silicate were obtained. With the calcination temperature varied from200to650℃, the reaction was more and more suficient and benefit to the aggregation. FT-IR results presented that there was a narrow peak at about1053cm-1, which was the stretching vibration of-OH, such as Al-OH-Al, Fe-OH-Fe and Zn-OH-Zn. The transmittance became lower with more ZnO added, and the stability of PAFZS was increased. The peak at above444cm-1indicated the copolymerazation of Al3+, Fe3+, Zn2+and-OH.3) The properties of PAFZS were researched based on the turbidity and polymer content. The feasible pH range was5-7. The processing effects were good no matter the polymer concentration was lower(73.14mg/L) or higher(560mg/L). When the concentration was low, the PAFZS dosage was1000mg/L, the residual turbidity was below1NTU and the residual polmer concentration was under5mg/L. While the concentration was high, the PAFZS dosage was1400mg/L, the residual turbidity was below20NTU and the residual polmer concentration was under450mg/L.4) The surface tension and ζ potential change was studied to research the Flocculation mechanism of PAFZS. The results showed the acting force was elecr-adsorption. The ζ potential decreased with PAFZS dosage increased. The surface tension firstly declined and then increased with PAFZS dosage increased. Before lowest surface tension, the mechanism was the combination of electrical neutralization and adsorption volume sweep. After lowest surface tension, the mechanism was mainly adsorption volume sweep.2. Research of produced water containing polyethylene treated by the electrolytic flocculation1) Many materials were studied for electrolytic flocculation of polymer flooding wastewater. The polar materials were stainless steel-stainless steel and soluble aluminum anode, and the iron was filled in the middle. The electrolytic flocculation parameters were oil content, the turbidity and removal rate of polymer. In electric flocculation conditions of electric flocculation time20min, plate spacing2cm, electric flocculation voltage6v, initial pH value6, the pulse frequency0.3KHz, duty ratio0.4, the removal rate of polymer reached99.9%and the turbidity fell to0.62.2) The combination of electrolytic flocculation and chemical flocculation. Many factors were considered. Under optimum conditions, the oil content was below lmg/1, the suspended solid was below5mg/l and polymer30mg/1. The results indicated the feasibility of combination.3. Mechanism research of electrolytic flocculation1) The electrochemical reaction mechanism was studied by cyclic voltammetry. The redox potential of polar materials were measured and compared. The reduction potential of stainless steel-stainless steel higher, and benefit to oxidation and demulsification. The redox peak of aluminum was lower, and good to produce Al3+. As secondary electrode material, Al3+was conductive to electro-neutralization and electro-adsorption.2) XRD(x-ray diffraction), field emission scanning electron microscopy (fsem) and infrared spectroscopy characterizations were carried out. From the results, the electrotic flocculation mechanism of polymer flooding wastewater was analyzed. The XRD indicated the product of Al(OH)3. From the FSEM results, it could be found that the product of electrolytic flocculation were of different structures. FT-IR presented the hydrogen bonding between polymer and Al(OH)3. In conclusion, the mechanism was as follows:aluminum ion generated in the anode, and hydrolyzed to Al(OH)3. The Al(OH)3adsorbed HP AM by Vander Waals force or hydrogen bonding, and then formed pellets. Finally, these pellets connected together and aggregate.4. Feasibility study of electrolytic flocculation and chemical flocculation combinationThe oilfield test was carried out through simulation test equipment to study the feasibility of electrolytic flocculation and chemical flocculation combination. Treatment process of the produced water:raw water→electrical flocculator→buffer tank→dosing coagulation settler→the buffer tank→modified fiber ball filter→water. In produced water after treatment, oil content is less than5mg/L, the suspended solids content is less than1mg/L, polymer content is less than15mg/L levels, produced water after treatment reached A1standard of (SY5329-94).更多还原