在石油工业中，未经处理或只经过初步处理的原油、矿化水在管道中共同流动的情况十分普遍。在油田集输系统中，油水两相混输工艺的采用较油水分离后再分别输送的工艺具有明显的经济效益。通常油田集输管网的投资约占地面工程总投资的40%，集输能耗甚至占生产总能耗的一半以上，而对于边际油田或海洋油田，建设及运行管理的费用将更加庞大。因此，如果采用多相混输方式，将井口产出液通过混输管道输送至后方或陆上处理场集中处理，则可大幅度地降低一次性工程投资以及后期运行成本。并可使一些在分输工艺技术条件下不具备开采价值的边际油田获得经济有效的开发。 由于原油中含有胶质、沥青质及固相小颗粒等天然乳化剂物质，含水原油在开采和输送过程中，极易生成稳定的油包水乳状液。目前世界上开采的以乳状液形式为主的原油接近原油总产量的80％，而我国的石油资源多为易凝高粘原油，如辽河、渤海稠油等，当这些稠油与水形成油包水乳状液后，其粘度大大升高且流动性极差。同时，乳状液的流动往往呈现出非牛顿流体的特性，这些因素都增加了输送过程的难度。因此，如何准确的掌握稠油包水乳状液的物性特点，科学的预测管内稠油-水两相流动的规律，对管道的安全和经济运行具有重要的指导意义。 本文通过开展基于相似性分析的高粘基础油-水、现场稠油-水两相流动对比实验研究，比较了两者流动规律的区别与联系，包括流型、压降、尤其是相转换规律的异同点。发现并研究了高粘油-水、稠油-水流动过程中的特殊现象——局部相转换现象，比较了局部相转换前后压降及有效粘度的变化规律，并分析了其产生的原因。由此得出结论，稠油-水管流的相转换过程，实质上偏离了通常意义上的反相，即连续相与分散相之间的相互转换，而是一种受稠油-水乳化特征影响的相转换过程。并由此深入思考，提出：一方面，需要从机理层面进一步分析影响油水体系反相过程的本质；另一方面，需要深入认识乳化后稠油包水乳状液的物性及流变特性，由此进一步揭示稠油-水两相管流的流动特性及规律。（基于上述研究成果，已发表3篇高水平学术论文，参见本附件1中代表性成果3-5。） 一方面，从机理层面进一步分析影响油水体系反相过程的本质。结合对分散相液滴生成的微米级界面特性实验研究，将整个液滴生成过程划分为四个阶段，并选取液滴生成的第二、三阶段，作为微观液蒲公英的描写-液聚并实验的研究对象。通过改变油水体系的液-液聚并特性，从机理层面分析了液-液聚并特性对油-水反相过程的影响。由此进一步揭示：油水体系中微观液-个人问题液聚并特性的改变，是影响油水体系反相过程的本质原因。（基于上述研究成果，已发表2篇高水平学术论文，参见本附件1中代表性成果1-2。）小学数学教育叙事 另一方面，稠油-水管流流动规律研究的深入，需要建立在更深入的稠油包水乳状液物性及流变规律研究基础上。而实验室内对稠油包水乳状液物性及流变性的研究，需要以可重复的乳状液制备过程为依托，以此保证所获研究成果的准确性。因此，本文首先总结了可重复的乳状液制备方法，并系统分析了影响油水乳化特征的机理。李家政 结合单相流体搅拌剪切的相关成果，定性分析了影响油水乳化特征的关键机理，并得出结论：若可以再现油水乳化过程的剪切历史，复杂的油水乳化过程实质上是具有较高可重复性的。同时，分析了影响乳化过程的关键因素，并重点研究了制备温度、搅拌时间等因素对乳状液制备过程的影响，结合对搅拌过程输入扭矩的时时监控，确定了油水乳化过程中所经历的剪切历史，是影响油水乳化特征的本质。 以可重复的乳状液制备过程为实验基础，系统分析了油水乳化特征对形成稠油-水分散体系宏观流变特性及微观分布特性的综合影响。这其中结合显微镜观察及后期的图像处理与统计，实现了对乳状液微观特性的分析与测量。最后，通过引入液滴雷诺数，将剪切率（影响宏观流变特性的主要因素）及微观液滴分布（表征微观分散特性的因素）原本彼此孤立的影响因素有机的结合起来。验证表明，对呈非牛顿性的稠油包水乳状液体系，液滴雷诺数能够很好的表征宏观与微观影响因素对其物性及流变特性的共同影响。 同时，针对现有乳状液粘度模型没有涵盖微观特性影响的局限性，结合上述研究成果，以有效介质理论为基础，在经典Pal & Rhodes乳状液粘度预测模型基础上，进一步拓展了其非牛顿因子的物理意义和影响因素，加入了微观液滴分布对非牛顿特性的影响，由此提出了包含宏观因素影响——剪切率、含水率、连续相/分散相粘度，及微观影响因素室内设计论文——微观液滴分布共同影响的机理模型。结合现场稠油、水取样乳状液验证分析，结果表明，该模型对中、高含水率时的非牛顿稠油包水乳状液体系具有很好的预测精度。（基于该创新点，在国家级期刊《化工学报》上发表学术论文1篇，在国家级期刊《石油学报》上发表学术论文1篇（发表日期2010.11搞笑小剧本），参见博士论文在学期间研究成果。） 此外，针对非牛顿稠油包水乳状液粘度测量中发现的问题，即乳状液在表现出剪切稀释性的同时，仍表现出随剪切时间延长粘度下降的依时特性。首次探究了非牛顿型稠油包水乳状液的触变性规律，系统分析了宏观及微观诸因素对触变性的影响，讨论了所具触变性的可恢复性特征，并依据上述特征建立了表征该非牛顿乳状液触变性的预测模型。最终，提出宏观剪切作用同微观分布特性间的相互作用与影响，是油水体系呈现出触变性的本质。 礼金一般给多少综之，论文采用实验研究和理论分析相结合的方法，从更深层次研究了油-水混合液物性及流动规律这一看似普通的课题；对宏观与微观特性间的相互作用的分析与把握，始终贯穿于整个论文的研究思路。论文研究成果具有较好的理论深度及工程应用价值，取得了较好的创新。 |
In petroleum industry, it’s a common phenomenon that crude oil and water two phas flow together in the transporting pipeline. Since crude oil usually contains some natural emulsifiers as asphaltene, resin and small particles, it’s easier to form water-in-crude oil emulsion during drilling facility and transporting process. In China, heavy crude oils take a huge percentage of its total oil production. Even the transportation of single heavy oil pha is a difficult task, however, it’s discovered that it’s even harder when heavy oil and water pha joined together and result in a stable water-in-heavy crude oil emulsion. The apparent viscosity of the formed emulsion is greatly incread, while it usually appears to be a non-Newtonian fluid. As a result, it’s esntially important to obtain the physical properties and flow characteristic of the formed emulsion, which would be the guidance for the management of multipha pipeline. Through the experiments of high viscosity mineral oil-water and heavy crude oil-water two pha flow, flow characteristic such as flow patterns, pressure drop and pha inversion phenomenon are compared. It’s discovered that the pha inversion phenomenon during heavy crude oil-water flow is different from its theoretical definition. Instead, it’s obviously influenced by the emulsification of oil and water pha. Bad on upper understanding, it’s strongly recommend to further investigate the key point of pha inversion and properties of water-in-heavy crude oil emulsion, which could help to gain more understandings about their pipe flow character. (Publications 3-5 in appendix 1 are bad on upper understanding.) Obrvations on single drop formation from a capillary tube are carried out, while four different stages of the drop formation are identified. The attaching and detaching forces which act on the drop during formation are calculated bad on experimentally measured parameters. Stage two and three is recommended and chon for further coalescence experiment. Binary coalescence of water drops forming through capillaries in an immiscible stagnant oil pha is studied and coalescence rate is changed with the add-in of glycerol as a third material but not a surfactant. The reduced water drop coalescence times in the prence of glycerol are responsible for the decread water fraction required for pha inversion of the organic-aqueous dispersion. (Publications 1-2 in appendix 1 are bad on upper understanding.) The preparation of water-in-heavy crude oil emulsion is investigated, and main attentions are focud on the repeatable preparation method or process. It will help to support the following rearch on the shearing thin and thixotropic behavior of the emulsion. It’s then confirmed that the shear rate is the key parameter and the preparation process can be repeated if the shearing history is the same. Droplets are obrved through the microscope and drop size distributions are obtained statistically. Particle Reynolds number (Nre,p) are introduced and studied, while it’s found that it can reflect the influence of shear rate in macro scale and drop diameter in micro scale together on the apparent viscosity of emulsion. Since the published viscosity prediction models for emulsion haven’t considered the influence of drop size distribution, and previous results about drop size distribution have shown its importance, an improved viscosity prediction model is carried out bad on the viscosity prediction models of Pal & Rhodes. The effect of drop size distribution is considered and added in the non-Newtonian coefficient. Comparison results show that the improved model can predict the viscosity well at moderate and high water fraction. (One publication in Journal of Chemical Industry and Engineering (China) are bad on upper understanding, while another paper has been published in Acta Petrolei Sinica 2010.11.) The thixotropic behavior of non-Newtonian water-in-heavy crude oil is firstly investigated and the effects of water fraction, shear rate, temperature, drop size and etc. are studied. As well, the recovery behavior is checked during the experiment. It’s analyzed and concluded that the appearance of thixotropy is due to the variation of drop size distribution. All in all, the drop size distribution in micro scale is the key parameter which would affect, but also would be affected by the rheological behavior of the emulsion in macro scale. 老公英语怎么说In conclusion, experimental and theoretical investigations are combined to further analyze the physical properties and flow dynamics of the heavy crude oil-water mixture. The interaction and mutual impact of the appearance properties in macro scale and deeper characteristics in micro scale are considered and discusd throughout the disrtation. The achievements in prent disrtation will have profound effect both theoretically and practically. |
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