关键词： 泥石流   颗粒流   颗粒分选   流态   流-固耦合(CFD-DEM)  

摘要： 颗粒分选普遍存在于由不同粒径组成的泥石流中,其中粗大颗粒更多地聚集在自由表面,而相对细小的颗粒则集中在底部,这种现象被称为泥石流的逆分选,它是泥石流运动-堆积过程中的一个突出特征,并对整个流动的动力学特性具有重要影响。颗粒分选已在干颗粒流(碎屑流)中得到了广泛地研究,其中忽略了颗粒间隙的流体对颗粒分选的过程产生的影响。而在泥石流中,颗粒间隙中充满了流体(泥浆体),固相和液相之间的相互作用非常强烈,因此可能会影响分选行为,具体取决于固-液混合物的材料特性。本文致力于研究泥石流(颗粒-流体混合流体)中的颗粒分选机理,特别是微观力学机制以及在不同流体环境中流体-颗粒间相互作用对颗粒流的局部流变学的影响。基于此,我们采用流-固耦合的方法(离散元法DEM耦合计算流体动力学CFD,CFD-DEM)进行了大量的两相流数值模拟研究。在重力作用下的两种粒径组成的颗粒流沿着粗糙面完全浸没在流体环境中,数值模拟结果表明,流体主要以两种方式影响分选,浮力减小了将大颗粒推向表面所需的颗粒接触力,而垂直于基底的粘滞阻力可以忽略不计,即使黏度很高,也不会直接阻碍大颗粒的向上运动。相反,沿着颗粒流相反的流向作用的粘滞阻力引起不均匀流动分布的形成,例如沿着流体的深度方向局部剪切速率降低,这种局部剪切力的降低导致颗粒分选的减弱。通过粘-惯性模型定义了在各种环境流体粘度(即从空气到水、泥浆)中的颗粒流的流变性,该模型可以反映颗粒的惯性和粘性耗散对其运动的影响。通过考虑颗粒的不同粒径将该模型进行改进,推广至含有两种粒径的混合物中。此外,模拟结果显示,具有不同粒径的混合物的局部有效摩擦力和体积分数可以从单一粒径的颗粒流的流变学中近似得出,而有效体积摩擦力与竖向分选的过程和状态无关。在剪切率和围压的控制下,结合流向速度反馈,通过观察平面剪切流的几何形态,可以看出流体粘度和密度对分选的影响和非均匀流中流变性的影响无关。粘度对分选的影响分为两种形态,在低粘度情况下,除非颗粒和流体的相对密度或内在条件发生变化,否则颗粒分选不取决于粘度,并且保持常数。当流体具有高粘度时,颗粒分选随着粘度呈线性变化。当流体的密度接近颗粒的密度时,由于浮力而导致颗粒分选减弱。粘性作用主要通过降低颗粒运动来实现,自由运动受到的粘滞阻力抑制了它们在混合物中的渗透和迁移的能力。总体而言,流体的作用可以总结为一套经验的尺度关系来预测在不同流态下的分选速度。

摘要： The formation of hydrothermal ore deposits depends on both the fertility of the involved fluids and the precipitation mechanism. The groundwork for understanding these two aspects is best laid by a detailed mineralogical and geochemical investigation, and supplemented by a geological-framework-considering qualitative model. However, in order to fully understand the involved processes, and to verify the qualitative model, an at least semi-quantitative thermodynamic model is essential. This requires the time-consuming task of compiling, and estimating where appropriate, thermodynamic data for all important mineral species involved. In this thesis, this approach is applied to various aqueous settings from ambient to metamorphic conditions. The thesis is subdivided to cover four different settings: (I) groundwater brines, (II) the fertility and evolution of basement brines and the process of fluid mixing, (III) As- and Ni- bearing hydrothermal brines and the process of fluid reduction and (IV) metamorphic fluids and the process of hydrothermal Ni-remobilization under reducing conditions as well as cooling of Sb-rich fluids. (I) Surficial water can drastically change its fluid composition through fluid-rock interaction. This is an important process that occurs anywhere between surficial and deep-seated crustal settings. Furthermore, ligands such as Cl play a vital role in the ability of such fluids to mobilize elements. At Buggingen, SW Germany, groundwater partially dissolved evaporitic salts and subsequently reacted with mafic magmatic dikes. Progressive desiccation due to H2O consumption by clay mineral formation and swelling, the fluid ultimately reached the point of halite saturation. (II) Surficial fluids can infiltrate deeper into the crust and form fertile hydrothermal fluids, and if certain conditions are met, form hydrothermal veins. In the study area of the Black Forest, this occurred over the past ~300 Ma in the basinal and rift-related setting of SW Germany.

关键词： N80钢   CO2腐蚀   O2腐蚀   腐蚀产物膜特征   原位电化学测试  

摘要： 近年来,随着稠油油藏开发的推进,对稠油油田开发提出了更高的要求。注多元热流体吞吐技术能有效提高稠油采收率,有望成为稠油油田开发的主要手段。但注入的多元热流体成分主要由高温高压的水蒸气、CO、N及少量O等组成,高温高压CO和O共存的腐蚀环境极易导致油井管腐蚀失效,阻碍了注多元热流体技术的推广。因而油井管材在高温高压CO与O共存环境中的腐蚀机理成为腐蚀控制领域亟待解决的科学问题。由于O腐蚀的快慢主要受溶解氧在扩散层中的扩散速度控制,而流速不仅影响物质传质扩散过程,还会影响表面扩散层的厚度及溶解氧在扩散层中的扩散速度,因此研究流体流速对油井管在多元热流体CO和O共存环境下腐蚀行为的影响具有重要实际意义和理论价值。本文主要以常用油井管材N80钢为研究对象,利用自制的高温高压多相流冲刷腐蚀实验装置,进行多元热流体环境下的腐蚀模拟实验,结合原位电化学测量和现代表面分析等技术手段,研究流体流速对N80钢在高温高压CO和O共存环境下腐蚀行为的影响以及该环境下腐蚀产物膜的演变过程。获得主要结论如下:（1）0.5 m/s流速时,N80钢在52%CO-2.9%O共存环境中的腐蚀速率远大于在2.9%O和52%CO单独存在时的腐蚀速率之和,共存环境中试样表面腐蚀产物膜为双层膜结构,外层腐蚀产物主要为疏松多孔的FeO和Fe OOH,对基体基本没有保护作用,内层腐蚀产物主要由FeCO晶体构成。结合热力学计算可知:在此环境下N80钢阳极反应过程包括Fe的阳极溶解过程、Fe与HCO直接反应形成FeCO的过程以及Fe被足够O氧化成Fe的过程,阴极反应过程同时包括酸性条件下吸氧和析氢反应。（2）静态条件下,无局部腐蚀出现,腐蚀产物膜为FeCO单层膜结构,腐蚀产物膜层较致密。非静态条件下,试样表面腐蚀产物膜为双层膜结构,外层腐蚀产物膜由红褐色FeO和Fe OOH构成,内层为较致密的FeCO晶粒。随着流速的增大,部分疏松的腐蚀产物脱落使得膜层厚度减薄。（3）流体流速由0 m/s增加到0.5 m/s,N80钢腐蚀168 h时的腐蚀电流I减小,阳极Tafel斜率b变大,阴极Tafel斜率b变小,极化电阻R、膜层电阻R_f、电荷传递电阻R_t和扩散电阻W均增大;流体流速由0.5 m/s到2.0 m/s,I变大,b基本不变,b变小,R、R_t和W均变小。流速由0 m/s增加到0.5 m/s,氧在界面处扩散层厚度由94.16μm减薄为2.84μm,吸氧反应速度加快,使试样表面快速形成较厚的Fe的氧化物,导致R、R_f、R_t和W均变大。流速由0.5 m/s增加到2.0 m/s时,氧在界面处扩散层厚度进一步减薄,从2.84μm减小到0.62μm。但由于腐蚀产物膜减薄使R、R_f、R_t和W均变小。（4）流速为0.5 m/s时,N80钢多元热流体CO和O共存环境下腐蚀产物膜演变机制:腐蚀初期,N80钢基体快速溶解,试样表面局部迅速形成少量FeCO及铁的氧化物,使电化学阻抗中出现低频感抗。随着腐蚀的进行,试样表面腐蚀产物逐渐增多,腐蚀7 h时,试样表面被腐蚀膜完全覆盖,感抗L消失,阻抗谱Nyquist图由两个容抗弧构成。腐蚀24 h时阻抗谱Nyquist图低频出现扩散阻抗。随着腐蚀继续进行,24 h后,试样表面产物膜厚度增大,膜层电阻R_f、电荷传递电阻R_t和扩散电阻W均增大。

关键词： 深层-超深层碎屑岩   构造成岩作用   裂缝表征   石英桥  

摘要： 深层-超深层油气勘探潜力大、领域广,但与浅层相比,深层储层强压实、多类型、非常规、控制因素复杂,天然裂缝往往对深埋储层物性的改善至关重要。然而,并非所有的天然裂缝都能成为流体通道,被胶结物完全充填的裂缝只会成为油气疏导的屏障。因此,需要深入探索构造应变与流体活动的相互作用机制及其产生的储层效应,加强构造成岩作用研究。库车前陆冲断带天然裂缝系统受高温压环境、构造演化及其制约下流体-岩石相互作用的多重叠加改造,构造应变-流体活动相互作用的层次性及主控因素尚不明确。同时,缺乏针对构造应变-流体活动相关地质现象的具体分析,未能深入认识储层裂缝有效性保存和改造的物理/化学机制。针对上述问题,本文以库车前陆冲断带白垩系砂岩储层有效裂缝为研究目标,开展深埋碎屑岩储层的构造-流体环境研究。针对不同构造部位、不同裂缝系统的砂岩开展取样测试,通过分析砂岩裂缝石英桥的流体包裹体均一温度变化序列,重建裂缝张-闭过程;通过微区原位氧同位素分析,揭示裂缝成岩流体来源及效应;通过裂缝有效性定性和定量分析,阐明深埋裂缝有效性的保存及改造机制,最终建立有效裂缝发育模式。结果表明:1)库车前陆冲断带白垩系砂岩特定裂缝系统中发育石英桥,石英桥生长主要受温度控制,定量分析认为克拉苏构造带白垩系石英桥最多可跨越1mm宽裂缝;2)垂直褶皱轴裂缝系统在晚期快速深埋期间张开,平行褶皱轴裂缝系统在晚期快速深埋-抬升期间张开;3)平行褶皱轴裂缝张开期间,古近系蒸发岩流体(富集O)在超压、重力和侧向挤压作用下运移至白垩系裂缝中,石英桥沉淀过程中发生O交换,导致石英桥氧同位素与围岩中石英氧同位素组成的差异;4)石英桥、晚期未充填和剪切复活在深埋强挤压环境下保存、改造储层裂缝有效性,有效裂缝可用最大和最小主应力间差值、裂缝倾角、裂缝与最大水平主应力间夹角、临界伸展系数和临界滑动系数确定,其中临界伸展系数和临界滑动系数的阈值分别为0.7和0.6。基于上述认识,本文建立了库车前陆冲断带深层白垩系砂岩储层有效裂缝的发育模式。这对于推进构造成岩作用相关理论研究和实际应用,指导深层油气储层评价和预测具有重要的现实意义和理论价值。

关键词： 完井   油井管材   高温高压   氯化钙腐蚀   甲酸钾腐蚀  

摘要： 从钻开油层到油井投入生产的所有环节都离不开完井液的使用,与此同时,这导致完井液频繁地与井下油井管材接触。随着油田深井、超深井开发过程中一体化管柱的使用,完井液中常常含有O、CO气体或Ca、K、HCO以及Cl等腐蚀性介质,导致普通材质的油井管材更易发生腐蚀反应,导致壁厚减薄、断裂,给油气田开发带来极大的安全隐患和经济损失。本文针对常用油井管材所遇到的腐蚀问题,模拟多元热流体腐蚀介质环境,采用失重法分别测量不同密度完井液(氯化钙、甲酸钾)、环境温度、流速条件下P110钢和TP140V钢的腐蚀速率,结合扫描电镜(SEM)、能谱分析(EDS)和X射线衍射仪(XRD)对两种材料的表面腐蚀形貌和产物成分进行测量,分析完井液对管材腐蚀成因及影响因素。得到的主要结论包括:(1)在多元热流体环境中,氯化钙密度会影响溶液中溶解氧的含量,进而改变油井管材的腐蚀速率;甲酸钾密度增大,一方面会导致溶液中溶解氧含量线性下降,减缓材料腐蚀,但另一方面导致溶液的导电性增强,促进材料腐蚀,且促进作用大于抑制作用,使得P110钢和TP140V钢的腐蚀速率均随甲酸钾密度的增大而增大。(2)在氯化钙溶液中,P110钢在临界温度150℃时腐蚀速率达到最大值,随着温度升高,腐蚀产物膜的有效性提高,对金属基体起到了保护作用;在甲酸钾溶液中,P110钢和TP140V钢的腐蚀速率随温度升高而出现相反的腐蚀规律,这与不同温度下材料在甲酸钾溶液中生成的腐蚀产物膜的成分、致密性密切相关。(3)在多元热流体环境中,流速的增加,一方面使得溶液中溶解氧含量增多,加快腐蚀反应,生成的腐蚀产物随之增多,另一方面较大的流速使得材料表面腐蚀产物脱落,腐蚀性介质直接与金属基体接触,腐蚀加剧。这两方面因素的协同作用下,导致P110钢和TP140V钢在完井液中的腐蚀进程加快。

关键词： Waste-to-energy   Assessment   Environmental impact   Emissions   Sustainability   LCA  

摘要： Combustion can concentrate phosphorus (P) from poultry litter into an ash product that is easier to transport for land application. This was the first life cycle assessment (LCA) study to investigate the efficacy and sustainability of a fluidized bed combustion (FBC) system using poultry litter to heat poultry houses and produce electricity, in the United States, to replace liquid propane gas (LPG) and natural gas (NG) use. The 'Baseline scenario' used results from a 16-month FBC monitoring study, and an 'Improved scenario' based on an increased biomass feed rate (0.246 tons/h), increased run-time (6720 h/y), and net positive electricity production. In the Baseline scenario, climate change potential was 32% and 44% lower than use of LPG and NG, respectively, for poultry house heating, but the low electricity production from the FBC system resulted in net electricity import and lower sustainability compared to LPG use in 12 of the 18 impact categories. The Improved scenario had 48-98% less environmental impacts than the Baseline scenario in the 18 categories. The sensitivity analysis showed that a 10% change in the electricity input for FBC operation resulted in the highest average change (4.8%) in the 18 impact categories, indicating the necessity of a net positive electrical energy output from the FBC unit for increased sustainability. The results also highlighted the impact of the replacement heating fuel type, as replacing NG through poultry litter combustion had a greater impact than replacement of LPG. (C) 2020 The Authors. Published by Elsevier Ltd.

关键词： 热流体   水化学   环境同位素   形成年龄   地热系统  

摘要： 利用大量的地热流体化学成分及环境同位素(δD、δ18O、14C)测试数据,深入分析了隆起山地构造对流型、沉降盆地传导型地热流体的化学特征及分布规律,进而对地热流体的环境同位素分布特征及形成年龄进行了梳理总结,得出了明确的结论。结果表明:隆起山地构造对流型地热田地热流体主要以断裂上升泉的形式出露,分布于西秦岭-祁连造山带,补给来源为当地及周边大气降水入渗,地热流体形成年龄一般小于5000~30000 a,水质较好,属“开启型”的地热系统;热储层岩性、断裂规模及水热循环方式和深度等明显控制着地热流体化学类型、环境同位素特征和形成年龄。沉降盆地传导型地热田地热流体主要以管井开采的方式出露;热储埋藏深度小于1600m的地热井,地热流体补给来源为当地及周边大气降水入渗,形成年龄一般小于5000~30000 a,水质相对较好,属“半开启-半封闭型”的地热系统;热储埋藏深度介于1600~2600 m之间的地热开采井,主要为地质历史时期逐步形成的“古水”,水化学类型复杂且水质较差,地热流体形成年龄介于30000~50000a,属“封闭型”的地热系统;热储层岩性、埋藏深度、地下水在岩层中的滞留时间与循环深度等明显控制着地热流体化学类型、环境同位素富集程度和形成年龄。

关键词： Coal ash size fractions   PAHs   Water-soluble organic carbon   PAHs emission factors   Benzo[a]pyrene equivalence concentration  

摘要： The comparison of fly ash generated from lignite combustion in a thermal power plant Kolubara A (Veliki Crljeni) and bottom and fly ash from coal waste combustion in a semi-industrial fluidized bed boiler (Vinea) was performed as the function of particle size. The average total concentrations of the 16 EPA priority PAHs in ash fractions are 0.49 mg kg(-1) of ash (thermal power plant) and 17.48 mg kg(-1) of ash (fluidized bed boiler). The sum of 3- and 4-ring PAHs accounts for more than 93% of overall PAHs concentration, and the most abundant among them is fluoranthene. The portions of PAHs groups defined based on their physico-chemical properties, as obtained from quantitative structure-activity relationship (QSAR) models included in the Vega platform, were determined. These portions, emission factors, and benzo[a]pyrene equivalence concentrations were further on used to estimate the potential environmental impact of ash disposal. The PAHs emission factors are higher compared to values in the air pollutant emission inventory guidebook of the cooperative program for monitoring and evaluation of the long-range transmission of air pollutants in Europe (EMEP/EEA). The overall emission factors of 16 PAHs for combustion of lignite and coal waste are determined to be 0.15 and 249.97 mg kg(-1) of fuel, respectively. Based on the ratios of benzo[a]pyrene equivalence concentrations of each ash and correspondent fuel, the disposal of fly ash from the cyclone of fluidized bed boiler represents the highest risk to the environment among tested ashes. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Hot flue gas   Corrosion   Pressurized oxy-fuel combustion   Duplex stainless steel  

摘要： The selection of constructional material of flue gas components is crucial for the successful deployment and long-term safe operation of the newly developed oxy-fired pressurized fluidized bed combustion plants. In this study, the corrosion performance of a candidate steel, duplex stainless steel 2205 (DSS 2205) was investigated in simulated flue gas mainly composed of CO2/H2O/O-2/N-2/SO2/HCl with a total pressure of 1.50-1.64 MPa at 270-320 degrees C. The oxidation kinetics of DSS 2205 followed parabolic law, and the formed surface oxide was a double-layer structure with outer Fe-rich oxide and inner Cr-rich oxide. Besides general oxidation, SO2 and HCl-induced pitting also occurred. Increasing temperature led to enhanced general oxidation and accelerated pitting. Extending exposure duration resulted in increased pit density, but did not noticeably affect the maximum pit depth. These results indicate that the steel is a promising candidate for further pilot- and industrial-scale assessments.

关键词： 水化学成分   地热流体   勘察技术   水质分析   成因环境   水质数据  

摘要： 在近几年的发展中,地热是一个热门的讨论话题,同时也受到我国相关部门的重视,目前相关的勘察技术和手段比较多,而且功能也比较全面。在开展相关工作的过程中,应该根据实质情况对水质数据做出分析,再采取相应的处理方法,本文对当前水质分析在热水勘察中的应用做出分析,以供相关人员参考。