含蜡原油管道清、防结蜡技术

在管道输送含蜡原油的过程中,由于原油的物性,即原油的内在因素,和外界环境因素的影响,输送过程中会产生操作上的问题,有时会严重影响生产的进行。本文针对目前我国原油输送管道所存在的含蜡问题,分析含蜡原油管线结蜡机理和影响因素,提出了常用于输油管道的清防蜡化学药剂。     

含蜡原油管道结蜡机理及清蜡技术研究

在管道输送含蜡原油的过程中,由于原油的物性,即原油的内在因素,和外界环境因素的影响,输送过程中会产生操作上的问题,有时会严重影响生产的进行。针对目前我国原油输送管道所存在的含蜡问题,分析含蜡原油管线结蜡机理和影响因素,提出了常用于输油管道的清防蜡化学药剂。     

原油组成对原油管道结蜡规律的影响

利用旋转式动态结蜡装置,对不同组成的人工油样(胶质和沥青质含量不同或蜡含量不同)进行了不同条件下的实验研究.通过对管壁沉积物取样并利用差式扫描量热法(DSC)和四组分法进行分析,探究了不同原油组成对结蜡的影响规律.结合胶质和沥青质在结蜡过程中的作用机理,发现胶质和沥青质的存在虽然总会削弱蜡分子的迁移动力,阻碍蜡分子的沉积,但在含量较小时会协同蜡分子的沉积作用,而当含量较大时会以粘壁的形式附着于管壁.对蜡含量不同原油的结蜡规律研究发现:原油所含蜡分子的碳数越高,结蜡层中的蜡含量就越少.但由于碳数较高的蜡分子具有相对较长的碳链,更容易与原油中的胶质和沥青质发生共晶作用,故更易与胶质和沥青质一起沉积于壁面.     

石蜡无催化剂氧化工艺研究

研究了石蜡在一种氧化引发剂作用下的氧化反应工艺,考察了反应温度、空气量、反应时间、引发剂的用量、引发温度、引发时间等对石蜡氧化的影响。结果表明,石蜡氧化的最佳工艺条件是:反应温度140℃左右,反应时间6.5～7 h,引发剂用量2.0%,引发温度160℃,引发时间30 min,空气量0.5～0.75 m3/(h.kg)。在此条件下,制备出了具有良好性能、符合产品性能指标的氧化石蜡。     

Investigation of thickness and wax content of wax deposits in polyethylene pipe using a flow loop

In this study, the thickness and wax content of wax deposits were found to be thinner and lower in the polyethylene (PE) pipe than in the stainless steel (SS) pipe using a flow loop apparatus. The diffusivity of wax, radial thermal gradient, and wax precipitation rate in the PE and SS pipes were calculated and compared. It was found the diffusivity of wax in the PE pipe was higher and tended to enhance the wax deposition in the PE pipe, while the radial thermal gradient and wax precipitation rate were lower in the PE pipe and had the opposite effects. These factors are shown to be comparable with each other and the effect of the thermal gradient dominates the mass flux of wax from bulk to the oil-deposit interface and into the deposits finally, thus causing differences in thickness and wax content of deposits between the PE and SS pipes.     

油蜡混合物的性质研究

油蜡混合物性质的研究是制定清管方案的基础。目前,一些实验通过原油和白蜡掺混制备混合物进行模拟,但物性与实际管道蜡沉积物有所差别。为了使研究结果更贴近实际,以管输原油和球前蜡沉积物为实验原料。通过研究熔蜡温度对油蜡混合物析蜡特性、显微特性和屈服特性的影响,发现熔蜡温度越高,蜡晶在混合物中溶解越充分,微观条件下混合物的长径比增大,盒维数减小,导致低温下相同条件油蜡混合物的强度降低屈服应力减小。从宏观和微观角度对油蜡混合物的性质进行分析,对于制定清管方案具有一定意义。     

仙水沥铅矿床地质特征及成矿条件分析

仙水沥铅矿属于火山岩中—低温热液矿床。矿体受东西向破碎带构造所控制,呈脉状或透镜状矿体产出,矿石类型多呈浸染状。矿石有用组分为Pb、Ag等,比较单一。黄铁矿、方铅矿呈散状及细脉状浸染在次流纹斑岩中。次流纹斑岩是形成热液运移、沉淀的良好场所。     

沥青质对蜡结晶和原油胶凝行为影响的研究

简要介绍了蜡结晶和原油胶凝的过程,介绍了国内外沥青质对蜡结晶和原油胶凝行为影响研究的,简要分析了沥青质对蜡结晶和原油胶凝不同影响的表面现象和内在原因,并在此基础上横向比较了各种说法的不同结论和内在机理解释,揭示了沥青质与蜡产生协同作用并影响原油流动特性的机理。     

Settling and re‐entrainment of wax particles in near‐gelling systems

Under near‐gelling conditions, the precipitated wax particles can settle down due to gravity and form a bed at the bottom of the pipeline. During restart, the settled waxy bed can increase the pressure drop significantly, and the necessity for pigging and/or addition of chemicals has to be determined to re‐entrain settled wax particles. A laboratory‐scale flow loop, first of its kind, has been built and used to understand the settling and re‐entrainment behavior. The experimental results confirmed the settling of precipitated wax in a pipe under quiescent conditions when the oil temperature falls between wax appearance temperature and pour point. During restart, complete re‐entrainment was attained after reaching a critical flow rate. Solid transport models were able to predict reasonably good results in agreement with experiments. This work emphasizes the importance of understanding the behavior of waxy crude oil during production shutdown and design appropriate startup strategies. © 2017 American Institute of Chemical Engineers AIChE J, 64: 765–772, 2018     

油田用高效除蜡剂的研究

研制了一种适合油井使用的弱碱性除蜡防蜡剂,其主要成分为十二烷基苯磺酸钠?十二烷基磺酸钠?焦磷酸钾?硼砂?脂肪醇聚氧乙烯醚?苯甲酸钠和苯并三氮唑,探讨了各种因素对除蜡效果的影响。结果表明,除蜡剂的最佳使用温度65℃,最佳除蜡时间2 h,最佳浓度为浓缩液的0.2倍。     

水平管内油水两相流流型转换特性

以高黏度的油和水为工质,在内径为25.7 mm,长52 m的水平不锈钢油水两相流实验环道内对油水两相流流型及其转换特性进行了实验研究.根据实验结果定义了不同流动条件下出现的流型,绘制了流型图.对影响油水两相管流流型转换的各种因素进行了综合分析,利用量纲分析的方法得出了流型转换的准则关系式,并提出了一个较为准确的有关油水两相管流中反相临界含水率的计算相关式.     

一株嗜蜡微生物的筛选及初步性能评价

以52#石蜡为唯一碳源,从延长油田采油污水和炼油厂活性污泥中分离出4株嗜蜡微生物YC-1、YC-2、YC-3及YC-4,35℃、135r.min-1摇床培养12 d时降蜡率分别达到11.12%、9.21%、9.29%及7.84%。在培养时间筛选实验中,求得嗜蜡微生物YC-1菌株在35℃、135 r.min-1摇床培养10d时,除蜡率达到最大。对降蜡能力最优的嗜蜡微生物YC-1进行降蜡摇瓶实验,对其降蜡产物进行色谱分析,显示嗜蜡微生物YC-1能对52号石蜡有效降解。YC-1处理原油显示其对原油有降蜡、降凝、降粘的作用。     

管道结蜡层温度分布计算研究

通过对试验环道上测试段相关数据的测试,对比分析测试段管壁有沉积物和无沉积物时测试段管壁内温度分布的不同表达式,根据能量方程建立了无量纲温度分布方程,利用贝赛尔函数推导出原油在层流状态下沉积层表面温度分布、沉积层热流密度、油流温度分布等相关温度场的计算公式,为研究蜡沉积规律,定性分析管路结蜡层厚度和制定合理的清管方案奠定了理论基础.     

油水两相流蜡沉积研究进展

蜡沉积研究中,油水两相蜡沉积的研究已成为研究重点,但对此领域的研究还处于起步阶段。本文系统阐述了国内外蜡沉积研究的发展现况,对近些年蜡沉积机理研究的新进展--剪切剥离以及老化机理作了分析。介绍了冷板、冷指实验装置和环道实验装置,对国内外学者进行的蜡沉积实验情况作了概述。介绍了国内外单相原油与油水两相蜡沉积动力学模型的研究现状,在单相模型基础上对Couto油水两相模型和Bruno改进模型进行了描述。今后的研究应以蜡沉积机理与预测模型为重点,分析油水两相流蜡沉积的影响因素,这对于缓解输油管道蜡沉积问题,增强管道输送能力具有现实意义。     

Investigation of wax deposit ‘sloughing’ from paraffinic mixtures in pipe flow

Deposit ‘sloughing’ from ‘waxy’ crude oils has been described in the literature as a possible mechanism, leading to partial or complete dislodging of the deposit from the pipe wall due to changes in flow parameters. A bench‐scale flow loop apparatus was used to investigate ‘sloughing’ with prepared single‐phase ‘waxy’ mixtures of a multicomponent paraffinic wax dissolved in a multicomponent solvent. Experiments were performed to study the changes in the deposit‐layer thickness due to step increments in the ‘waxy’ mixture flow rate, the mixture temperature, and the coolant temperature. It was observed that the deposit‐layer thickness decreased with an increase in each of the three parameters; however, a complete or sudden dislodging of the deposit‐layer did not occur in any of the experiments. A steady‐state heat‐transfer model was used to predict the variation in the deposit mass or thickness due to changes in the selected parameters. In each case, the step‐wise decrease in the deposit thickness, as observed experimentally, was predicted to be caused by changes in the thermal resistance and/or thermal driving force.     

含蜡原油管道结蜡厚度的计算

在含蜡原油管道的日常运行管理中,结蜡厚度是个重要参数。经常根据这个参数评价管道内部的结蜡情况．借此进行工况分析或者调整管道的运行参数。为此．建立了含蜡原油管道结蜡厚度的计算模型,并给出了相应的求解方法。求解方法快捷准确．且有较好的扩展性,结果满足工程要求。     

Characterization of the wax precipitation in Mexican crude oils

This paper reports the rheological and thermodynamic characterization of the wax formation phenomenon in three Mexican crude oils where the effect of waxes and asphaltenes content on wax precipitation and rheological behavior of crude oils is evaluated and discussed. Wax appearance temperature is measured by using differential scanning calorimetry, rheometry and densitometry. The wax precipitation curves were obtained by fourier transform infrared spectroscopy. Pour point temperatures were evaluated according to the ASTM-D97 method, whereas gelation temperatures were determined by rheological experiments made with a controlled-stress rheometer. Waxes of the crude oils were separated and characterized by gas chromatography/mass spectrometry and differential scanning calorimetry. The methods used in this work for the wax appearance temperature determination showed to be sensitive to the crude oil composition. Results showed that the presence of asphaltenes impacts significantly the liquid–solid equilibrium and rheological behavior of the crude oils studied whereas the wax melting temperature was a key factor to evaluate the propensity of crude oils to present wax precipitation problems.     

氧化蜡过氧化价快速测定方法的研究

建立了一种氧化蜡过氧化价的快速测定方法，考察了溶剂、测定温度、反应时间对测定结果的影响。该方法重复性好，相对标准偏差分别为0.2%（氧化石蜡）和0.3%（氧化微晶蜡），可用于测定不同氧化程度的氧化石蜡、氧化微晶蜡的过氧化价，而且该方法具有快速、简便的优点。     

Effect of wax inhibitors on pour point and rheological properties of Iranian waxy crude oil

A variety of techniques have been employed in order to reduce problems caused by the crystallization of paraffin during the production and/or transportation of waxy crude oil. Flow improvers are used extensively to increase the mobility of crude oil. In this study, the influence of the ethylene-vinyl acetate copolymer (EVA), as flow improver, with different ranges of molecular weight on the viscosity and pour point of five Iranian waxy crude oils was evaluated. Five types of Iranian waxy crude oil were selected based on their similar wax (> 10%) but different asphaltene contents. Also, the effect of asphaltene content on the performance of this flow improver was studied. The rheological behavior of these crude oils, with middle range API gravity, in the absence/presence of flow improver was studied. The rheological data cover the temperature range of 5 to 40 °C. The results indicated that the performance of flow improver was dependent on the molecular weight and the asphaltene content. For crude oil with low asphaltene, higher molecular weight flow improvers are the best additive and lower molecular weight flow improvers showed good efficiency for crude oil with high asphaltene content. Addition of small quantities of asphaltene solvents such as xylene (1 wt.%), alone or in combination with flow improver, can improve viscosity of crude oil with high asphaltene content.     

聚丙烯酸十八酯降凝剂对合成蜡油结蜡特性影响的研究

采用自主研发的Couette结蜡装置研究了聚丙烯酸十八酯（POA）降凝剂对合成蜡油体系结蜡特性的影响。通过对结蜡层表面样（远离结蜡筒）和底部样（靠近结蜡筒）的宏观观察、DSC放热、气相色谱及蜡晶微观结构的分析发现：POA的加入降低了蜡油体系的结蜡速率,加快了蜡油体系的老化速率,且在一定浓度范围内（50～200 μg·g^-1）导致了径向不均质蜡沉积结构的形成,从结蜡层表面到底部含蜡量逐渐升高,但在较高加剂浓度（400 μg·g^-1）时径向不均质蜡沉积结构消失;POA的加入使得结蜡层表面样和底部样的临界碳数（CCN）都由C₂₄升高到C₂₅,但结蜡层底部样与表面样相比低碳数正构烷烃（≤ C₂₅）有所减少,高碳数正构烷烃（≥ C₂₆）有所增加;随着油样中POA浓度的增大,结蜡层表面样与底部样的蜡晶形貌由针状蜡晶逐渐转变为片状蜡晶,且蜡晶尺寸逐渐变大,结构更为致密。