管内含蜡原油降温过程的放热问题

利用两种管段和两种原油，进行了降温过程自然对流放热参数的测试和研究。采用滞流点确定降温第二阶段中凝油边界的移动，区分管内的对流区与导热区。由实验数据回归得到适用于含蜡原油降温过程的自然对流放热准则方程工式。用该方程式计算的自然对流放热系数值比按无限空间自然对流准则方程计算值小２０％～５０％。     

降温速率对胶凝含蜡原油流变性的影响

含蜡原油的流变性质具有对所经热历史和剪切历史的依赖性,降温速率是重要的热历史条件之一.对大庆含蜡原油进行不同降温速率条件下的流变实验,并对测得的胶凝温度、线性黏弹性参数和屈服应力等进行分析,总结出了降温速率对原油流变性的影响规律.     

降凝剂在海上含蜡原油管道中的应用

降凝剂在海上和陆上含蜡原油输油管道上的应用结果表明,降凝剂可降低含蜡原油凝点,改善含蜡原油低温流动性能,延长停输时间,减小停输再启动压力等,特别适用于海洋和沙漠中不宜建中间加热站的含蜡原油管道.对降凝剂的作用机理及其在海底管道的应用特点进行了介绍和论述.     

含蜡原油含蜡量与凝点关系的实验研究

实验主要是通过测定不同含蜡量的模拟油与现场提供的高凝原油的凝点,经过实验数据分析,拟合出含蜡量与凝点的关系曲线,并对此进行讨论,得出一个相对符合实际的结果,进而演绎原油含蜡量与凝点的关系。在现场中,可以通过测定原油的凝点来估测其含蜡量。     

降凝剂在海上含蜡原油管道中的应用

降凝剂在海上和陆上含蜡原油输油管道上的应用结果表明,降凝剂可降低含蜡原油凝点,改善含蜡原油低温流动性能,延长停输时间,减小停输再启动压力等,特别适用于海洋和沙漠中不宜建中问加热站的含蜡原油管道。对降凝剂的作用机理及其在海底管道的应用特点进行了介绍和论述。     

含蜡原油管道的设计计算程序

用一个计算机程序能解决输送牛顿体、假塑性体和屈服假塑性体原油管道的设计计算。     

热处理作用对含蜡原油流变性的影响

热处理技术是改善含蜡原油低温流动性的一种主要方法,以BH油田含蜡原油为例,通过一系列热处理试验对含蜡原油进行了流变性能研究,对实验数据进行了理论分析,并结合现场应用情况验证了试验结论的正确性。分析结果表明：温度是影响热处理效果的主要因素,中温段（50～60℃）的热处理会对含蜡原油的凝点产生恶化效果;高温段（70～95℃）的热处理可以大幅降低含蜡原油的凝点。冷却速度对含蜡原油热处理效果的影响至关重要,当冷却速度较小（0．5～1．0℃／min）时,油样热处理效果较好;冷却速度太快（1．2～1．5％／min）,将使热处理效果变差。剪切速率对热处理效果有一定影响,通常在较低速率的剪切作用下,原油热处理效果较好,随着剪切速率的增加,原油热处理效果变差。热处理后油样的稳定性对热处理效果的影响也不可忽视。     

管输含蜡原油添加降凝剂应用进展

含蜡原油在管道输送过程中会面临原油流动性降低、管壁结蜡等问题,使得管输工艺的动力费用增加、清管周期缩短,严重时会造成管道堵塞风险.向含蜡原油中添加一定剂量的降凝剂,可适当改善原油流动性,减小管道沿程摩阻损失,有助于降低管道运行风险、减小投资.针对管输原油工程添加降凝剂的应用及研究现状,简述了含蜡原油降凝剂的主要类型及作...     

The Thixotropy of Daqing Waxy Crude

The thixotropic behaviors of Daqing waxy crude were studied experimentally with the help of the advanced strain controlled rheometer (ARES-G2). The experimental results indicated the decrease in viscosity can be divided into two continuous steps, and the recovery of viscosity consists of three continuous processes. Then a new method was used to model the thixotropic behavior combined with the experimental data, and the new method was based on a potential function that can characterize the recovery capability of the inner structure, it is reasonable for to describe the thixotropic behavior of Daqing waxy crude properly.     

Viscosity Prediction of Non-Newtonian Waxy Crude Heated at Various Temperatures

Viscosities are important parameters for design and operation of crude pipelines. The heating temperature is the major factor affecting viscosities of waxy crude below the wax appearance temperature. Below the abnormal point, waxy crude exhibits non-Newtonian flow behavior with the viscosity dependent on the shear rate. Both of these make determination of the non-Newtonian viscosities of waxy crude a very time-consuming job. On the basis of the model for predicting non-Newtonian viscosity of waxy crudes as a function of temperature and precipitated wax, an approach to predict non-Newtonian viscosity of waxy crude heated to various temperatures has been developed only based on a few measurements. The accuracy of prediction by this approach has been verified by 468 viscosity data from the Daqing crude heated at various temperatures. The totally average relative deviation between the measured and predicted viscosity is 9.42%.     

Rheology of Doped Nigerian Niger-Delta Waxy Crude Oil

Abstract

Precipitation and deposition of wax, which usually results from temperature lowering, has detrimental effects on petroleum industry operations. To appreciate and understand the physicochemical mechanics of wax precipitation, rheological experiments were carried out on three doped and undoped Nigerian waxy crude oils. The characteristic shear stress straining rate shows an initial constant shear stress below 50 sec^?1 shear rate, followed by a gradual increase above 50 sec^?1 which is indicative of energy consumption in the partial break-up of wax matrix bonds. Doping greatly ameliorates the rheological properties and pour points of the crude oils. The Bingham plastic model excellently fit the experimental data, with a correlation coefficient ≥ 0.97721.     

含蜡原油相态转换边界值的计算

对含蜡原油相态转换边界值的计算进行描述，同时用实例进行数值分析，近年来，为提高原油产量，对油田开发不断地进行研究，同时也发展了许多新方法，在油层不断开采的情况下，由于复杂的渗流变化，伴随产生了油气相态转变和油气中各项密度和粘度的变化，因此，研究油层中油层相态转变，保持高压气体和富气来驱动原油开采是非常重要的。     

加剂模拟高蜡原油热性能的研究

用自由基溶液聚合法合成了丙烯酸十八酯/马来酸酐/苯乙烯共聚物,用正十六胺胺解共聚物中的酸酐基团,得到共聚物的不完全长链酰胺化产物,即为原油降凝剂PMB.以4种不同熔点的切片石蜡混合物在0号柴油中的溶液为模拟含蜡原油,以2℃/min的速率降温至约-50℃后升温测试,得到空白和加剂油的DSC曲线.含蜡25%的空白油,蜡晶型转变和蜡晶熔化溶解峰合并形成低宽峰,相变能29.28 J/g,加剂(200μg/g)油的两峰分离,后一峰很尖,出峰温度上移,熔程变长,相变能148.5 J/g,表明PMB参与共晶,且与蜡有良好的匹配性.含蜡30%的空白油的两峰明显分离.加剂量增大时(200～600μg/g),起始峰温移向低温方向,放热量(相变能)有所减小,原油降凝幅度增大,对于含蜡25%的模拟含蜡原油(凝点35℃),凝点降低幅度由6.5℃增至17.5℃,与加剂温度20℃时相比,加剂温度为50℃时的平均降凝幅度平均增加2.5℃.     

前南高蜡原油降凝剂的研究

文章选择了几种不同的单体进行聚合反应,得到了两种三元聚合物,并分别和EVA进行复配。依次考察了两种复配型降凝剂在不同加剂量和不同温度下对前南原油的降凝效果。实验结果表明:在加剂温度为70℃时,AMS-EVA复配降凝剂的最佳加剂量为0.03%,可使前南原油凝点降低9℃;AVS-EVA复配降凝剂的最佳加剂量为0.1%,可使前南原油凝点降低10℃。这两种复配型降凝剂均可以降低前南原油的黏度,改善其低温流变性。     

W/O型含蜡原油乳状液胶凝体系的屈服特性

在恒定剪切应力和剪切应力线性增加2种加载模式下,研究了油包水（W/O）型含蜡原油乳状液胶凝体系在凝点温度附近的屈服行为。以原油乳状液胶凝体系的屈服应变、屈服剪切速率为特征量,分析了剪切应力加载条件、加载量和胶凝体系含水率对含蜡原油乳状液胶凝体系屈服特性的影响规律。引用屈服应变比例系数的概念,分析了不同恒温静置时间后含蜡原油乳状液胶凝体系结构恢复程度及其影响因素。研究发现：屈服应变可作为W/O型含蜡原油乳状液胶凝体系屈服的判据;增大原油乳状液胶凝体系含水体积分数,屈服应变增大,屈服剪切速率减小,体系恢复度增加。增大剪切应力加载量或剪切应力增加速率,原油乳状液胶凝体系屈服剪切速率增大,该体系的结构恢复程度变差。     

Experimental Research on the Wax Crystal Particle Size Distribution of Waxy Crude Oil

The total settled mass of waxy crude oil has a close relationship with the particle size distribution of wax crystals. Wax crystal images of four kinds of crude oils were obtained with OPTIPHOT2-POL polarizing microscope. The wax particle size distribution was confirmed by image processing and data analysis. The results strongly suggest that wax particle size correspond to gamma distribution. Moreover, the range of wax particle size distribution expands with the increasing of temperature.     

The Formation of Waxy Crude Oil-in-water Emulsions for the Reduction of Pour Point and Viscosity

Waxy crude oil is characterized by high pour point and poor flow properties, which bring great difficulty to the oil exploitation and transportation. In this study, the fluidity of waxy crude oil with the pour point of 47°C was highly improved by emulsification with synthetic formation water used as aqueous phase. It was found that the combination of CAO-35 and sodium oleate was an effective emulsifier mixture to form stable waxy crude oil-in-water emulsion and when the mass ratio of oil to water was 7:3, the optimum composition of emulsifying additives with respect to the total mass of the emulsion was obtained as follows: emulsifier mixture (the mass ratio of CAO-35 to sodium oleate was 8:2) 0.4% (w/w), sodium triphosphate 0.028% (w/w), NaOH 0.05% (w/w), and polyacrylamide 0.15% (w/w). Diverse factors affecting the pour point of the formed emulsion were also studied. It was found that the pour point of emulsion increased as oil content increased and the optimum mixing speed and cooling rate were 600 rpm and 0.5°C/min, respectively. Under the optimum emulsifying conditions, when mixing speeds were 250 and 600 rpm, respectively, by forming O/W emulsions with the oil content of 70%, the pour point reductions were 20 and 25°C, respectively, and the corresponding viscosity reductions were 89.79% and 97.46% (40°C), respectively. Thus the pour point and viscosity of waxy crude oil are obviously reduced by forming oil-in-water emulsion, which is highly promising for the exploitation and transportation of waxy crude oil.