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.     

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.     

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%.     

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。     

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.     

An Experimental Study on Wax Deposition of Water in Waxy Crude Oil Emulsions

Abstract

The key factors affecting wax deposition of water-in-oil emulsion were studied experimentally using a cold finger device. Wax deposition characteristics of emulsions were obtained. The results showed that the wax deposition profile of emulsions as a function of temperature parameters was similar to that of single oil. However, the effect of the extent of water cut on wax deposition was obviously different at different temperatures. Furthermore, the relative mass of deposit was proposed and found independent of water cut, from which wax deposition rate at different water cuts could be predicted and the predicted values were in good agreement with experimental data.     

Prediction of Viscosity Variation for Waxy Crude Oils Beneficiated by Pour Point Depressants During Pipelining

Pour-point-depressant (PPD) beneficiation is an emerging technology for facilitating pipelining of waxy crude oils. However, it was found both in lab studies and field tests that the viscosities of PPD-beneficiated waxy crude oils may increase as a result of pump shear or pipe flow shear during pipelining, called the shear effect. Current method for understanding this viscosity variation is to measure the viscosities by experimental simulation, which is quite time- and effort-consuming for long-distance pipelines. A new method for predicting the viscosity variation during pipelining is presented in this article based on a mathematical model for predicting viscosity of PPD-beneficiated waxy crude oils at certain temperature after shear and a model for predicting non-Newtonian viscosity of waxy crude oils as a function of temperature and precipitated wax. As verification, viscosity variations of five PPD-beneficiated waxy crude oils during pipelining are predicted by using the presented method and compared with the measured data from experimental simulations. The predicted viscosities are in good agreement with the measured data, with an average absolute deviation of 14.1% for all 52 data points. Comparisons between the measured or predicted viscosities during pipelining and viscosities obtained from the fast cooling experiment of PPD effectiveness evaluation demonstrate that the evaluation of PPD effectiveness for practical application should take the shear effect into consideration. The presented method provides a new way to evaluate the PPD's effectiveness in pipelining application quickly and effectively.     

用于高含蜡原油的双聚合物降凝剂的研制

通过在有机溶剂中进行的引发聚合 ,由摩尔比 2∶3∶3的马来酸酐、丙烯酸十八酯、醋酸乙烯酯合成了共聚物降凝剂A ,由摩尔比 1∶2∶3的苯乙烯、马来酸酐、丙烯酸十八酯合成了共聚物降凝剂B。A和B均为质量分数 30 %的溶液。简介了合成方法。A +B组合实验和组合物加量实验结果表明 ,对于密度 86 8.9kg m3、含蜡量 2 6 .6 %的辽河曙光原油 ,质量比 3∶1的A +B的降凝降粘效果最好 ,加入量为 0 .5 %时原油凝点由 2 9℃降至 2 1℃ ,80℃、15 0s- 1下的粘度由 2 0 0 0mPa·s降至 95 0mPa·s,降粘率达 5 2 .5 % ;对于密度 886 .7kg m3、含蜡量 18.9%的吉林新民渣油(原油减压蒸馏釜底残液 ) ,质量比 1∶2的A +B的降凝降粘效果最好 ,加入量为 0 .4 %时渣油凝点由 13℃降至 1.0℃ ,80℃、15 0s- 1 下的粘度由 95 0mPa·s降至 2 6 0mPa·s,降粘率达 72 .6 %。降凝剂A +B加量增大时 ,原油和渣油的凝点、粘度均降低。表 3参 8。