Effect of Crude Oil Composition and Blending on Flowing Properties

Abstract

The effect of crude oil n-paraffin molecular weight distribution on wax crystallization risk was studied. Sixteen highly paraffinic crude oils from Eastern Venezuela were characterized, in terms of hydrocarbon family distribution, by High Temperature Simulate Distillation (HTSD), Gel Permeation Chromatography (GPC), and wax content. n-Paraffin chain length was correlated with crude oil cloud point and pour point. It was demonstrated that high molecular weight linear paraffins are responsible for crude oil wax precipitation. A quantitative correlation between molecular weight distribution and crude oil flowing properties was also obtained. It was found that the wider the molecular weight distribution, the lower is the wax crystallization risk. Blends of different paraffinic crude oils were prepared and their flowing properties were evaluated in comparison with the original crudes. Cloud points below the mean value were obtained. In some cases, a synergistic effect was observed (cloud points below the minimum of the two crude oils). Blends of some of these crudes with condensates afforded improvements on crude oil flow and a reduction of wax crystallization tendency (cloud point). This phenomenon can be attributed to a combination of two factors: I. increases in C24-n-paraffins, and II. a wider molecular weight distribution.     

Distillation Yields from Blending Cabinda Crude Oil and Oman Crude Oil

Abstract

The blending optimization of Cabinda and Oman crude oil was investigated to provide a consistent and optimal feedstock to refinery operations. The distillation yields < 520°C and products' distribution were studied by equilibrium-fresh vaporization (EFV) method. The results revealed that the optimal blending ratio of Cabinda and Oman crude oil was 7:3, the distillation yield before 520°C was 73.90%, 3.87% higher than the theoretical distillation yield. Relationship of distillation yields, kinematic viscosities (50°C), and surface tension (25°C) showed that the change of kinematic viscosities and surface tension were contrasted with the change of distillation yield, and meanwhile, the diesel fraction output was comparatively increased during blending distillation.     

原油流动改性剂

英台油田原油高蜡、高胶质,井筒结蜡严重,地面集输困难,只能采取高温掺输,过高的掺输温度直接导致集输管网严重结垢。为解决上述问题,英台油田采取了加入原油流动改性剂的方法。通过现场试验,使用改性剂后,实现了流体由油包水型向水包油型的转变,可以使系统在较低的温度下运行。试验区块大部分油井实现了全年常温输送,节能降耗效果显著。     

原油性质对油井结蜡程度的影响

主要就原油的性质对结蜡程度的影响,以及采油井的结蜡规律进行了研究。通过实验得出结论如下:对于不同的油井,原油的含蜡量越高,在相同油井深度处结蜡蜡样的含蜡量也越高,油井结蜡越严重;对于同一口油井,随着油井深度的增加,结蜡蜡样的蜡含量、蜡样相对密度和凝点也相应增加;油井深部结蜡严重,越靠近井口结蜡越轻。     

地层原油组成差异对高压物性参数的影响

地层油高压物性参数主要受温度、压力等因素的影响,而地层油自身的组成也对其有着重要影响。对S48井、G942井和F154井的地层油进行了一系列的高压物性实验研究。结果表明：相同气油比,原油含蜡量越高,地层油泡点压力越高,体积系数越大;当压力高于泡点压力时,原油含蜡量越低,溶解气量越多,地层油体积系数和密度受压力的影响越显著;含蜡量越高,体积系数和密度受压力的影响越小。含蜡量高的地层油溶解天然气后的降黏效果明显好于含蜡量低的地层油。     

An Optimization Model for Shanbei Crude Oil Blending

The basic properties of the Shanbei crude oils and its mixed were studied first. Then, a hybrid coefficient function for the viscosity of the mixed oils was introduced. With these, an optimization model of the proportion for the crude oils blending was established and solved. An applicable proportion for six Shanbei crude oils’ blending was given. With the proportion, one mixed oil was prepared and distilled. Fouling and coking are discussed with the simulation in the distillation to assist the optimization. The experiment results showed that the model was valid for the oils blending.     

Crude Oil Blending Effects on Asphaltene Stability in Refinery Fouling

It has been known for some time that blending of incompatible crude oils may lead to asphaltene destabilization. The link between such asphaltene destabilization and their subsequent fouling of equipment in refinery operations was established in this study. Several refinery crude blends known to cause problems ranging from desalter upsets to fouling in pre-heat train were studied. Stability analysis of the crudes and their blends using a solvent titration method with a laser-based solids detection system showed that destabilization of the asphaltenes is caused, in the main, by blending of incompatible crudes. The stability data showed that the individual crudes had a high, medium, or low fouling potential. The blends of those that are incompatible however showed increased instability and may be the cause of the fouling problems encountered in the pre-heat train heat exchangers during their processing.     

Crude Oil Blending Effects on Asphaltene Stability in Refinery Fouling

Abstract

It has been known for some time that blending of incompatible crude oils may lead to asphaltene destabilization. The link between such asphaltene destabilization and their subsequent fouling of equipment in refinery operations was established in this study. Several refinery crude blends known to cause problems ranging from desalter upsets to fouling in pre-heat train were studied. Stability analysis of the crudes and their blends using a solvent titration method with a laser-based solids detection system showed that destabilization of the asphaltenes is caused, in the main, by blending of incompatible crudes. The stability data showed that the individual crudes had a high, medium, or low fouling potential. The blends of those that are incompatible however showed increased instability and may be the cause of the fouling problems encountered in the pre-heat train heat exchangers during their processing.     

Effect of Alkali on Daqing Crude Oil/Water Interfacial Properties

Alkaline-surfactant-polymer(ASP)flooding using sodium hydroxide as the alkali component to enhance oil recovery in Daqing Oilfield,northeast China has been successful,but there are new problems in the treatment of produced crude.The alkali added forms stable water-in-crude oil emulsion,hence de-emulsification process is necessary to separate oil and water.The problems in enhanced oil recovery with ASP flooding were investigated in laboratory by using fractions of Daqing crude oil.The oil was separated into aliphatics,aromatics,resin and asphaltene fractions.These fractions were then mixed with an additive-free jet fuel to form model oils.The interfacial properties,such as interfacial tension and interfacial pressure of the systems were also measured,which together with the molecular parameters of the fractions were all used to investigate the problems in the enhanced oil recovery. In our work,it was found that sodium hydroxide solution reacts with the acidic hydrogen in the fractions of crude oil and forms soap-like interfacially active components,which accumulate at the crude oil-water interface.     

两亲物官能团极性对沥青质缔结状态及草桥稠油流动性能的影响

笔者以十二烷基苯磺酸(DBSA)、十二胺(DDA)、月桂酸(LA)及草桥稠油为研究对象,通过实验测试体系离心稳定性、体系导电性及流动性,分析沥青质与分散介质间的溶剂化作用强度,沥青质自身的缔合程度,进而讨论烷基链长度相同情况下,官能团极性对沥青质稠环芳烃片层缔合状态及胶束溶剂化程度的影响。结果表明,针对草桥稠油,DBSA会增大沥青质缔合体的离心稳定性,提高体系电导率,增大稠油黏度;DDA会破坏沥青质缔合体的离心稳定性,降低体系电导率,降低稠油黏度。压缩沥青质缔合体结构,削弱沥青质溶剂化作用,可以降低稠油黏度。     

油相组成对无碱二元驱油体系界面性质的影响

通过测定原油与石油磺酸盐KPS-2/聚合物二元SP复合驱体系间的界面张力,研究了原油组分变化对界面特性的影响。结果表明,相对分子质量较大的有机酸对降低平衡界面张力有利,相对分子质量较小的有机酸对降低初始界面张力有利;沸程在180～210℃间的原油馏分与SP驱油体系间的界面张力达到了超低;原油放置过程中,组分氧化要比轻质组分挥发对界面张力影响大;较之石蜡基原油,KPS-2更适合与其疏水链结构相似的环烷基原油。     

水力空化对沙重原油性质的影响

基于水力空化过程能够产生局部的高温、高压、高射流、强大的剪切力等极端物理条件,提出利用水力空化装置改质处理沙特重质原油(沙重原油)的设想,考察了常温下水力空化压力和处理次数对沙重原油性质的影响;并通过理化性能分析、实沸点蒸馏实验和减压渣油延迟焦化反应考察了水力空化处理前后原油的性能。结果表明：当水力空化压力为4 MPa,处理1次时,沙重原油改质效果最佳：其20  ℃时密度、40  ℃时黏度、残炭、相对分子质量分别由0.8967 g/cm³、13.61 mm²/s、7.16%、467降低至0.8710 g/cm³、7.22 mm²/s、6.48%、443;经过空化处理的原油中减压渣油质量分数降低约1.0百分点;减压渣油延迟焦化的焦炭产率降低1.85百分点,液相和气相产品的收率分别增加1.52和0.33百分点。     

典型原油深拔蜡油及渣油性质研究——辽河原油深拔蜡油及渣油性质研究

对辽河原油进行了深度蒸馏试验,对深度蒸馏所得的深拔蜡油和深拔渣油进行了详细的研究。研究结果表明:辽河原油各窄馏分密度均较大,沸点>535℃以后的窄馏分氮含量较高,沸点>570℃以后的窄馏分镍含量较高。采用深拔VGO作催化裂化原料,深拔切割点不宜大于570℃。当蜡油的切割点提高到570℃时,蜡油收率可比常规蜡油增加8·02%(占原油)。深拔受到深拔渣油性质的限制,各不同深度渣油均属较难加工的渣油。大于500℃以后各不同深度渣油适合于生产沥青产品。     

Rheological Properties of Russian Crude Oil

Russia has 7.2 billion tons of difficult to produce, high-viscosity (over 30) crude oils. The reserves of these crudes are concentrated in 267 fields [1]. The Russian field located within the Polar circle — in the Gas Region of the Yamal-Nenets Autonomous District in Tyumen Oblast', is one of the largest. This field, opened in 1968, has total crude oil reserves of up to 1.5 billion tons. Its industrial exploitation has not yet begun.     

胜利原油各组分对界面膜扩张流变性的影响

 采取经典的四组分分离方法(SARA)将胜利原油分离得到饱和分、芳香分、胶质和沥青质,利用醇碱萃取法得到酸性组分。通过滴外形分析方法系统研究了上述5类原油组分及稀释原油的界面扩张流变性质,考察了振荡频率和各组分质量分数的影响。结果表明,各类活性组分及稀释原油表现出与表面活性剂类似的界面扩张行为,扩张模量均随振荡频率增大而增大,随质量分数的增加先增大后减小;相角随振荡频率增大而降低,随质量分数增大而增加。各组分模拟油及稀释原油形成的界面膜均表现出较强的弹性行为,且按其界面行为可以分为3组：稀释原油和饱和分、酸性组分和胶质、芳香分和沥青质。模量最大值对应的质量分数高低顺序为稀释原油和饱和分、酸性组分和胶质、芳香分和沥青质。沥青质扩张模量的最大值在 25 mN/m 左右,略高于稀释原油和其它活性组分。     

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.     

原油粘度的波动对输油工况的影响

通过分析输油管道进泵原油组分的变化，引起原油运动粘度产生偏离设计值的波动，该波动具有随机性，是无法预测的。原油粘度的波动会影响输油工况的稳定，降低离心泵和电机的效率，降低燃油锅炉的燃烧效率，影响降粘剂的最佳用量和原油的最佳加热温度。     

川中原油的性质与加工分析

川中原油随着时间的变化，其少数性质也在改变，由于川中原油产量不多，对其性质的研究和加工方法的讨论也不多，本文就根据目前的情况进行讨论     

聚合物驱残留物对原油破乳的影响

通过测定油田产出物的脱水率,考察聚合物驱残留物对原油破乳的影响,并对各种影响因素进行了分析。结果表明,随着产出物中聚合物浓度增加,破乳难度加大,产出物中含有疏水缔合聚合物AP-P4比含有MO4000破乳更困难。同时比较了聚醚型和双子结构破乳剂,双子结构破乳剂可将界面张力降至超低,有效地破坏界面膜,具有比普通聚醚型破乳剂更好的破乳效果。     

孤岛原油中石油羧酸分布及组成的分析

采用红外、色质联用等分析手段对孤岛原油中羧酸的分布、结构及组成进行了研究。结果表明,孤岛原油中石油羧酸平均相对分子质量在490左右,脂肪酸中C14-16成分占50％以上;原油中环烷酸的碳数在9～30之间,相对分子质量范围为156～450。