TLC-FID Calibration and Accurate Weight Determination of SARA Fractions in Heavy Crude Oil

Abstract

The authors specifically aimed to separate and characterize clean saturates, aromatics, resins, and asphaltenes (SARA) fractions and develop standards for accurate quantification purposes. A standard method ASTM D4124-86 was employed for the SARA separation of an Athabasca crude oil. These four recovered fractions were analyzed by using an Iatroscan thin-layer chromatograph with flame ionization detection (TLC-FID). The Iatroscan response to the complete burnoff of known sample weights of each fraction deposited on chromarods via known volumes of standard solutions was determined and area count versus sample weight calibration graphs subsequently obtained. From the established weight versus peak area calibration curves for each pure separated SARA fraction their accurate quantitative percentage in an Athabasca heavy crude oil was determined.     

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。     

Hydrotreating of Furrial Crude Oil Using NiMoS Supported on Alumina: Study of the Asphaltene and Their Fractions in Cyclohexane

Abstract

The Furrial crude oil originated in northern Monagas State. This shows problems such as the colloidal instability of the asphaltenes fraction present in them, causing its precipitation. This work is oriented to achieve an interpretation of the colloidal behavior of the asphaltenes through the study of the effect of the hydrotreating reactions (HDT) on the asphaltenes of the Furrial crude oil, using NiMoS/γ-Al₂O₃ as a catalyst. The results obtained after HDT reactions were analyzed to know the percentage of asphaltene and their fractions in cyclohexane, the measurement of flocculation thresholds and molecular weights by the VPO technique, and ¹³C NMR as well as the determination of the total sulfur content. Appreciable changes on the asphaltene of the Furrial crude oil and its fractions in cyclohexane after HDT, under conditions used, were observed. In general terms, the amount of asphaltene diminished and the percentage of distribution for insoluble fraction in cyclohexane (IFC) and for soluble fraction in cyclohexane (SFC) was affected causing an increase in the stability of the asphaltene. The asphaltene and IFC were observed to be a pronounced variation of the molecular weight average in number, in comparison with SFC. ¹³C NMR spectra indicate that the hydrotreated asphaltene shows structural change, and IFC presents a variation of the percentage of sulfur minor in comparison to SFC.     

Prediction of Asphaltene Precipitation in Live and Tank Crude Oil Using Gaussian Process Regression

The study of asphaltene precipitation properties has been motivated by their propensity to aggregate, flocculate, precipitate, and adsorb onto interfaces. The tendency of asphaltenes to precipitation has posed great challenges for the petroleum industry. Since the nature of asphaltene solubility is yet unknown and several unmodeled dynamics are hidden in the original systems, the existing models may fail in prediction the asphaltene precipitation in crude oil systems. The authors developed some Gaussian process regression models to predict asphaltene precipitation in crude oil systems based on different subsets of properties and components of crude oil. Using feature selection techniques they found some subsets of properties of crude oil that are more predictive of asphaltene precipitation. Then they developed prediction models based on selected feature sets. Results of this research indicate that the proposed predictive models can successfully predict and model asphaltene precipitation in tank and live crude oils with good accuracy.     

TLC/FID分析原油SARA组成方法研究

以渤海原油为研究对象,建立原油棒状薄层色谱／氢火焰离子化检测器（TLC／FID）族组分分析方法,对原油的四个族组分（饱和烃、芳烃、胶质、沥青,SARA）进行了分析。并对其影响因素展开次数、点样量、展开剂的干燥方式进行了优化,在优化所得条件下,方法的精密度RSD值为3．54％,方法重现性RSD值为3．23％。与文献报道方法相比,本文建立的方法,可将原油中的胶质和沥青两个组分分开,更能全面反应原油的族组成成分,具有分析速度快、有机溶剂用量少、操作简单等特点。最后将建立的方法应用到不同来源的原油中,结果令人满意。     

Evaluation of Trace Metals and Physical Properties of Nigerian Crude Oil Saturate Fraction

Analyses of trace elements and physical properties of the saturate fraction of Nigerian crude oil were done in order to establish the characteristics that may aid the developmental processes of the natural resources. Crude oil samples were collected from three different oil fields in Niger-Delta area of Nigeria. The saturate fractions were eluted by column chromatography using n-hexane. The saturate fractions were investigated for functional groups using Fourier transform infrared spectrometry (FT–IR); the elemental concentrations were determined using Atomic absorption spectrometry, while the physical properties (flash point, ash content, refractive index, and color) were determined using standard analytical methods. The results revealed that the infrared spectra of the saturate fraction of the Nigerian crude oil showed mainly the presence of C-H(CH₃) and C-H(CH₂) functional groups, indicating high purity of the samples. The concentrations of the analyzed elements (Mn, Cu, Co, Zn, Fe, V, Cr, and Ni) in the saturate fraction were generally low compared to other fractions of Nigerian crude oil. This study revealed that Co has the highest mean concentration of 1.81 ± 0.36 mg/L, while Mn has the lowest mean concentration of 0.04 ± 0.02 mg/L. The t test values for the comparison of the elemental concentrations of Nigerian crude oil /saturate fraction and crude oil asphaltene/saturate fraction showed significant difference (except Mn) with respect to Nigerian crude oil /saturate fraction. The cluster analysis for the elements showed two groups, which are fairly well correlated indicating similar source and similar chemical affinity. The cross-plot analysis of the Nigerian crude oil and its saturate using elemental concentrations as the variables showed a strong positive inter element correlation since (R² = 0.71), establishing a relationship between the Nigerian crude oil and the saturate fraction. The color of the saturate fraction ranged from off-white to colorless. The results of analysis provide useful information on its conversion mechanism and environmental implications of the development of the fossil fuel deposit.     

胜利原油活性组分对原油-甜菜碱溶液体系油-水界面张力的影响

采用传统的柱色谱四组分分离方法（SARA）将胜利孤岛原油分离得到沥青质、饱和分、芳香分和胶质,采用碱醇液法萃取原油得到酸性组分。测定了正构烷烃、煤油以及原油活性组分模拟油与2种不同疏水结构的甜菜碱溶液组成的体系的油 水界面张力。结果表明,在原油活性组分模拟油 甜菜碱溶液体系中,直链甜菜碱由于疏水基团较小,与原油活性组分尤其是酸性组分和胶质发生正协同效应的混合吸附,使油 水界面上表面活性剂分子的含量增加,界面膜的排布更紧密,导致油 水界面张力降低;支链甜菜碱由于具有较大尺寸的疏水基团,煤油中少量的活性物质即可将油 水界面张力降至超低(<10-3 mN/m),而原油活性组分的加入,则使界面上表面活性剂分子的排布被破坏,削弱了界面膜原有的紧密性,导致油 水界面张力大幅度升高。     

Prediction of the Kinematic Viscosity of Crude Oil Fractions

Abstract

A generalized equation based on modified Eyring's theory for predicting kinematic viscosity of petroleum fractions is proposed in this work. The equation uses two reference fluids including a pair of (C6 and C10), (C10 and C14), or (C14 and C20) for petroleum fractions of molecular weight higher than 70 and lower than 300.

Validity and accuracy of this equation have been confirmed by comparing the obtained results of this equation with experimental data. In contrast to other correlations that require so many specific parameters for oil viscosity prediction, this type of equation requires only molecular weight and true boiling point. The results obtained in this work are in agreement with experimental data with an average absolute deviation (AAD) of less than 5%.     

CO_2在原油中的扩散及引起的沥青质沉积

CO2在原油中扩散和溶解,使得原油体积膨胀和黏度降低的同时,原油组分也发生变化,可能引起沥青质等重有机质沉积,伤害储层,因此需全面评价CO2在原油中的扩散和影响因素以及可能引起的沥青质沉积程度。用压力降落法测定了压力和沥青质含量对CO2在原油中的扩散系数和溶解度的影响。结果表明,随着压力增加,CO2在原油中的扩散系数成线性增加,溶解度先增加后降低。随原油沥青质含量的增加,CO2扩散系数降低,溶解度增加。CO2扩散后的原油沥青质含量大幅降低,最高降幅达94.6%,表明CO2在扩散过程中引起了沥青质的沉积。     

The Effect of Solvent Nature and Dispersant Performance on Asphaltene Precipitation from Diluted Solutions of Instable Crude Oil

Abstract

The asphaltene precipitation experiments were studied on El Furrial crude oil from western Venezuela, which is known to exhibit serious instability problems. A Turbiscan backscattering apparatus was used to evaluate the precipitation of asphaltenes with different solvents. The transmittance variation with time was studied as the crude was diluted with heptane, pentane, and cyclohexane. Linear alkanes-containing systems exhibit a two-stage behavior, whereas only one is found when diluting with cyclohexane. Dispersing agents were tested by using the precipitate height as a criterion of effectiveness. Results are reported for ethoxylated nonylphenols and a commercial dispersant.     

稠油组分在水包油乳状液中作用机理的研究——Ⅰ．稠油组分分离及基本性质研究

本文主要研究了稠油的组分分离及其基本性质,为稠油组分在水包油乳状液中的作用机理研究提供基础数据.首次建立了将稠油分为酸性分、碱性分、两性分和中性分四组分的离子交换色谱分离技术.采用该分离技术对辽河杜-84稠油和胜利孤岛垦西稠油进行了组分分离,同时用极性分离法将稠油分为饱和分、芳香分、胶质和沥青质四组分.之后对这些纽分进行了元素、酸碱值、相对分子质量及红外光谱等组成结构测定.结果表明,杜-84稠油中酸性分、碱性分、两性分含量达36.92%;孤岛垦西稠油中酸性分、碱性分、两性分含量达20.65%.元素分析、酸碱值和红外光谱分析结果表明,分离效果较好,离子交换色谱分离法收率可达95%以上.极性四组分以沥青质相对分子质量最高(2000-3000),且辽河沥青质比孤岛沥青质要大许多,反映出辽河稠油的超稠油特性;相对分子质量大小顺序为沥青质＞胶质＞芳香分＞饱和分;官能团四组分中,碱性分相对分子质量最大(1150-1222),其它由大到小依次为两性分、酸性分、中性分.     

Dispersion Properties of NMR Relaxation for Crude Oil

Special requirements for design of tools used for wireline NMR logging and NMR logging while drilling and for interpretation model are demanded due to the dispersion properties of NMR relaxation for crude oil. NMR longitudinal relaxation time (T_1) and transverse relaxation time (T_2) of the dead oil samples with different viscosities were measured by NMR spectrometers with a Larmor frequency of 2 MHz and 23 MHz at five different temperatures respectively. The results showed that T_1 was obviously dependent on the Larmor frequency of NMR spectrometer. The degree of T_1 dispersion became stronger with the increasing crude oil viscosity, Larmor frequency and the viscosity/temperature ratio. T_2 was independent of NMR spectrometer measuring frequency. It is suggested that the resonance frequency should be selected lower than 2 MHz when measuring T_1 in logging while-drilling and that T_1 dispersion should be corrected when Larmor frequency is higher than 2 MHz.     

原油族组分的分离及检测方法

比较了SY/T5119—2008方法、原油族组分柱色谱分离常规方法和EPA3611方法等柱色谱法对原油族组分的分离效果;并在EPA3611方法的基础上,建立了一种新型原油族组分柱色谱分离方法(简称改良方法),改良方法以较少氧化铝为固定相,以正己烷、正己烷与二氯甲烷混合溶剂(体积比3∶1)、无水乙醇为洗脱液分别洗脱出原油中饱和烃、芳烃、胶质组分,达到较好分离原油族组分的目的。同时建立了TLC/FID评价原油族组分柱色谱分离效果的方法。用TLC/FID技术评价了4种柱色谱法分离原油族组分的效果。实验结果表明,较其他3种方法相比,改良方法的分离效果好、溶剂用量少、分析时间短、操作简便;同时,TLC/FID技术可一次性检测柱色谱分离的4种族组分,具有快速、微量等特点,可用于原油族组分柱色谱分离效果的监测。     

委内瑞拉原油中钒卟啉的分离和鉴定

 采用溶剂萃取、柱色谱分离工艺分离委内瑞拉380原油中的金属卟啉化合物,并采用紫外-可见吸收光谱和质谱方法,对金属卟啉化合物的结构进行鉴定。结果表明,当乙腈为溶剂时,可以有效地将金属卟啉从委内瑞拉380原油中萃取分离;硅胶为吸附剂时,可以实现不同类型的镍、钒卟啉的柱色谱清晰分割。委内瑞拉380原油钒卟啉化合物中ETIO(初卟啉)型钒卟啉占80.7%(质量分数),DPEP(脱氧叶红初卟啉)型钒卟啉占19.3%(质量分数),2种类型卟啉系列中含量最丰富的分别是C₂₈-ETIO和C₃1-DPEP。     

Separation and Characterization of Naphthenic Acids Contained in Penglai Crude Oil

Abstract

Naphthenic acids were separated from highly acidic Penglai crude oil by aqueous alkaline solution and analyzed by infrared spectrum (IR) and mass spectrum (MS). According to our results, the solution was composed of ethanolamine, alcohol, and water, the ratio being 0.1:7.9:10. When the solution and crude oil (ratio 0.4:1) were stirred at the speed of 300–400 r/min at 50°C for at least 10 min, more than 70% of the naphthenic acids in the crude oil could be removed. IR and MS results confirmed the presence of diversified naphthenic acids in Penglai crude oil and provided relative content information.     

南堡凹陷原油芳烃地球化学特征

通过对南堡凹陷原油GC-MS分析,研究了原油芳烃组成特征,探讨了原油成因。结果表明,南堡凹陷原油主要形成于弱氧化的淡水湖相沉积,为成熟原油。通过芳烃化合物组成及萘系列、联苯系列化合物内部相对丰度关系表明．沙河街组原油与东营组、馆陶组原油在源岩有机质输入方面有一定的差异,其中东营组和馆陶组原油有机质输入中高等植物有较大贡献,可能来源于南堡凹陷东三段或沙一段烃源岩,而沙河街组原油来源于沙三段烃源岩。     

原油乳状液稳定性研究 Ⅱ.原油成分对原油乳状液稳定性的影响

原血成分的表面活性物质及其细微固体颗粒,在油水界面上相互作用是原油乳状液其有稳定性的主要原因。本文采用简单的方法将原油中众多的物质分成两大类,并根椐它们单独时或混合后对癸烷/水乳状液稳定性作用的特征,将其分别称为原油乳化剂和原油破乳剂。试验表明,原油乳状液稳定性的高低主要取决于所含的这两大类物质的多少和相对比例,其相对重要性可由界面张力定性地反映出来;并且由原油/水界面张力的大小可以定性地评估原油乳状液的稳定性。     

Prediction of wax content in crude oil and petroleum fraction by proton NMR

In this study, we develop a simple method for estimation of wax content in crude oil and their fractions. The traditional way of wax estimation follows low-temperature chemical extraction based gravimetric methods; those are tedious, time-consuming, need a lot of chemicals and solvents and may produce an erroneous result if not done properly. This study proposes an alternative method i.e. ¹H NMR based correlation study to Englar Holde’s wax determination method. In this study, the NMR derived structural parameters of petroleum fractions are used to estimate the wax content of petroleum fractions. A Model equation is developed based on Fourier equation and validated with different Indian origin samples with a proper fitting and high predictability.     

Structural Characterization of Asphaltenes and Ethyl Acetate Insoluble Fractions of Petroleum Vacuum Residues

Asphaltenes and insoluble fractions of vacuum residues (VRs) of two Indian crude oils (viz. Heera and Jodhpur) of different specific gravity were obtained by precipitation of VRs in n-hexane, n-heptane, and ethyl acetate, and also by subsequent reprecipitation of n-heptane and ethyl acetate soluble fractions by n-pentane. The effect of various solvents on average molecular structure of asphaltenes and insolubles was studied using nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FTIR), and size exclusion chromatography (SEC). The asphaltenes and insolubles of Jodhpur VR have higher amounts of high molecular weight species with a high concentration of condensed and substituted aromatic rings, branched and/or short alkyl side chains, oxygen and nitrogen functionalities, compared to that of Heera VR. Ethyl acetate insolubles comprise a higher number of substituted aromatic structures, branched aliphatic structures, complex average unit structures, nitrogen and oxygen functionalities, and high molecular weight (MW) species as compared to hexane and heptane asphaltenes. Heptane insolubles consist of more naphthenic rings condensed with aromatic rings than C6A and EAI.     

混炼原油的评定与研究

将大庆原油与俄罗斯原油按不同比例混合，并分析实沸点切割的宽馏分性质，结果表明：随着进口油比例的增加，混炼原油的粘度和凝点都随之降低，有利生产低凝的煤油，柴油。混合比为50：50时轻质油收率最大，60：40时总拔出率最高。