Study of resin fraction of Nigerian crude oil using spectroscopic/spectrometric analytical techniques

Organics and trace metals of the resin fraction of Nigerian crude oil were analysed in order to characterise the fossil fuel. The crude oil samples were deasphaltened by n-pentane, while maltene fraction was fractionated into its components (saturates, aromatics and resin) using column chromatography. The organic compounds and elemental concentrations of the resin fraction were investigated using Fourier Transform Infrared Spectroscopy and Inductively Coupled Plasma Optical Emission Spectrometry respectively. The infrared spectra showed characteristic bands containing polar functional groups expected confirming that the resin was purely eluted. The elemental concentrations were found to be high compared to other fractions and was confirmed by their T-test values. Zinc had the highest mean concentration of 32.13 ± 35.66 mg/kg, while Mn had the least (1.14 ± 0.17 mg/kg). Results indicated that processing of the crude oil resin may cause catalyst poisoning/fouling, corrosion of equipment/pipelines. Therefore, adequate consideration of these trace metals must be taken before processing.     

Spectroscopic Characterization of Asphaltene Fraction of Nigerian Bitumen

This research article offers data on the spectroscopic elucidation of the asphaltene fraction of Nigerian bitumen in order to establish its features that might aid the developmental processes of the fossil fuel. Bitumen was extracted from the oil sands obtained from six locations where there were oil sand out-crops in Southwestern Nigeria using toluene via Soxhlet extraction and then deasphalted using n-pentane. The organic components of the precipitated asphaltenes were investigated using Fourier transform infrared spectrometry, while the elemental contents were determined using Inductively coupled plasma atomic emission spectroscopy and carbon/nitrogen analyzer. The results revealed that the average content (29.15 wt%) of Nigerian bitumen asphaltenes was less than that of Athabasca (40.10 wt%) but slightly higher than that of Cold Lake bitumen (24.40 wt%). The IR spectra of the asphaltenes indicated the presence of various organics and heteroatoms corroborating that asphaltenes composed of high molecular weight polycyclic constituents comprising of nitrogen, sulfur, and oxygen heteroatoms. The results indicated that the values of Cr, Cu, Fe, Mn, Ni, S, V, and Zn were comparatively higher in the asphaltenes than the parent bitumen due to the presence of comparatively high levels of porphyrins in the asphaltenes than the bitumen, while the concentrations of all the elements were higher in the Nigerian bitumen asphaltene than Nigerian crude oil asphaltene (except S and C). Cross plot analysis result between the asphaltenes and bitumen using their elemental mean concentrations as variables indicates that significant and positive correlation (R² = 0.975) exists between them, indicating very strong interelement and geochemical relationships between them. The elements showed close clustering, indicating similar sources because the elements were known to associate with petroleum hydrocarbon formation. Also, apart from N, S, and C, other elements are transition metals with similar chemical affinity.     

The Structural Characterization of Saturate,Aromatic, Resin,and Asphaltene Fractions of Batiraman Crude Oil

Abstract

The structural characterization of fractions of Batiraman crude oil, which is the heavy crude oil from a field in the southeastern part of Turkey, was investigated. Batiraman crude oil and its saturate, aromatic, resin, and asphaltene (SARA) fractions were seperated. Treatment of crude oil with n-heptane provided the separation of asphaltene. Maltene was collected by evaporating the n-heptane from the filtrate. Then, maltene was separeted into saturates, aromatics, and resins by SARA technique. Maltene was separated into saturate, aromatic, and resin fractions using column chromatography. SARA fractions were quantified on a weight percent basis. Fractions of Batiraman crude oil were characterized by elemental analysis, proton nuclear magnetic resonance (¹H NMR) analysis, electrospray ionization mass spectrometry (ESI-MS), and Fourier transform infrared (FTIR) spectroscopy techniques.     

Chemical analysis of resin fraction of Nigerian bitumen for organic and trace metal compositions

Studies of organics and trace metals of the resin fraction of Nigerian bitumen were carried out with an opinion to establish the environmental consequences of the fossil fuel and as well as characterize them. Bitumen samples were extracted from oil sands via Soxhlet extraction procedure using toluene as the extracting solvent. The bitumen samples were deasphaltened to obtain maltene by dissolving the samples in n-pentane (1:40). Column chromatography was used to fractionate the maltene into its components (saturates, aromatics, and resin) using silica gel as adsorbent and dissimilar solvents of varying polarity (n-hexane for saturates, toluene for aromatics, and methanol for resins). The organic compounds of the resin fraction were examined using Fourier Transform Infrared Spectrophometry (FTIR) and the elemental concentrations were determined using Inductively Coupled Plasma Optical Emission Spectrophotometry (ICP-OES). The infrared spectra of all the resin samples presented distinctive bands including expected polar functional groups which confirmed that the resin was cleanly eluted from the bitumen samples. The concentrations of the analyzed trace metals in the resin fraction were found to be high compared to other fractions and this was confirmed by their T-test values. Fe had the highest average concentration of 34.81 ± 14.37 mg/kg and a range of 19.35–47.48 mg/kg, while Mn had the least mean concentration of 0.94 ± 0.71 mg/kg and a range of 0.35–1.88 mg/kg. The result of cross-plot analysis revealed that resin fraction has strong and positive inter elemental correlation with the NSO and asphaltene fraction of the same bitumen samples. The overall results indicated that processing of the bitumen and/or its resin may cause catalyst poisoning and fouling, corrosion of equipment and pipelines, and particulate emissions into the environment and therefore adequate demetalisation of the fossil fuel must be done before processing.     

胜利原油活性组分对其与烷基苯磺酸盐溶液组成的体系油-水界面张力的影响

 采用柱色谱四组分分离方法(SARA)对胜利原油进行分离,依次得到沥青质、饱和分、芳香分和胶质;采用碱醇液法萃取胜利原油得到其酸性组分,测定了各原油活性组分模拟油与烷基苯磺酸盐配制的系列标准溶液组成体系的油-水界面张力。结果表明,原油的酸性组分在低质量分数时通过改变油相的等效烷烃碳数（EACN）影响体系的油-水界面张力;高质量分数时则与表面活性剂混合吸附,使得体系油-水界面张力大幅度升高。胶质对其模拟油-表面活性剂标准溶液体系的油-水界面张力的影响与酸性组分的规律一致;沥青质的界面活性弱于酸性组分,混合吸附能力较弱,高质量分数时使体系油-水界面张力小幅度升高;饱和分和芳香分只影响油相的性质。     

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。     

基于ICP-MS/MS分析微量金属元素的原油产地溯源

建立电感耦合等离子体串联质谱(ICP-MS/MS)法测定原油中微量金属元素的分析方法,结合聚类分析(CA)建立判别模型,进行原油产地溯源研究。原油样品经微波消解处理后,采用ICP-MS/MS测定其中18种微量金属元素Mg、Al、Ti、V、Cr、Mn、Fe、Co、Ni、Cu、Zn、Rb、Sr、Mo、Ag、Cd、Ba、Pb的质量分数。在MS/MS模式下的碰撞反应池(CRC)中,应用O2或NH3/He为反应气可消除多原子离子对轻质量元素的干扰,采用国际标准物质燃油(NIST SRM 1634c)验证了分析方法准确可靠性,并利用多种微量金属元素质量分数的比值进行聚类分析。方法的检出限为0.43～59.2 ng/L,相对标准偏差(RSD)不大于4.82%;CA将18种原油聚为4大类,可实现原油产地的初步判别。通过微量金属元素的ICP-MS/MS分析,并结合CA能够对原油进行有效的产地溯源和判别。     

THE MIDDLE CAMBRIAN SUCCESSION IN THE CENTRAL BALTIC BASIN: GEOCHEMISTRY OF OILS AND SANDSTONE RESERVOIR CHARACTERISTICS

Some 36 oilfields, all producing from Middle Cambrian (Deimena Group) sandstones, are located in the central Baltic Basin in an area covering onshore Lithuania and Kaliningrad (Russia) and the adjacent offshore. This paper presents new data on the composition of crude oils from fields in this area and reviews the reservoir properties of the Deimena Group sandstones. Twenty‐one crude oil samples from fields in Lithuania and Kaliningrad were analysed by standard techniques including GC and GC‐MS. The oils had densities of 790.5 to 870.0 kg/m³, and had low asphaltene (<2.2%) and sulphur (<0.44%) contents. The gasoline fraction (b.p. >200°C) ranged from 12–34%. The saturated hydrocarbon content was 35.3 to 77.8%, and the ratio of saturate to aromatic hydrocarbons was 2.1–5.2, indicating long‐distance migration or high thermal maturities. GC analyses of saturate fractions indicated a composition dominated by n‐alkanes with a maximum at C₁₃–C₁₅ and reduced abundance in the C₂₀–C₃₅ range. The analysed crude oil samples are characterized by relatively low concentrations of steranes and triterpanes. Biomarker data indicated an algal origin for the precursor organic matter and a clastic‐dominated source rock. Sterane isomerization ratios imply that the oils are in general relatively mature. Exceptions are samples from the Juzno Olempijskoye and Deiminskoye fields, Kaliningrad, which were early mature. Oil from well Gondinga‐l (Lithuania) was lightly fractionally evaporated and has a relatively higher density, higher viscosity, higher asphaltene content and lower content of saturated fractions. Stable carbon isotope ratios of crude oils and saturated and aromatic fractions were analysed. Whole oils showed little carbon isotope variation, but there were significant differences in δ¹³C ratios for saturated and aromatic fractions. The geochemical data show differences in oil sourcing and indicate the possible existence of different kitchen areas in the Kaliningrad region. Vertical and lateral variations in Deimena Group reservoir properties are controlled by variations in quartz cementation. In fields in western Lithuania, sandstone porosity ranges from 0.7 to 20% and permeability from 20 mD to 300 mD; in fields onshore Kaliningrad, porosity is up to 34% and gas permeability up to 4.8 D. Wide variations in porosity and permeability occur at a field scale.     

The low temperature oxidation characteristics of SARA fractions in air flooding process

The Low Temperature Oxidation (LTO) characteristics of SARA fractions isolated from light crude oil were studied applying the static oxidation experiments. The results show that the LTO reaction of SARA fractions can occur when temperature is above 50°. Under reservoir conditions, the oxidation activities of the SARA fractions were resin > aromatics > saturate. The theoretical LTO reaction rate of crude oil calculated based on the SARA oxidation characteristics is in good agreement with the measured value. Therefore, it is an effective method to reveal the LTO mechanism of crude oil by studying the LTO mechanism of SARA fractions.     

大庆原油与碱作用机理研究

 采用四组分分离法将大庆原油分离为饱和分、芳香分、胶质和沥青质，并用醇碱萃取法提取原油中的酸Ⅰ组分和酸Ⅱ组分。分别考察了各组分模拟油与水及碱体系的界面张力、界面剪切黏度，以及模拟油与碱长时间反应所形成的乳状液稳定性。结果表明，大庆原油中能降低油-水界面张力的主要活性组分是与碱反应较快的酸；对模拟油与碱体系形成的W/O型乳状液起稳定作用的主要组分是其中与碱反应较慢的、支链较多的大分子酸及酯类。大庆原油饱和分中存在着与碱发生慢反应的酯类。原油、原油组分模拟油与 碱反应初期，易形成O/W型乳状液，反应后期乳状液由O/W型向W/O型转变。醇碱萃取法只能萃取出与碱发生快速反应的酸组分，而不能将与碱反应较慢的相对分子质量较大的酸或酯类萃取出来。     

SOURCE ROCK–DEPENDENT BIOMARKER PROPERTIES AND STABLE CARBON ISOTOPE COMPOSITION OF CRUDE OILS FROM WEST BAKR FIELDS,ONSHORE GULF OF SUEZ,EGYPT: A CASE STUDY

Four representative crude oil samples from three different pay zones (Ayun, Yusr and Bakr members) of Lower Miocene age from West Bakr Fields K, H and M, Gulf of Suez, Egypt were analyzed to evaluate the source rocks and their depositional environments. The saturate and aromatic fractions were subjected to a variety of organic geochemical analyses including Gas Chromatography (GC), Gas Chromatography-Mass Spectrometry (GC-MS), trace element analyses (V, Ni, Co, Cr, Fe, Mg, Mn, Ca and Zn) and stable carbon isotopic composition δ¹³C. The geochemical characteristics and biomarker properties of the studied crude oils show no obvious variations. All the studied crude oil samples are of naphthenic base and possess similar values of V/Ni ratio, suggest that the studied crude oils might be derived from the same source rocks. Moreover the ratios of Ts/Tm (< 1), Oleanane index (> 30%) and gammacerane index (> 20%) reflect a marine environment with minor terrestrial higher plants input from Tertiary source rocks deposited in high salinity waters with less reducing conditions. The enrichment of stable carbon isotopic composition δ¹³C to the saturate fraction ranges from (?29.1 to?29.35‰ PDB); and to the aromatic fraction ranges from (?28.35 to?28.60‰ PDB) is observed. The isotopic values together with the calculated canonical variable (CV) of the studied crude oil samples < 0.47, which further support that the crude oils of West Bakr Fields were generated from marine source environment. The achieved results obtained from the geochemical characteristics of the studied crude oils suggest marine environment with minor terrestrial higher plants input from source rocks of Tertiary age. These are likely to be interval within the Lower Miocene Rudeis shale and Eocene Thebes Formation carbonate rocks where the vertical and horizontal migration caused the oil to be entrapped within the sandstone of Lower Miocene age.     

Characterization of the isolated wetting crude oil components with infrared spectroscopy

To improve the understanding of wettability, especially the influence of different crude oil colloids, wetting experiments on quartz sand and kaolin were performed with an asphaltene rich oil. A two-step procedure was developed to investigate the wetting behavior. In the first step, those crude oil components were extracted, which preferentially wet solid surfaces. The extracted crude oil components were characterized in a second step. The composition of the fractions extracted with different solvents are different. The acetone fractions extracted from quartz sand are rich in compounds containing nitrogen, whereas the compounds containing sulphur predominate in the chloroform fraction extracted from quartz sand. IR spectroscopy of the extracted fractions shows that carbonyl compounds are abundant in the methanol/chloroform and acetone/chloroform fractions extracted from quartz sand. The chloroform fraction is poor in carbonyl group-containing compounds. In agreement with elemental analysis, a strong signal for C–N groups in the IR spectra is found for acetone/chloroform and methanol/chloroform fractions, extracted from the quartz sand system. On the other hand, a significant, strong IR-peak representing S=O containing components is observed in the acetone and acetone/chloroform fractions, extracted from quartz sand.     

Organic and Carbon Isotope Geochemistry of Crude Oils from Ashrafi Field,Southern Gulf of Suez Province,Egypt: Implications for the Processes of Hydrocarbon Generation and Maturation

Abstract

Four crude oil samples representing the Miocene formations of Belayim, Kareem, and Nukhul, and the Pre-Miocene Nubia Sandstone of Ashrafi Field, offshore southern Gulf of Suez, Egypt. These crude oil samples were analyzed using a variety of organic geochemical techniques including both C₇ and whole oil Gas Chromatography (GC), Gas Chromatography–Mass Spectrometry (GC–MS) in addition to stable carbon isotopes to the saturate and aromatic fractions. The organic geochemical results revealed that the Miocene and Pre-Miocene Nubia Sandstone oils generated from two different source rocks subjected to different maturation levels. The Miocene crude oil possesses geochemical properties rich in tricyclic terpanes and extended hopanes typical characteristics of oils generated from marine siliciclastic source rocks with angiosperm land plants input like Rudeis Formation as indicated from the oleanane index which exceeds 30% and low gammacerane index around 10%. Meanwhile the Pre-Miocene crude oil correlates with the marine carbonate sources of high salinity waters like Brown Limestone of Upper Cretaceous age as indicated from the oleanane index <10% and high gammacerane index >30%. The maturity parameters based on both ratios of 20S/(20S + 20R)-C₂₉ ααα cholestane and TAS/(MAS + TAS) were found to be around 0.5 for the Miocene crude oils, meanwhile both the ratios for the Pre-Miocene crude oil were >0.5. The concluded results further support the very high maturation level of the Pre-Miocene crude oil than the Miocene crude of Ashrafi Field which concordant with the reservoir stratigraphic depths.     

Characteristics of Gas Condensate

The characteristic features of Oso condensate and Delta condensate samples, including their gasoline potential, were determined using gas chromatographic integrator techniques. The analysis revealed that these condensate samples have recoverable gasoline of 41.65% wt and 49.82% wt., respectively. Both samples are from Cross-River and Delta regions of the Nigerian oil fields, respectively. Two other crude oil samples from the Delta region, Forcados and Bonny light, were also analyzed alongside the two-condensate samples for comparative study. These analytical results show that the two crude oil samples are less rich in light fractions than the condensate samples. The results of the analysis of the four oil samples lend support to the earlier report that Nigerian crude oils are mostly paraffinic in nature.     

APPLICATION OF BIOMARKERS AND STABLE CARBON ISOTOPES TO ASSESS THE DEPOSITIONAL ENVIRONMENT OF SOURCE ROCKS AND THE MATURATION OF CRUDE OILS, EAST ZEIT FIELD, SOUTHERN GULF OF SUEZ, EGYPT

Four crude oil samples were collected from the producing wells EZ A-11, EZ A-1, EZ A-14 and EZ A-7 of East Zeit Field, offshore southern Gulf of Suez, Egypt. These crude oil samples represent the producing Kareem, Rudeis, Nukhul and Nubia reservoirs respectively. The crude oils were subjected to a variety of organic geochemical analyses including Gas Chromatography (GC), Gas Chromatography-Mass Spectrometry (GC-MS). In addition to stable carbon isotopes were done for the saturate and aromatic fractions and trace elements analysis. The organic geochemical results suggest the presence of two different types of oils that were originated from two different source environments. The Lower Miocene Kareem, Rudeis and Nukhul oils have a V/Ni ratios of 2, Ts/Tm ratio less than 1, Oleanane index of more than 20% and a gammacerane index of around 10%. Such results suggest that the Miocene crude oils were generated from an angiosperm-rich, Tertiary source rocks with high terrestrial input. The Nubian crude oil has a V/Ni ratio equal 3.2, Ts/Tm ratio less than 1, Oleanane index less than 20% and high gammacerane index of more than 30% suggesting a marine saline-source depositional environment of Late Cretceous or younger rich in type-II kerogen with minor terrestrial influence. The maturation parameters of the Miocene and Nubian crude oils obtained from aromatic and fraction imply marginally mature to mature oils. The Nubian crude oil however, was generated at a relatively higher maturation level than that of the Miocene oils. Also, the maturation level of the Miocene oils is in accordance with their relative stratigraphic position with the Nukhul reservoired oil being the most mature.     

APPLICATION OF BIOMARKERS AND STABLE CARBON ISOTOPES TO ASSESS THE DEPOSITIONAL ENVIRONMENT OF SOURCE ROCKS AND THE MATURATION OF CRUDE OILS,EAST ZEIT FIELD,SOUTHERN GULF OF SUEZ,EGYPT

Four crude oil samples were collected from the producing wells EZ A-11, EZ A-1, EZ A-14 and EZ A-7 of East Zeit Field, offshore southern Gulf of Suez, Egypt. These crude oil samples represent the producing Kareem, Rudeis, Nukhul and Nubia reservoirs respectively. The crude oils were subjected to a variety of organic geochemical analyses including Gas Chromatography (GC), Gas Chromatography-Mass Spectrometry (GC-MS). In addition to stable carbon isotopes were done for the saturate and aromatic fractions and trace elements analysis. The organic geochemical results suggest the presence of two different types of oils that were originated from two different source environments. The Lower Miocene Kareem, Rudeis and Nukhul oils have a V/Ni ratios of 2, Ts/Tm ratio less than 1, Oleanane index of more than 20% and a gammacerane index of around 10%. Such results suggest that the Miocene crude oils were generated from an angiosperm-rich, Tertiary source rocks with high terrestrial input. The Nubian crude oil has a V/Ni ratio equal 3.2, Ts/Tm ratio less than 1, Oleanane index less than 20% and high gammacerane index of more than 30% suggesting a marine saline-source depositional environment of Late Cretceous or younger rich in type-II kerogen with minor terrestrial influence. The maturation parameters of the Miocene and Nubian crude oils obtained from aromatic and fraction imply marginally mature to mature oils. The Nubian crude oil however, was generated at a relatively higher maturation level than that of the Miocene oils. Also, the maturation level of the Miocene oils is in accordance with their relative stratigraphic position with the Nukhul reservoired oil being the most mature.     

Isolation of adamantane hydrocarbons from Cenomanian oil of the Russkoe oilfield

Adamantane hydrocarbons have been isolated from Cenomanian heavy naphthenic oil of the Russkoe field using the thiocarbamide adduction method. Steam distillation of the oil has given a fraction (boiling range 105–150°C) containing 0.36 wt % adamantane, from which a concentrate containing 18.2 wt % C₁₀–C₁₄ adamantane derivatives has been obtained. Adamantane and its derivatives in the crude oil, oil fractions, and concentrate have been identified, and adamantane has been quantified using the gas chromatography—mass spectrometry technique.     

郑王稠油四组分组成和油-水界面膜黏弹性的关系

采用化学分离和元素分析方法分析了郑王稠油的饱和分、芳香分、胶质、沥青质（SARS）的组成,测定了含有分离的四组分的油 水体系的界面扩张黏弹性,考察了振荡频率及组分浓度对油 水体系界面扩张黏弹性的影响。结果表明,含郑王稠油四组分的油 水体系的界面扩张模量均随振荡频率增大而增大,随组分质量分数的增大先增加后减小。含胶质、沥青质组分的油 水体系所形成的界面膜以弹性膜为主,抵抗形变能力更强;油 水体系中饱和分浓度增大,主要体现在其体相浓度增加,弹性模量变化不大,而黏性模量逐渐增大。含郑王稠油四组分的油 水体系的扩张相角均随振荡频率的增加逐渐减小,扩张相角由小到大的油 水体系为含沥青质的、含芳香分的、含胶质的、含饱和分的油 水体系。沥青质是四组分中对油 水体系界面膜黏弹性影响最大的组分。       

一种新的原油轻烃分类法——塔里木盆地原油分类及其地化特征

根据Mango提出原油中轻烃成因的假说--稳态催化成因,按“母体”(甲基己烷类)占C7化合物的百分数与两类“子体”(二甲基戊烷类+3-乙基戊烷;1,1和1,3-二甲基环戊烷类)丰度比的关系图,将塔里木盆地不同地区、层位的141个原油分成A、B两大类和四亚类。为了验证分类的有效性和研究影响分类的因素,对各类原油中微量元素、饱和烃的C₁₄⁺色谱、生标组成及其分布规律进行了综合研究。鉴于各类原油具明显的地化特征区别,且在地区、层位上有一定的规律性,证实根据Mango假说提出的新的原油轻烃分类方法在塔里木盆地是有效的,在高熟的油气区更有应用前景。研究成果支持Mango的观点,即影响轻烃分类的主要因素可能是受沉积环境控制的催化剂组成,此外干酪根类型等也可能有一定的影响。     

Sulfur compounds in the fuel range fractions from different crude oils

A gas chromatograph coupled with sulfur chemiluminscence detector (GC-SCD) has been used for the speciation of individual sulfur compounds in fractions of different crude oils. The crude oil fractions characterized were light naphtha (C5-90°C), heavy naphtha (90–140°C), kerosene (140–240°C), and gas oil (240–370°C) fractions obtained from true boiling point distillation process. Low boiling fractions (up to 140°C) were analyzed by existing ASTM D5623 (American Society for Testing and Materials, 2009a) method for sulfur compound speciation. As there is no standard method for the distribution of sulfur compounds in high boiling samples (up to 370°C), therefore, a methodology has been developed for the diesel range samples. The identification of individual sulfur compounds were carried out by using reference sulfur compounds. The results show that type of sulfur compounds depends upon the boiling range of the fraction and source of crude oil. The major changes in the sulfur compounds profiles of different fractions are discussed. The results of this study can be used to predict the suitability of crude oil for the production of Euro-IV and V gasoline and diesel fuels.