原油中C26－C28三芳甾烷相对含量计算方法及其应用

三芳甾烷（TAS）是规则甾烷芳构化产物,其中C₂₆-C₂₈三芳甾烷系列稳定分布于原油和烃源岩有机质中。在常规色谱-质谱分析得到的芳烃馏分（m/z231）质量色谱图上,由于C₂₆20R和C₂₇20STAS异构体共流出而不能确定3种不同碳数三芳甾烷的相对含量,无法建立类似于C₂₇-C₂₉规则甾烷的相对含量三角图,从而使三芳甾烷在油气地球化学中的应用受到限制。以塔里木盆地台盆区古生界代表性原油样品为例,建立了三芳甾烷相对含量三角图,并用北部湾盆地福山凹陷古近系原油进行了验证。结果表明:该区存在2种不同来源的原油,可以划分为2个不同的原油族群,而来自福山凹陷古近系的原油具有不同的C₂₆-C₂₈三芳甾烷组成特征,原油族群的划分也得到其他分子地球化学证据的支持。在高成熟的轻质油和凝析油中,规则甾烷系列由于浓度低而很难由常规的色谱-质谱分析技术进行检测和鉴定,三芳甾烷由于相对较高的热稳定性而稳定存在,因此可代替规则甾烷用于油-油对比和原油族群划分。      

GEOCHEMICAL COMPOSITION OF ORDOVICIAN OILS FROM THE TUOPUTAI REGION,NORTHERN TARIM BASIN,NW CHINA: SOURCE ROCK CORRELATION

Molecular and stable carbon isotope compositions of 46 Ordovician crude oil samples from wells in the Tuoputai region of the northern Tarim Basin were investigated using GC–MS, MRM GC–MS and IRMS to determine their genetic relationships and to identify possible source rocks. Thirty-three source rock samples from outcrops and cores were also investigated. The oil samples varied from light to heavy crudes and showed very narrow δ¹³C value ranges for the whole oil, saturated and aromatic fractions. The majority of the oils displayed very similar molecular compositions with relatively high concentrations of n-alkanes and isoprenoids and low concentrations of terpenoids and steroids. Comparison of the compositions of these crude oils strongly suggested their genetic affinity, while maturity parameters indicated maturity variations from the peak to the late oil generation stages. The samples also showed the characteristics of mixtures of biodegraded and fresh oil charges. Bitumen extracts from Cambrian and Ordovician source rocks were studied in detail. The oil compositions suggested a marine marl source deposited in anoxic, hypersaline conditions with significant bacterial and algal organic matter inputs. The distributions of C₂₆–C₂₈ triaromatic steroids, tricyclic terpanes and regular steranes appear to have been greatly influenced by thermal maturation, making them unreliable for correlating the oils and the source rocks. In contrast, dinosteranes and triaromatic dinosteroids seem not to have been affected by maturation and were more useful for correlation studies. They indicated that there was no or little genetic relationship between the Cambrian – Lower Ordovician source rocks and the oils, but in general suggested a possible Middle – Upper Ordovician source for the oil accumulations in the Tuoputai field. However, the occurrence of triaromatic dinosteroids in oil from well TP28XCX may also suggest a minor contribution from Cambrian – Lower Ordovician source rocks.     

OILS IN THE NW NIGER DELTA: AROMATIC HYDROCARBONS CONTENT AND INFRARED SPECTROSCOPIC CHARACTERISATION

The occurrence and distribution of aromatic hydrocarbons in oil samples from an oilfield in the NW Niger Delta was investigated, focussing on naphthalenes, phenanthrenes and mono- and triaromatic steroids. Tetramethylnaphthalene is the most abundant of the naphthalene homologues, while dimethylphenanthrene is the most abundant of the phenanthrene homologues. The relative concentration of the sum total of the phenanthrenes and their isomers was greater than that of the naphthalenes.
The distribution of naphthalenes and phenanthrenes was strongly controlled by thermal maturation and biodegradation of the oils. Various aromatic hydrocarbon- dependent geochemical parameters indicate that the oils are mature and were generated at similar levels of thermal maturation. Plots of these parameters showed that the distribution of homologues of both naphthalene and phenanthrene is sensitive to the biodegradation of the oils.
Infrared spectroscopy (IR) was used for geochemical characterisation of the NW Niger Delta oil samples in terms of both source type and thermal maturity. The characterisation was based on the peak intensities of the aliphatic and the carbonyl groups relative to the aromatics. The study showed that IR may be useful for the determination of thermal maturity, but is not a good tool for source characterisation.     

准噶尔盆地玛湖凹陷二叠系烃源岩三芳甾烷分布特征及油源对比

准噶尔盆地玛湖凹陷二叠系风城组、乌尔禾组和其他不同层系原油中普遍检测出三芳甾烷(TAS)和三芳甲藻甾烷系列。基于多口井的原油和14块代表性烃源岩样品的芳烃组分色谱-质谱资料,系统分析其TAS组成特征,并将其用于油源对比研究。结果表明：TAS分布特征可以有效区分准噶尔盆地玛湖凹陷二叠系风城组烃源岩和乌尔禾组烃源岩。风城组烃源岩中TAS具有C₂₆-20S含量低、C₂₇-20R含量高的分布特征,并且几乎不含有三芳甲藻甾烷;而乌尔禾组烃源岩中TAS具有相反的分布特征,即C₂₆-20S相对丰度较高,C₂₇-20R相对丰度较低,并且具有分布完整的三芳甲藻甾烷系列。玛湖凹陷不同层系原油TAS分布特征基本一致,主要表现为C₂₆-20S含量低,C₂₇-20R含量高,三芳甲藻甾烷含量低或者未检测出,与风城组烃源岩分布特征相似。应用C₂₆-20S/C₂₈-20S TAS与C₂₇-20R/C₂₈     

The Distribution of Triaromatic Steroids and Oil Group Classification of Ordovician Petroleum Systems in the Cratonic Region of the Tarim Basin,NW China

A practical method to estimate the abundance of each C₂₆-C₂₈ triaromatic steroid isomer was proposed and a triangular diagram can therefore be drawn to distinguish oil populations in the cratonic region of the Tarim Basin, NW China. The results indicate that oils discovered in this region can be divided into two petroleum systems. Oils derived from the Cambrian and Lower Ordovician source rocks show relatively high abundance of C₂₇ triaromatic steroids with the relative abundance of C₂₇ TAS being more than 25% of all TAS isomers. In contrast, the values are below 25% in oils and source rocks from the Middle-Upper Ordovician. The petroleum system definition is in agreement with previous studies using regular steranes, tricyclic terpanes, norcholestanes, and other molecular markers to distinguish oil groups. In addition, high thermal stability and greater resistance to biodegradation make triaromatic steroids more effective in distinguishing oil groups in the tectonic region of the Tarim Basin.     

松辽盆地西部图牧吉油砂地球化学特征

油砂是重要的非常规油气资源,对油砂的地球化学研究可以更好地指导油砂资源潜力评价。收集了13件松辽盆地西部图牧吉农场的油砂样品,并做了含油率、族组成以及色谱-质谱（GC-MS）分析。实验结果显示图牧吉油砂含油率较高,族组分中以非烃含量为最高。GC-MS分析饱和烃和芳香烃馏分中大部分化合物被降解,其中正构烷烃、藿烷和甾烷系列均受到不同程度降解,三环萜烷抗降解能力较强未受影响。芳烃化合物中萘和菲等化合物都已消失,三芳甾系列较完整。油砂中没有出现25-降藿烷系列,降解程度为6～8级,通过抗降解能力较强的化合物判断,原油基本来自同一油源。     

松辽盆地原油芳烃分布、组成特征与原油类型划分

通过色谱-质谱(GC-MS)分析,松辽盆地黑帝庙、萨尔图、葡萄花、高台子、扶余油层原油共检测到萘、菲、、联苯、芴、二苯呋喃、二苯并噻吩、三芳甾等11个系列164种芳烃化合物。其中,黑帝庙、萨尔图油层原油主要由三芳甾类化合物和菲系列化合物组成,葡萄花油层原油主要由菲系列和系列化合物组成,高台子、扶余油层原油主要由菲系列、系列和三芳甾类化合物所构成。菲系列、系列和三芳甾类化合物在纵向上的分布,均以葡萄花油层为拐点,由浅层黑帝庙油层至深层扶余油层,菲系列、系列呈现了由低变高的趋势,三芳甾类表现了由高变低的趋势。根据三芳甾含量、三芳甾类/菲系列、二甲基菲/三芳甾烷的组合关系,松辽盆地原油可划分为黑帝庙、萨尔图油层高三芳甾类原油,高台子、扶余油层低三芳甾类原油和葡萄花油层痕量三芳甾类原油。松辽盆地原油含有三芳甾类化合物和二苯并噻吩/菲很小,表明松辽盆地烃源岩主要形成于淡水-微咸水湖相的弱氧化环境。     

生物降解作用对芳烃生物标志物参数的影响研究

在大多数情况下,生物降解作用是造成原油变稠的最主要原因。目前,生物降解作用对饱和烃生物标志物和含氮化合物及参数的影响研究较多,而对芳烃生物标志物及参数的研究较少。选取渤海湾盆地渤中凹陷4个不同降解程度的原油样品,采用GC-MS分析测试,初步探讨了自然条件下,生物降解作用对原油中一些芳烃生物标志物参数(主要是成熟度指标)的影响。结果表明:运用甲基萘比(MNR)计算降解原油的成熟度时,结果比降解前的实际值小;运用甲基菲比(MPR)计算降解原油的成熟度时,结果比降解前的实际值大;而运用三芳甾烷/单芳甾烷(TAS/MAS)计算降解原油的成熟度时,基本不失真。      

塔河油田奥陶系原油芳烃地球化学特征

芳烃化合物是原油中重要的组分,在判识原油生源环境和成熟度方面应用广泛.塔河油田主体区奥陶系原油遭受过强烈的生物降解作用,常用的饱和烃生物标志化合物指标往往不能正确反映原油成熟度、运移等信息,芳烃化合物能有效抵制生物降解作用,可更好地反映这些地质信息.通过芳烃GC-MS分析,表明塔河奥陶系原油具有高萘、高菲、高硫芴、低氧芴、低联苯等特点,均来自同一油源,生烃母质属还原-强还原环境.烷基萘指数、二苯并噻吩和三芳甾烷等成熟度指标表明,塔河油田奥陶系原油成熟度由西向东、由北向南不断增高,反映出奥陶系油气主要来自沙雅隆起东南部的满加尔坳陷.      

UPGRADING OF SUGAR CANE BAGASSE BY THERMAL PROCESSES. 3. CHEMICAL CHARACTERIZATION OF THE PRODUCTS OBTAINED FROM THE CATALYTIC LIQUEFACTION OF BAGASSE WITH MONOETHANOLAMINE

The products obtained from liquefaction of sugar cane bagasse with monoethanolamine were characterized using a variety of methods: elemental analysis and UV-visible, FTIR, H¹NMR and C¹³NMR spectrometries. The oils were separated by conventional solubility techniques and were further fractionated into eight fractions (saturated, monoaromatic, diaromatic, triaromatic and poliaromatic hydrocarbons, resins, asphaltenes and pre-asphaltenes). These fractions were characterized by capillary gas cromatograpy with flame ionization detection and gas chromatography/mass spectrometry. Data obtained from simulated distillation of the oils provided useful information regarding product quality.     

SEVERE BIODEGRADATION OF CRUDE OILS FROM THE QUIRIQUIRE FIELD,EASTERN VENEZUELAN BASIN

Five crude oil samples from the Quiriquire field (Maturin sub-basin, Eastern Venezuelan Basin) were analysed to evaluate their levels of biodegradation. The oils were obtained from coarse sandstones and conglomerates of the Pliocene Quiriquire Formation at depths <1000 m. Analyses of the samples’ bulk physicochemical parameters indicate variations in API gravity and in the content of saturated hydrocarbons and NSO+asphaltenes, and also in the saturate/aromatic ratio which increases in more biodegraded oils. n-Alkane distributions are characterized by a dominant unresolved complex mixture (UCM) or hump under an envelope of peaks which lack the acyclic isoprenoids pristane and phytane. The alteration of steranes and terpanes together with the presence of 25-norhopanes and 17-nor-tricyclic terpanes, and the alteration of low molecular-weight (C₂₀-C₂₁) triaromatic steroids, phenanthrene, methyl-phenanthrene, dibenzothiophene and methyl-dibenzothiophene, indicate that the oils have undergone severe biodegradation. The oils contain compounds with different susceptibilities to biodegradation which is probably a consequence of the mixing of different oil charges in the Quiriquire Formation reservoir. The oils were derived from underlying source rocks in the Upper Cretaceous Guayuta Group (Querecual and San Antonio Formations), and migration into the shallow reservoir at Quiriquire field likely occurred continuously through time. Although the oils have undergone severe biodegradation, it was possible to make some inferences about their origin. Thus, the analyzed oils are interpreted to have originated from marine shale or marl source rocks containing mixed organic matter deposited under anoxic-suboxic conditions and were generated at near peak oil window maturities.     

DISTRIBUTION OF BIOMARKERS IN HIGHLY WEATHERED PETROLEUM RESIDUE FROM MEDITERRANEAN WATERS

The aliphatic and aromatic fractions of a beach tar sample from the Mediterranean coast of Sidi Kreir, 37Km west of the city of Alexandria was analyzed by GC and GC/MS techniques. A complete analysis was carried out to investigate chemical composition changes, fate of weathered oil residue and possible source identification. The distribution of sterane, hopane, mono-and triaromatic steroids, C₂ - and C₃ - phenanthrenes and dibenzothiophenes and chrysenes, however, had remained unaltered by weathering. The beach tar possessed geochemical features consistent with a marine carbonate or evaporite source depositional environment under normal saline, reducing conditions. The GC fingerprints pointed to heavy fuel oil as a possible source for the tar sample.     

Changes Associated with Field-Scale Demonstration in a Steam-Stimulated Crude Oil from the Lagunillas Oilfield (Lake Maracaibo,Venezuela)

Abstract

Cyclic steam injection with alkali is currently very commonly used to improve heavy-crude oil production in Venezuela. This work is an analysis of oil-associated water and crude samples from LL-2670 well in the Lagunillas oilfield at Lake Maracaibo (northwestern Venezuela). The aim of this research is to analyze the organic acids thus generated and evaluate chemistry changes in the saturated and aromatic fractions of crude oil during the first cycle of steam stimulation by cyclic injection with alkali. It was noted that the percentages of sulfur and saturates, aromatics, resins, and asphaltenes (SARA) and the American Petroleum Institute (API) gravity varied little in the analyzed crude. In contrast, there were significant variations in the biomarker distribution, particularly in the mono- and triaromatic steranes, benzothiophenes, phenanthrenes, and alkyl-naphthalenes of the crude.     

南襄盆地泌阳凹陷西部稠油地化特征及意义

精细刻画稠油地球化学特征,对其油源对比、成因乃至开发都具有一定指导作用。南襄盆地泌阳凹陷西部地区原油均遭受了中等以上级别的生物降解,规则甾烷和藿烷受到不同程度破坏,使得一些反映原油成因、成熟度的常用指标严重失效。通过对该区12个稠油样品地球化学特征的精细分析和研究,发现饱和烃中的伽马蜡烷、Ts、Tm以及长链三环萜烷的抗降解能力高于规则甾烷和藿烷,能较好地反映该区稠油地球化学特征。油源对比表明,该区核三下段原油均来源于核三下段烃源岩,而核三上段原油除来源于核三上段烃源岩外,不同小层段都有核三下段源岩不同程度的贡献。结合芳烃组成特征和参数,可以清楚地将研究区稠油划分成两类,并显示他们可能具有不同的生物降解机制。     

BIOMARKER CHARACTERISTICS OF CRUDE OILS FROM THE MURZUQ BASIN,SW LIBYA

Twenty crude oil samples from the Murzuq Basin, SW Libya (A‐, R‐ and I‐Fields in Blocks NC115 and NC186) have been investigated by a variety of organic geochemical methods. Based on biomarker distributions (e.g. n‐alkanes, isoprenoids, terpanes and steranes), the source of the oils is interpreted to be composed of mixed marine/terrigenous organic matter. The values of the Pr/Ph ratio (1.36–2.1), C₃₀‐diahopane / C₂₉ Ts ratio and diasterane / sterane ratio, together with the low values of the C₂₉/ C₃₀‐hopane ratio and the cross‐plot of the dibenzothiophene/phenanthrene ratio (DBT/P) versus Pr/Ph ratio in most of oil samples, suggest that the oils were sourced from marine clay‐rich sediments deposited in mild anoxic depositional environments. Assessment of thermal maturity based on phenanthrenes, aromatic steroids (e.g. monoaromatic (MA) and triaromatic (TA) steroid hydrocarbons), together with terpanes, and diasterane/sterane ratios, indicates that crude oils from A‐Field are at high levels of thermal maturity, while oils from Rand I‐Fields are at intermediate levels of thermal maturity. Based on the distributions of n‐alkanes and the absence of 25‐norhopanes in all of the crude oils analysed, none of the oils appear to have been biodegraded. Correlation of the crude oils points to a single genetic family and this is supported by the stable carbon isotope values. The oils can be divided into two sub‐families based on the differences in maturities, as shown in a Pr/nC₁₇ versus Ph/nC₁₈ cross‐plot. Sub‐family‐A is represented by the highly mature oils from A‐Field. Sub‐family‐B comprises the less mature oils from R‐ and I‐Fields. The two sub‐families may represent different source kitchens of different thermal maturity or different migration pathways. In summary, the geochemical characteristics of oil samples from A‐, R‐, and I‐Fields suggest that all the crude oils were generated from similar source rocks. Depositional environment conditions and advanced thermal maturities of these oils are consistent with previously published geochemical interpretations of the Rhuddanian “hot shale” in the Tanezzuft Formation, which is thought to be the main source rock in the Murzuq Basin.     

川东北地区典型海、陆相原油地球化学特征及来源

基于饱和烃和芳烃组分的GC/MS和GC/MS/MS分析,揭示了川东北天然气勘探区探井及露头剖面中发现的典型海、陆相原油（油苗）的分子地球化学特征,并结合烃源岩分析资料探讨其来源。研究结果表明,大普光构造带的新清溪1井和元坝构造带的元坝9井中侏罗统千佛崖组原油饱和烃呈姥鲛烷优势（Pr/Ph>1.5）;三环萜烷很少,ETR值低于1.2;芳烃中芴系列含量高;经与相关烃源岩干酪根碳同位素组成的对比,确认两者油源均来自本层位湖相烃源岩。但这两井原油的重排藿烷类化合物丰度相差悬殊,表征两者油源岩性质有所不同。大普光构造带的川岳84井二叠系原油Pr/Ph值（0.82）较低,三环萜烷丰富,含有C₂₆降胆甾烷,油-岩对比认为来源于上二叠统龙潭组海相烃源岩。江油二郎庙飞仙关组、长兴组油苗呈显著的C₂₉甾烷优势,24-异丙基-/24-正丙基-胆甾烷比值较高（1.1）,C₃₀甲基甾烷中以3β-、2α-甲基甾烷为主,C₂₆甾烷中27-降胆甾烷占优势,芳烃中缺少三芳甲藻甾烷,且全油碳同位素很轻（-34.1‰～-34.6‰）,表明源于寒武系-震旦系烃源岩。     

DISTRIBUTION OF BIOMARKERS IN HIGHLY WEATHERED PETROLEUM RESIDUE FROM MEDITERRANEAN WATERS

ABSTRACT

The aliphatic and aromatic fractions of a beach tar sample from the Mediterranean coast of Sidi Kreir, 37Km west of the city of Alexandria was analyzed by GC and GC/MS techniques. A complete analysis was carried out to investigate chemical composition changes, fate of weathered oil residue and possible source identification. The distribution of sterane, hopane, mono-and triaromatic steroids, C₂ - and C₃ - phenanthrenes and dibenzothiophenes and chrysenes, however, had remained unaltered by weathering. The beach tar possessed geochemical features consistent with a marine carbonate or evaporite source depositional environment under normal saline, reducing conditions. The GC fingerprints pointed to heavy fuel oil as a possible source for the tar sample.     

反应时间对加氢残渣油四组分含量和结构的影响

以沙特轻质原油减压渣油（ALVR）为原料,采用高压釜考察了不同反应时间下加氢反应后残渣油的四组分含量及其结构组成变化。结果表明,与未加氢渣油相比,加氢残渣油中的饱和分含量大幅度增加,而芳香分、胶质和沥青质的含量均降低,四组分的H/C原子比和平均相对分子质量均降低,芳碳分率升高。加氢残渣油的四组分含量随反应时间的增加均呈规律性变化。随着加氢反应时间的增加,四组分的H/C原子比和平均相对分子质量降低,芳香分、胶质和沥青质的芳碳分率增加,胶质和沥青质的总环数和芳环数均降低。渣油加氢反应过程中,其四组分均发生了明显的氢解和脱烷基反应,胶质和沥青质结构单元间的各种桥键可发生明显的断裂,导致其结构单元数减少。不同来源和属性的渣油加氢反应后各组分的结构变化有一定区别。     

应用芳烃,中性氮馏分研究油藏原油注入史

油藏中原油的成分经常是非均质性的，这种现象在低渗透油田更为明显。它可起因于原油的充注效应和运移过程，亦可源于原油在油藏中的次生化学变化。芳烃馏分和中性含氮化合物运移参数的分布表明，该油藏原油是自东而西注入的。     

Geochemical characterization of aromatic hydrocarbons in crude oils from the Tarim,Qaidam and Turpan Basins, NW China

Based on the systematic study of aromatic hydrocarbons in over 100 crude oil samples collected from the Tabei and Tazhong uplifts in the Tarim Basin, the western depression area in the Qaidam Basin and the Tabei depression in the Turpan Basin, the geochemical characteristics of the marine (Tarim Basin), saline lacustrine (Qaidam Basin), and swamp (Turpan Basin) oils were investigated. The marine oils from the Tarim basin are characterized by relatively low abundance of diaromatic hydrocarbons such as biphenyl and naphthalene, and relatively high abundance of triaromatic hydrocarbons including phenanthrene, dibenzothiophene and fluorene. In contrast, the swamp oils from the Turpan Basin are dominated by the highest relative abundance of diaromatic hydrocarbons and the lowest relative abundance of triaromatic hydrocarbons in all the oil samples in this study. The relative abundance of diaromatic and triaromatic hydrocarbons in the saline lacustrine oils from Qaidam Basin is between that in Tarim oils and Turpan oils. Aromatic parameters based on the isomer distributions of dimethylnaphthalenes (DMN), trimethylnaphthalenes (TMN), tetramethylnaphthalenes (TeMN) and methylphenanthrenes (MP), i.e., 1,2,5-trimethylnaphthalene(TMN)/1,3,6-TMN ratio, 1,2,7-TMN/1,3,7- TMN ratio, (2,6- +2,7-)-dimethylnaphthalenes (DMN)/1,6-DMN ratio, 1,3,7-TMN/(1,2,5- +1,3,7-)-TMN, 1,3,6,7-TeMN/(1,3,6,7- +1,2,5,6- +1,2,3,5-)-TeMN ratio and MP index, may reflect the diversity of organic source input, thermal maturity and depositional environments. In addition, the dibenzothiophenes (DBTs)/fluorenes(Fs) and dibenzofurans (DBFs)/Fs ratios were found to the very useful and effective in determining genetic types of crude oils for the marine, saline lacustrine, and swamp depositional environments, and for oil-oil correlations.