油层不同开采时期原油组分变化特征

运用有机地球化学分离、分析技术对取自塔里木盆地的东河、塔中和轮南油田不同时期开采出的原油样品进行剖析,研究其宏观组成和微观分子在时空上的变化规律。分析结果表明,原油饱 /芳比值随开采时间的推移呈下降的趋势;饱和烃与非烃 +沥青质的含量变化有很好的相关性。随着开采时间的增长,原油中正构烷烃的主峰碳数后移,原油的轻 /重组分比降低。原油碱性氮、有机酸等非烃类化合物随开采时间的推移也呈降低的趋势。这些变化与原油在驱替过程中的自然色层吸附作用机理和原油中各种组分的相互作用关系有关。该项研究对于深入探索驱油机理、预测原油润湿性和提高采收率具有重要的实际意义。     

Solid bitumens: an assessment of their characteristics, genesis, and role in geological processes

Familiar since antiquity, and subject in contemporary times to various characterization schemes, the exact nature of solid bitumen is not yet fully known. Bitumens have ‘random polymer-like’ molecular structures, are mobile as highly viscous fluids or were once fluids but have since turned into solids. Solid bitumens consist mainly of large moieties, of polyclyclic aromatic hydrocarbons, occasionally with finely admixed, fine-grained cryptocrystalline graphite. Solid bitumens are distinguished from kerogen, which is the syngenetic and generally finely dispersed particulate organic matter in sedimentary rock that virtually does not migrate following its deposition. Occurrences of solid bitumens are relevant to petroleum exploration as well as the search for, and evaluation of, a variety of metallic mineral deposits. Genesis of bitumen is in many cases linked to the thermal and hydrothermal history of organic matter in sedimentary rock. Apparently bitumen, or more specifically organic acids generated along with bitumen during diagenesis, may alter porosity of reservoir rocks or otherwise prepare the ground for ore deposition. Bitumen is also relatively sensitive to alteration processes, some of which, such as oxidative weathering, water leaching, biodegradation (contact) metamorphism and ionizing radiation may likewise affect its nature. Elemental composition of bitumen commonly reflects the nature of mineral deposits. Is is possible that in petroleum exploration, trace metal abundances of bitumen may eventually allow prediction of crude oil types and volumes anticipated from a given source rock? Beside transition elements, notably Ni and V, highly anomalous concentrations of U, Pt and Au occur in some solid bitumens. During the generation of petroleum from kerogen, the trend in δ¹³C is toward lighter values. The opposite seems to occur when liquid petroleum is subjected to thermal cracking (and /or related processes) yielding solid bitumen enriched in ¹³C, and isotopically light methane. In fact, except for deasphalting and possibly some irradiation processes, the result of thermal cracking, oxidation, water leaching, inspissation (drying) and bacterial degradation of crude oil is that lower molecular weight hydrocarbons are removed leaving bitumen residues enriched in aromatic hydrocarbons, heteroatomic compounds (NSO) and ¹³C. Such phenomena are relevant to bitumen paragenesis in petroleum reservoir rocks, to certain Phanerozoic occurrences of multiple generations of bitumens, and to bitumens in mineral deposits.     

Evidence for bacterial degradation of hydrocarbons in uranium deposits

The biodegradation of free hydrocarbons migrated in reservoir faaes has often been observed in petroleum exploration. This bacterial alteration is characterized by the progressive removal of different classes of hydrocarbons. One of the most important consequences of biodegradation is the reduction of sulphate, as noted in several Pb-Zn deposits. Biodegradation of oils spatially associated with uranium deposits has also been observed in Lodeve (France), Grand Canyon (Arizona, USA), Temple Mountain (Utah, USA) and leads to the transformation of fluid oils into solid bitumens. Within this study emphasis has been laid on the relationships between the effects of biodegradation on organic matter (oxidation or aromatization) and the nature of aqueous solutions analysed in fluid inclusions trapped in authigenic minerals. Different mechanisms are proposed to explain the transformations of organic matter during biodegradation and their possible links with ore-forming processes.     

不同采出程度下石油组分变化特征

利用GHM烃分析仪对水驱模拟实验过程中不同阶段的采出原油进行分析,研究其原油组成的变化规律,探索原油组成与采出程度之间的内在关系。实验表明 :原油的采出程度与采出流体PV数之间具有良好的对应关系;随着采出程度逐渐提高,原油中正构烷烃的碳数范围及主峰碳数逐渐后移,原油的轻 /重比值呈现降低趋势。实验还证明,某些在空间上呈圆柱型、具有规则支链的分子比相近碳数的直链分子更容易被驱出。该项研究对于从微观角度深入探索驱油机理、提高原油采收率具有实际意义。     

辽河油田稠油中贵金属分布和赋存状态研究

以辽河油田稠油为研究对象,通过原子吸收光谱、实沸点蒸馏等手段,研究了辽河油田稠油中Au、Ag、Pt和Pb等贵金属在不同馏分中的分布特征.结果表明,经过实沸点蒸馏后,贵金属不同沸程温度的原油馏分中含量和分布存在很大差异,Au、Ag、Pt、Pd主要集中在渣油馏分中,在沸点》508℃的渣油馏分中Au、Ag、Pt、Pd的比例分别是93.4%、76.9%、73.4%和68.0%;采用选择性萃取的方法对金在稠油中的存在形态的初步研究发现,金在稠油中主要以有机配合物和少量无机配合物形式存在.     

准噶尔盆地西北缘车排子凸起原油类型与油源

准噶尔盆地西北缘南部红车断裂带- 车排子凸起油气藏众多,原油物理化学性质和地球化学特征十分复杂,原油类型及其来源长期存在很大争议。本文在准噶尔盆地不同时代烃源岩生成原油典型地球化学特征与主要油源判识指标归纳总结的基础上,对红车断裂带- 车排子凸起原油地球化学特征和来源进行系统分析研究,将该区域原油分为五类,其中三类原油分别来源于二叠系湖相烃源岩、中—下侏罗统煤系烃源岩、古近系安集海河组湖相烃源岩,另外两类为混合原油,分别为来源于二叠系湖相烃源岩的生物降解稠油与中—下侏罗统煤系烃源岩生成的正常原油和古近系湖相烃源岩生成的正常原油的混合原油。红车断裂带石炭系—白垩系油藏原油主要来源于沙湾凹陷二叠系湖相烃源岩,车排子凸起东北部春风油田稠油来源于沙湾凹陷二叠系湖相烃源岩;车排子凸起东侧- 红车断裂带西侧新近系沙湾组油藏轻质原油来源于四棵树凹陷古近系湖相烃源岩;车排子凸起中部春光油田白垩系—古近系油藏稠油为二叠系来源稠油和侏罗系正常原油的混合原油,新近系沙湾组油藏稠油为二叠系来源稠油与新近系正常原油的混合原油;车排子凸起西部石炭系—古近系油藏轻质原油来源于四棵树凹陷中—下侏罗统煤系烃源岩,而新近系沙湾组油藏轻质原油来源于四棵树凹陷古近系湖相烃源岩。本文对准噶尔盆地西北缘南部地区油气藏成藏研究及区域油气勘探决策具有重要参考作用。     

沉积盆地中金属成矿与油气成藏的耦合关系

沉积盆地中与油气密切相关的金属矿床主要包括密西西比河谷型(MVT)铅锌矿床、砂页岩型铜-铀矿床、黑色页岩中的金属硫化物矿床、沉积岩容矿的金-锑-砷-汞-铊矿床等。金属矿床与(古)油气藏在空间上的密切共生/伴生关系,暗示了二者成因上的有机联系。在许多MVT铅锌矿床和砂页岩型铜矿床中,与成矿关系密切的原油及其衍生物形成于矿化前,它们为随后的金属成矿直接提供还原硫或充当硫酸盐还原反应的还原剂。在另一些情况下,某些低温热液金属矿床,特别是Au、As、Hg、Sb、Tl矿床与油气表现出同源、同运、同聚的耦合关系,金属成矿与油气成藏同时或近同时进行。与油气具不同耦合关系的金属矿床常表现出不同的特点。与成藏和/或成矿有关的盆地流体大致可分为以碳氢化合物为主的有机流体、以含金属盐水溶液为主的无机流体以及同时富含烃类和金属组分的有机成矿流体3类,盆地中的成矿、成藏作用及其耦合关系受控于这三类流体的演化过程。沉积盆地中金属矿床与油气藏空间上密切的共生/伴生关系以及成矿、成藏过程和机理的相似性,使金属与油气矿产资源的协同勘探和综合预测成为可能。     

A review of the occurrences and causes of migration-contamination in crude oil

Migration-contamination occurs when a migrating or trapped crude oil functions as a solvent, dissolving molecular components from the syndepositional organic matter of the migration conduit and/or the reservoir rock. This review documents the causes and worldwide occurrences of migration-contamination, and suggests methods of identifying the signatures of this phenomenon within the molecular and isotopic composition of crude oils. Instances of migration-contamination have been identified in oils of Australia, Asia, Africa and North America, and are best identified by the presence of molecular and/or isotopic imbalances in the oil. Such imbalances are most apparent when co-occurring molecular suites are incompatible with one another, particularly in terms of thermal maturity. Occurrences of migration-contamination in oils of the US Gulf of Mexico—documented by molecular maturity imbalances such as the presence of unsaturated hydrocarbons known to be unstable at petroleum generation temperatures—provide the best examples of this phenomenon. An attempt is made to quantify the extent and impact of this process in the Vermilion 14 field, offshore Louisiana in the US Gulf of Mexico. Here, molecular maturity markers in the migrated fluid and in the syndepositional organic matter of the reservoir rocks are compared, and the proportion of contamination in each reservoired fluid is estimated. Examples such as this may assist in explaining maturity anomalies observed in several oils worldwide, particularly in Tertiary-reservoired oils that have migrated through, and are trapped in, thermally immature sediments. It is suggested that the low molecular maturity ratios often observed in Tertiary-reservoired oils and attributed to unusually high heating rates may be caused, at least in part, by migration-contamination.     

东疆地区原油芳烃地球化学特征及其意义

在对东疆地区(包括吐哈盆地和三塘湖盆地)原油饱和烃生物标志物地球化学特征研究基础上,对原油芳烃馏分进行全面分析及地球化学特征研究;通过深入剖析原油芳烃系列组成,明确东疆地区原油类型划分,根据烷基奈、"三芴"系列及卡达烯、惹烯等化合物的分布特征,进一步揭示三塘湖盆地石炭系原油母源沉积水体盐度低、还原性弱,成油母质中包含丰...     

On the depth,time and mechanism of origin of the heavy to medium-gravity naphthenic crude oils

Paraffinic crude oils are designated ‘primary’ because their composition is very close or identical to that of the hydrocarbons extracted from the corresponding oil source rocks. Heavy and medium-gravity naphthenic crude oils, on the other hand, typically are quite different compositionally from hydrocarbon mixtures in either mature or immature shales.The normal paraffin carbon number odd/even ratio 2C₂₉/(C₂₈ + C₃₀) of all the heavy to medium-gravity crude oils which could be analysed are in exactly the same range as is observed for the primary paraffinic crude oils, namely 0.95–1.42. The naphthene indices of the medium to heavy gravity naphthenic crude oils and of the primary paraffinic crude oils from the same area are identical or close. These facts are significant because both the n-paraffin carbon number odd/even ratio and the naphthene index of shale hydrocarbons are strongly depth and subsurface temperature dependent. The facts observed demonstrate beyond question that, in the same area, the paraffinic precursors of the heavy to medium-gravity naphthenic crude oils are generated and expelled in the identical depth range, and from the same mature relatively deep oil source beds as the primary paraffinic crude oils. Later, during and/or after a generally upward migration into oil reservoirs, the primary crude may be transformed compositionally into a naphthenic crude oil.In none of the five widely scattered oil basins studied are medium to heavy naphthenic crude oils found at temperatures greater than a limiting subsurface temperature. The abruptness of the temperature cutoff of the change in oil compositions in all five oil basins, as well as the average value of the cutoff temperature of 66°C (150°F), leaves no doubt that the mechanism of this crude oil transformation process is microbial.Optical activity, which was observed in narrow saturate hydrocarbon fractions of the 80–325°C range of all microbially transformed crude oils, but not in the primary untransformed oils, is strong additional evidence for the microbial nature of the crude oil transformation process. The observed optical activity is explained by the microbial digestion at different rates of optical antipodes present in the primary paraffinic crude oils.To gain perspective the vast scale of the microbial oil transformation process in nature is pointed out. Billions of tons of heavy to medium-gravity naphthenic crude oils, originating from the microbial transformation of primary paraffinic oils, are present in oil fields and tar sands all over the world.     

Bitumens associated with lead,zinc and flnorite ore minerals in North Derbyshire,England

A bitumen deposit in north Derbyshire, England, is described and studied using the techniques of gas chromatography, infra-red spectrophotometry and elemental analysis. The bitumens are associated with lead-zinc-fluorite ore minerals concentrated along an unconformable contact between the Carboniferous Limestone and the overlying shales. Three varieties of bitumen are distinguished and are compared with the dispersed bitumens in both the Carboniferous Limestone and the Edale Shales, with crude oils believed to be derived from these shales, and with inclusions in the hydrothermal mineral fiuorite, associated with the limestone-shale contact. One of the varieties recognized, a brittle brown solid, contains aliphatic hydrocarbons very similar to those of the shales and to those of the crude oils likely derived from these shales. The other two are a viscous oil and a brittle, black solid, which geologic evidence suggests were originally derived from the limestone. They contain a very complex mixture of aliphatic hydrocarbons quite different from those in the limestone, however. Aliphatic hydrocarbons isolated from fluorite, which is hydrothermally formed, in nearby massive deposits are almost identical to those of the limestone and shale. This observation indicates that alteration of the aliphatic hydrocarbons in the sediment by hydrothermal fluids is an unlikely explanation for the origin of the complex mixtures of hydrocarbons in the viscous oil and brittle, black solid. On the basis of indirect evidence of high nitrogen content, presence of unsaturated hydrocarbons, and suitability of the environment for bacterial growth, it is suggested that selective bacterial alteration of the aliphatic hydrocarbons is the main process responsible for their present composition. A geologic history for the deposit is postulated that involves a two-phase introduction of bitumens. Each phase is suggested to have begun as a pulse of warm saline fluids migrating along the shale-limestone unconformity passed through the topographic high at Windy Knoll. Microbial oxidation of the bitumens may have taken place during the deposition process or, more likely, as a recent secondary oxidation process.     

Field-ionization mass spectrometry: application to geochemical analysis

The thiourea adduct, thiourea non-adduct and aromatic fractions from a series of Alberta oil sand bitumens have been subjected to field ionization mass spectrometric analyses. Field ionization mass spectra feature little fragmentation and the molecular weight distributions of compounds in the fractions are readily obtained. Using this method, the various acyclic and cyclic saturated hydrocarbons and the hydrocarbon and thiophenic aromatic materials may be distinguished by compound type and number of carbon atoms. The effect of biodegradation on crude oils is illustrated in the results from the series of oil sand bitumens and their asphaltene pyrolysis products. Field ionization mass spectrometry is potentially an important new analytical tool in organic geochemistry.     

江汉油田原油和生油岩有机抽提物中过渡族微量元素特征及其石油地球化学意义

运用中子活化分析方法对江汉油田原油和生油岩有机抽提物中过渡族微量元素Sc、V、CrMn、Fe、Co、Ni、Zn等进行了重点研究,测定了这些元素的丰度值。研究了这些元素在原油和有机抽提物族组份:沥表质、非烃和芳香烃中的变化规律。在此基础上,讨论了这些微量元素的相关性,并运用它们的丰度比值对数分布和归一化对数分布,进行了油-源对比的尝试。     

Carbon isotope geochemistry of Paleozoic oils from Big Horn Basin

Twenty crude oils from Paleozoic reservoirs in the Big Horn Basin. Wyoming were fractionated into light hydrocarbons, saturates, monoaromatics. diaromatics, polyaromatics-and-polars. and asphaltenes. Amounts and isotopic composition of each fraction were found to be internally consistent with the degree of maturation of the oil. confirming the established single source origin for these oils. A variation of approximately three per mil in the carbon isotopic composition of the whole oil and individual fraction was explained as being caused by maturation. The isotope-type-curves for these oils, the variations in isotopic composition as a function of compound group-type, were not found to be as simple as commonly believed. Other alteration processes, such as migration and deasphalting, might have influenced the pattern of the isotope distributions among fractions. The conservative nature of mass balance and subsequent isotope flows among various fractions of crude oil showed that the maturation of crude oil consists of consecutive processes leading from larger and more polar components into smaller and less polar components culminating in natural gas. Calculations were made to project the amount of condensates associated with the crude oils, and the amount of natural gas which had been generated from crude oils of a given maturity.     

Waxes and asphaltenes in crude oils

High molecular weight (HMW) hydrocarbons (>C₄₀) and asphaltenes are important constituents of petroleum and can cause problems related to crystallization and deposition of paraffin waxes during production and transportation as well as in the formation of tar mats. However, traditional methods to isolate asphaltene fractions, by adding 40 volumes in excess of low boiling point solvents such as pentane, hexane or heptane, can produce asphaltene fractions which are contaminated with a significant amount of microcrystalline waxes (>C₄₀). The presence of these microcrystalline waxes in the asphaltene fractions has the potential to provide misleading and ambiguous results in modeling and treatment programs. The sub-surface phase behaviour of an asphaltene fraction will be quite different from that of a wax-contaminated asphaltene fraction. Similarly accurate modelling of wax drop-out requires information on pure wax fractions and not asphaltene-dominated fractions. Hence the goal of this paper is to describe a novel method for the preparation of wax-free asphaltene fractions. In addition, this method provides a quantitative subdivision of the wax fraction into pentane soluble and insoluble waxes which, when correlated with physical properties of crude oil such as viscosity, pour point, cloud point, etc., may help explain causes of wax deposition during production, transportation and storage of petroleum.     

C24–C27 Degraded triterpanes in Nigerian petroleum: novel molecular markers of source/input or organic maturation?

The analyses, by gas chromatography and gas chromatography/mass spectrometry, of the triterpane concentrate of crude oils sampled from various oil fields of the Tertiary Niger delta have revealed the ubiquitous presence of a series of C₂₄–C₂₇ tetracyclic alkanes likely to be novel degraded triterpanes. The presence in the crude oils of a C₂₅ tricyclic alkane, apparently structurally related to the tetracyclanes, seemed consistent with the hypothesis of sequential cleavages of the terminal rings of precursor pentacyclic triterpenoid derivatives with increasing thermal transformation of the respective petroleums.The degraded triterpanes might be useful for assessing the stages of thermal evolution of petroleum in the reservoir. A possible application, to oil exploration, of the expected variations in the concentration of the polycyclanes in crude oils with different thermal histories would be in distinguishing primary (immature) oils from mature but biodegraded oils.     

塔里木盆地原油的成因研究

对塔里木盆地原油和生油岩饱和烃进行ＧＣ－Ｃ－ＭＳ和ＧＣ－ＭＳ分析，利用单个正构烷烃碳同位素组成和三环萜烷分布特征进行油源对比，研究了塔里木盆地原油的油源问题；根据寒武—奥陶系富含菌藻有机质生油岩饱和烃色谱分析结果，对塔里木盆地海相原油含蜡较高的成因进行了探讨     

滇西北兰坪金顶可能的古油气藏及对铅锌大规模成矿的作用

滇西北兰坪中—新生代沉积盆地产有中国最大的铅锌矿床,巨量铅锌矿石集中产在金顶穹窿内,矿石中不同产状的干酪根、轻质原油、重油、烃类气、沥青等多种成熟形式的有机物质丰富。对矿区有机物质进行了岩相学、生物标志化合物、碳同位素及铅同位素分析,结果显示：有机物质中氯仿沥青“A”的质量分数为（72～395 415.42）×10^-6,w（饱和烃）/w（芳香烃）普遍大于1,饱和烃中检测出丰度较高的正构烷烃、Pr、Ph和iC18等生物标志化合物,烃源母质为藻类生物Ⅰ型有机质;相对于区域岩石,矿石中有机物质的有机转化率较低（0.5%～7.2%,平均为3.05%）,已明显受热而成熟;透射全色光和紫外光显微镜在矿石光薄片样品中鉴别出较多原油和烃类气体包裹体。研究表明：金顶穹窿具有油气成藏“生、运、储、盖、闭”等配套发育的良好条件,矿区油气显示和古油气藏遗迹明显,铅锌成矿前或成矿中可能已形成油气藏;这个可能的油气藏以富含原油、烃类和H2S等还原性气体为成分特征;金顶古油气藏中H2S等还原性气体的聚集及其导致铅锌硫化物快速集中沉淀是大规模成矿的关键,成藏—成矿是金顶穹窿中一个连续发生、发展的动力学过程,成藏是成矿的前提。     

Factors controlling the proportionality of vanadium to nickel in crude oils

The proportionality of V to Ni in crude oils is determined by the environmental conditions in which their source rocks were deposited. Thermal maturation, migration, and reservoir alterations may change the concentrations of these two metals by addition or subtraction of more labile portions of a crude oil, but their tenacious bonding with high-MW organics suggests that their proportionality to one another should remain unchanged. Eh-pH diagrams offer an explanation of the factors controlling their proportionality and its relationship with S contents. Three Eh-pH regimes are proposed for the natural system. Regime I represents conditions under which Ni⁺² is available for bonding and vanadium is unavailable because of its quinquivalent state. Crude oils expelled from source rocks deposited within this regime are expected to have $\text{V}\text{(Ni + V)}$ less than 0.10 and low S (<1 weight percent). Regime II represents conditions under which Ni⁺²-Nickelous cations and vanadyl cations are available with vanadyl cations being hindered in part by the formation of hydroxides and nickelous cations being hindered in part of metastable sulfide ions. Source rocks deposited within this regime expel crude oils with low S contents and V-Ni fractions that range from 0.10 to 0.90. Regime III represents conditions under which vanadyl and trivalent vanadium cations are available for bonding but Ni⁺² may be partially hindered by sulfide complexing. Source rocks deposited within this regime expel crude oils that have high S contents and V-Ni fractions greater than 0.50.     

Geochemical characteristics of crude oil in fluvial deposits from Maling oilfield of Ordos Basin,China

Maling oilfield is one of the earliest discovered oilfields in the Ordos Basin. It is also a typical representative of oil reservoirs in fluvial deposits. However, due to the deficiency of geochemical study on the crude oils and source rocks, the interpretation of the oil origin is largely based on the geological situation. Maling crude oils (21) and source rocks (14) from the basin have been systematically analyzed. The distribution of the biomarkers indicates that the crude oils mainly originated from source rocks deposited under a weakly reducing to sub-oxic, freshwater lacustrine environment. Besides algae, higher land plants have also made an important contribution to the source organic matter. Comparison of the distributions of the biomarkers suggests that there is a correlation between the Maling oilfield oils and the source rocks of the Yanchang Formation.