Origin of hydrocarbons in triassic serpiano oil shales: Hopanoids

The hydrocarbons in the sapropelic Serpiano oil shales have been examined. The hopanoids are the most predominant hydrocarbons present in the bitumen, with hopanes, hopenes, benzohopanes and monoaromatic secohopanoids being detected. The novelty of the Serpiano hopanoid assemblages lies in the occurrence of high concentrations of methylhopanoids. The distributions of the hopanoids and of their corresponding methylhopanoids are remarkably similar. This similarity was also observed for the hopanes and methylhopanes which were generated from the asphaltene and kerogen by hydrous pyrolysis, and is indicative of a common biosynthetic pathway.     

Detection of alkylated fluorenes in Athabasca oil sand bitumens

Athabasca oil sand aromatic fractions were subjected to base-catalyzed autoxidation to selectively oxidize fluorenes to fluoren-9-ones and to 9-alkylfluoren-9-ols. Owing to differing polarities, the oxidation products could be separated conveniently by column chromatography to yield a series of mono- to tetramethylfluoren-9-ones, 9-n-alkylfluoren-9-ols and their nuclear methylated derivatives which were previously detected in Alberta bitumen resins.In the samples analyzed, 1,4-dimethylfluorene was present as the major nuclear dimethylated fluorene along with minor amounts of the 2,4- and 3,4-dimethyl isomers. 2,4-Dimethylfluorene was found in one sample but was absent in the other. 9-Methylfluorene was the major 9-alkyl compound present. Individual members of these series were identified by comparison of capillary gas chromatographic retention times and mass spectra with those of synthetic standards.It is suggested that the fluorenes are the source of fluorenones and fluorenols in Athabasca oil sand. The reservoir may have experienced mildly oxidative conditions at some time.     

原油裂解过程中固体沥青的拉曼光谱演化特征

固体沥青是石油天然气的伴生产物,它记录了油气藏演化过程中的重要信息。本文通过原油裂解模拟实验得到不同成熟度条件下的固体沥青,并利用激光拉曼光谱仪对其进行测定。测定结果表明,拉曼光谱中的D峰随着成熟度的增加总体呈现出向低波段移动的趋势,G峰没有明显的变化趋势,已有的拉曼参数(如G峰与D峰的拉曼位移和面积比)也随着成熟度的增加发生了规律性的变化,为实际地质条件下固体沥青的拉曼光谱特征研究提供了科学的实验依据。     

An NMR survey of United States oil shales

Solid state nuclear magnetic resonance techniques were used to measure the fraction of aliphatic carbon in oil shales from United States deposits, ranging in age from Ordovician to Tertiary. The aliphatic carbon fraction was shown to correlate with the fraction of organic matter converted to oil during Fischer assay. The fraction of organic matter convertible to oil is a primary factor in evaluating the oil potential of an oil shale resource. Nuclear magnetic resonance determines this in a nondestructive, easily interpreted bulk analysis of the whole rock.     

Aliphatic hydrocarbons in coastal sediments of the Northern Cyprus (Eastern Mediterranean)

The sources and spatial distributions of aliphatic hydrocarbon concentrations were investigated in surficial sediments of the Northern Cyprus (Gemi Konagi, Girne and Gazi Magusa Areas). Aliphatic hydrocarbon levels were determined with a gas chromatography–mass spectrometer. Total aliphatic hydrocarbon (n-alkanes, Σ25; isoprenoids, Σ2) concentrations in the sediments were found in the range of 1107–6360 ng/g. Results indicated that the sediments were mainly dominated by odd numbered n-alkanes (n-C10–n-C34), maximizing at n-C17, n-C29 and n-C31. Statistical analyses and diagnostic ratios have been used to determine the possible sources and origins of aliphatic hydrocarbons. Aliphatic hydrocarbons were showed biogenic character at all sampling areas and were found mainly originated from terrestrial, marine and both terrestrial-marine plants at Gemi Konagi, Gazi Magusa and Girne, respectively.     

Organic matter and deposition conditions of the Kashpir oil shales

The composition of organic matter was investigated in the oil shales and country rocks of the Kashpir deposit. The analysis of the aromatic fraction of bitumen showed the presence of isorenieratene derivatives, which indicates the accumulation of the sequence under anoxic conditions in the bottom waters of a paleobasin. Special attention was given to the composition of organosulfur compounds from the bitumen of rocks and products of kerogen pyrolysis. The concentrations of hydrocarbon structures occurring in the bitumen in a free state and in sulfur-bearing derivatives are comparable. The composition of the pyrolysis products of kerogen depends on the concentration of organic carbon in the rock: carbon-rich rock varieties contain kerogen whose pyrolysis yields relatively high concentrations of organosulfur compounds and low total contents of n-alkanes/n-alkenes-1.     

中国陆相油页岩特征及成因类型

中国油页岩资源丰富,以陆相沉积为主,主要赋存于中新生界,颜色通常为黑色-深灰色和灰褐色-棕褐色,且富矿油页岩一般比贫矿油页岩的颜色深.油页岩中矿物成分以石英、长石和黏土矿物为主,黏土矿物中高岭石含量相对较高.中国陆相油页岩总体质量特征为中等偏好,含油率大于5%的页岩油资源占67.64% ,灰分产率一般为53.27% ～84.35% ,多属高灰分油页岩.发热量各地区差别较大,最小值为4.19 MJ/kg,最大值可达34.60 MJ/kg,而且同一地区不同层位的油页岩发热量也不相同.就伴生元素而言,油页岩中富含大量的稀土元素和微量元素,使油页岩具有巨大的综合利用潜力.从有机成因角度,中国陆相油页岩可以分为腐泥型油页岩、腐殖腐泥型油页岩和腐泥腐殖型油页岩;从油页岩的沉积环境成因角度,可以划分为拗陷湖成油页岩、断陷湖成油页岩和断陷湖泊-沼泽油页岩;从油页岩形成的水体性质角度,可以划分为淡水油页岩和半咸水油页岩.中国陆相油页岩中湖泊-沼泽油页岩一般与煤伴生,多为腐殖腐泥型油页岩和腐泥腐殖型油页岩;而湖成油页岩一般单独存在或为煤层顶板,多为腐泥型油页岩和腐殖腐泥型油页岩.     

Organic geochemistry and petrography of Lower Cretaceous Wealden black shales of the Lower Saxony Basin: The transition from lacustrine oil shales to gas shales

Ninety-seven Wealden black shale samples from three wells in the Lower Saxony Basin have been studied by organic geochemical and organic petrographical methods to determine their maturity, organic facies and depositional environment. The maturities of the three wells range from early mature (Ex-A), late to postmature (Ex-C) to overmature (Ex-B) as determined by vitrinite reflectance measurements, diamondoid ratios and other geochemical maturity parameters. Ex-C and Ex-B show distinct petrographic features related to oil generation and migration. In particular, the occurrence of dispersed solid bitumen replacing initial type I kerogen suggests a formerly active petroleum system. Structural and textural differences between early mature alginites and solid bitumen in postmature to overmature samples show an alteration of the pore system with increasing maturity. A freshwater depositional environment is indicated by widespread occurrence of botryococcus algae and other small alginite particles predominating in the immature well. These alginites are absent in the more mature gas shales of wells Ex-C and Ex-B. Geochemical evidence of algae and phytoplankton in general is provided by numerous biomarker parameters, while the occurrence of β-carotane in some samples indicates events of increased salinity, although no hypersaline conditions are inferred due to very low gammacerane indices. Increased amounts of vitrinite and inertinite in samples of Ex-B suggest locally significant terrigenous input of organic matter for some periods during Wealden Shale deposition. High sulfur/organic carbon ratios provide evidence for sulfate rich waters and (partly) anoxic bottom water conditions. While the lower mature lacustrine source rocks generate paraffinic/waxy oils, gas and condensates are produced at post-mature stages. Furthermore, maturity distribution maps from 3D numerical petroleum systems modeling reveal substantial differences in respect to petroleum generation.     

藏北高原海陆相油页岩生物标志化合物对比研究

重点报道了藏北高原双湖地区早侏罗世海相油页岩和可可西里地区中新世陆相油页岩生物标志化合物组合差异.在两套油页岩中均检出丰富的正构烷烃、类异戊二烯烷烃、萜类化合物及甾类化合物,但二者生物标志化合物组合明显不同.这种不同是在有机质演化程度差异的基础上,主要由原始生物输入和沉积环境差异造成的.海相油页岩正构烷烃具有低碳数优势, nC15、nC16或 nC17为主峰碳,无明显的奇偶碳数分布, Pr/Ph比值显示,多数海相油页岩具有姥鲛烷优势,缺乏β-胡萝卜烷,伽马蜡烷含量较低,海相油页岩原始有机母质构成中,既有丰富的菌藻类等低等水生生物,还有一定比例的陆生高等植物混合输入的特点,属贫氧-缺氧、弱氧化-弱还原沉积环境,进一步证明了早托尔期这种富碳缺氧黑色油页岩是一次全球性海平面上升事件的产物.陆相油页岩正构烷烃具有高碳数优势,主峰碳数为 nC23或 nC29,奇碳数优势突出, Pr/Ph比值显示,陆相油页岩具有强烈植烷优势,β-胡萝卜烷含量相对较高,伽马蜡烷 /αβ C30霍烷比值为 0.31～ 0.60,陆相油页岩原始有机母质构成中,既有高含量的高等陆生植物,还有一定数量低等水生生物混合输入,且在剖面序列中有由早期 C3型陆生高等植物向晚期 C4型转变,特别是剖面顶部油页岩中具有丛粒藻 Botryococus输入的特点,从而导致罕见的重δ13C异常,属缺氧、强还原湖泊沉积环境,反映了晚中新世湖泊演化历史中生态系统的转型和更新这一重要事件.古湖泊演化早期具有水体盐度分层,以出现高含量的β-胡萝卜烷和伽马蜡烷为标志,为咸水湖,晚期湖平面上升,湖泊水体盐度逐渐降低.     

北羌塘盆地油页岩形成环境及其油气地质意义

最近在北羌塘长蛇山地区新发现了晚侏罗世—早白垩世大套油页岩及巨厚膏盐层,该油页岩与近年来作者在胜利河、长梁山地区发现的多处油页岩连成一片,构成了目前我国规模最大的中生代海相油页岩带—北羌塘油页岩带。沉积岩相、古地理研究表明,晚侏罗世—早白垩世时期,北羌塘盆地总体上为一个向北西开口的相对闭塞的巨大海湾,发育了河流-三角洲、海湾(潮坪-潟湖)和浅海-陆棚等沉积相组合。古气候、古环境研究表明,油页岩(段)沉积期,胜利河地区处于潮湿的热带-亚热带环境,大量淡水的注入以及高的生产力等综合因素,控制了油页岩的形成,其分布主要位于局限海湾-潟湖的边缘带;膏盐层(段)沉积则发育于相对干旱、炎热气候条件下的闭塞环境。北羌塘晚侏罗世—早白垩世油页岩及其上覆膏盐层是重要的烃源岩和区域性封盖层。油页岩及含膏盐层沉积组合的发现,对于重新认识羌塘盆地生烃条件及保存条件,具有十分重要的意义。     

乌干达Albertine地堑含沥青砂岩的发现及其地球化学意义

Albertine地堑是乌干达共和国具有油气勘探潜力的中新生代断陷，通过野外考察及对采集样品的地球化学分析及综合研究，对该地堑的油气潜力有了一些初步认识，油－油对比表明，Paraa和Kibiro油苗具有相似的生烃源岩，而且烃源岩母质类型较好，含丰富的淡水灌类，Kivuku油苗母质类型较差，以陆生高等植物输入为主；油苗应源自5白垩系或下敏感系地层中的某一套烃源岩；2块含沥青砂岩具有相同的有机质来源,以陆源有机质输入为主，且明显不同于油苗，可能来自上敏感系地层本身，即该地堑至少存在两套成熟烃源岩，成熟度分析表明，Paraa和Kibiro油苗成熟度较高，为烃源岩在生烃高峰期的产物；Kibuku油苗成熟度稍低，为烃源岩在生烃高峰前的产物；含沥青砂岩成熟度低于油苗；沉积环境分析表明，该地暂沉积环境变化较大，特别是沉积水体的咸度变化较大，油苗的原始母质为淡水湖相沉积，Kibiro地区的生烃凹陷水体较深，淡水藻类发育；Kibuku地区生烃册陷水体较浅，陆生植物繁盛，含沥青砂岩的原始母质为咸水沉积环境。     

Analysis of the organic matter of oil shales by nuclear magnetic resonance

¹³C NMR spectroscopy was applied in the investigation of the structure of the organic matter in oil shales. By using Proton Enhanced Nuclear Induction Spectroscopy, a fair resolution of aliphatic and aromatic carbon signals was achieved. This method provided information on the relative ratio of aliphatic and aromatic carbons within a given set of samples (Aleksinac, Kimmeridge, Colorado, Australian torbanite and Estonian kukersite).     

Tri- and tetraterpenoid hydrocarbons in the Messel oil shale

The high molecular weight constituents of the branched and cyclic hydrocarbon fraction of the Messel oil shale (Eocene) have been examined by high resolution gas chromatography and combined gas chromatography-mass spectrometry. The following compounds are present: perhydrolycopene (1; lycopane), together with one or more unsaturated analogues with the same skeleton; a series of 4-methylsteranes (2c) in higher abundance than their 4-desmethyl analogues; two series of pentacyclic triterpanes, one series (C₂₇-C₃₂) based on the hopane structure (3a-e), and the other (C₂₇-C₃₁) based on the 17α-H hopane structure (3a-d, 17αH); and an intact triterpene hop-17 (21)-ene [3c, Δ 17(21)]. Only two additional triterpanes were detected in minor concentrations, viz. 30-normoretane (3b, 21αH) and a C₃₁ triterpane based on the hopane/lupane-type skeleton. The presence of these compounds suggests a significant microbial contribution to the forming sediment. Comparison of the tri- and tetraterpenoid hydrocarbons with those of the Green River Shale indicates differences in the organisms contributing to the two sediments.     

The occurrence of bisnorhopane,trisnorhopane and 25-norhopanes as free hydrocarbons in some Australian shales

The triterpenoid hydrocarbons of some West Australian shales have been examined by GC-MS. In addition to the common 17α(H),21β(H)-hopanes, 17β(H),21β(H)-hopanes and 17β(H),21α(H)-moretanes, 28,30-bisnorhopane, 25,28,30-trisnorhopane and 25-norhopanes were identified in the organic extracts. In contrast, pyrolysates of the solvent-extracted sediments contained only the common hopane and moretane series, indicating that 28,30-bisnorhopane, 25,28,30-trisnorhopane and 25-norhopanes are not bonded to kerogen, but rather are present in the sediments as free hydrocarbons.     

茂名油页岩沉积有机质特征及古气候意义

基于海洋沉积确定的始新世晚期至渐新世早期(约33.5 Ma)的气候过渡期是新生代全球性气候事件,但长期以来相关的陆相沉积记录研究则比较缺乏。本文对形成于始新世晚期至渐新世早期的茂名油柑窝组油页岩样品进行了有机质丰度、烃类组成、单体烃碳同位素组成等分析,以期研究低纬度陆相沉积有机质对古近纪始新世-渐新世气候过渡期(EOT)的响应。研究结果显示,埋藏较浅的上部层位样品正构烷烃碳同位素组成显著正偏,为-19.1‰~-25.9‰,平均值为-22.2‰;而下部层位样品正构烷烃碳同位素组成在-23.7‰~-30.2‰,平均值为-26.3‰。两个样品正构烷烃碳同位素组成之差在1.5‰~8.1‰,平均值之差为4.6‰。正构烷烃碳同位素组成的显著差异指示了EOT低纬度陆相古气候变化引起的陆相有机质响应,而这种响应与当时大气CO2浓度和海洋温度降低导致的气候和植物群落变化密切相关,即可能存在着C3植物向C4植物的转化、C4植物的迅速增加并最终导致沉积有机质碳同位素组成的变化;也可能是由于大气CO2浓度降低导致的大气CO2碳同位素组成整体正偏的结果。很显然,进一步详细的连续剖面分析将对研究古近纪EOT低纬度陆相古气候变化提供重要科学依据。     

13C NMR measurements of the genetic potentials of oil shales

Cross polarization, magic-angle spinning ¹³C NMR measurements have been made on raw oil shales that represent a variety of geologic ages, origins, depositional environments and source locations. A high degree of correlation was established between the fraction of aliphatic carbon measured by ¹³C NMR, and the genetic potential, calculated from Fischer assay data. The correlation is independent of the type of kerogen in the raw shale, and its degree of evolution. A short discussion on the validity of various correlations between physical/chemical properties of oil shales and Fischer assay oil yields is given.     

The origin of the oil sand bitumens of Alberta: a chemical and a microbiological simulation study

An analytical method involving computerized gas Chromatographic mass spectrometric “Multiple Ion Cross Scan” technique has been developed for the study of chemical transformations in the biodegradation of crude oils.The technique has been employed in the study of the bitumens of the Alberta oil sands. Comparison of results from the in vitro simulation experiments with those from field samples of Alberta Lower Cretaceous oils and oil sands suggests that the Alberta oil sand bitumens have arisen from the biodegradation of conventional crude oils.     

Comparison of oil shales and kerogen concentrates by C nuclear magnetic resonance

Six oil shales and their kerogen concentrates have been studied using ¹³C CP/MAS NMR techniques to study the distribution of organic carbon species. It is found that if the aromatic and aliphatic regions are divided at about 80 or 100 ppm, the apparent aromaticities of a raw shale and its kerogen concentrate are in good agreement. The presence of oxygen-substituted carbons in the raw shales and their depletion in the kerogen concentrates are observed and discussed.