共查询到20条相似文献，搜索用时 15 毫秒
1.
利用色谱—质谱定量分析技术,对40余个取自四川盆地北部石龙场和元坝地区不同成熟度的中、下侏罗统湖相烃源岩和原油样品进行分析,以此揭示其重排藿烷组成和分布的变化特征,并进行精细的油源对比。研究结果表明,不同成熟度的烃源岩中重排藿烷的丰度相差悬殊。石龙场地区Ro值为0.8%~1.0%的中侏罗统千佛崖组和下侏罗统自流井组大安寨段泥岩中,各类重排藿烷异常丰富,检出了17α（H）-重排藿烷、18α（H）-新藿烷和早洗脱重排藿烷3个完整碳数系列。它们的相对含量大都数倍于规则藿烷,是该层系烃源识别的分子标志。而在相邻的元坝地区相带、岩性相近的这两层段高成熟（Ro值主要在1.4%~1.9%）烃源岩中,藿烷类化合物出现异常变化,重排藿烷的相对含量很低,可能与干酪根在高热演化阶段生成的规则藿烷比例较高有关。烃源岩中高丰度重排藿烷并不取决于其绝对含量的高低,而在于它们相对于规则藿烷的富集。弱氧化的沉积环境是导致重排藿烷相对富集的一个重要原因,而有机质生源中的细菌组成可能更是一个关键因素。当烃源岩达到高成熟阶段时,藿烷类化合物的组成和分布不再受控于热化学动力学机制,各类重排藿烷均按一定比例分布,基本失去了其地球化学属性。区内中、下侏罗统原油中重排藿烷的组成和分布也随热演化程度而变化。它们在成熟原油中极丰富,而在高成熟原油中则很少,与烃源岩存在对应关系。经油—岩对比,认为这些原油来源于所在层位的烃源岩。 相似文献
2.
Chicarelli MI Hayes JM Popp BN Eckardt CB Maxwell JR 《Geochimica et cosmochimica acta》1993,57(6):1307-1311
The carbon and nitrogen isotopic compositions of seven of the most abundant alkylporphyrins from the Serpiano oil shale (marine, Triassic) were determined. For the C31 and C32 butanoporphyrins, values of delta 13CPDB and delta 15NAIR averaged -24.0% and -3.1%. In contrast, the C31 and C32 methylpropanoporphyrins, DPEP, and a C30 13-nor etioporphyrin had delta 13C and delta 15N values averaging -27.5 and -3.3%, respectively. Carbon and nitrogen isotopic values for kerogen averaged -30.8 and -0.9, whereas those for total extract averaged -31.6, and -4.0%. The butanoporphyrins apparently derive from a biological source different from that giving rise to the other porphyrins, their 13C enrichment not being related to carbon isotopic fractionation accompanying diagenetic reactions. The delta 15N values for all the porphyrins indicate that the depletion of 15N observed in the kerogen is of primary origin. Consistent with the very high abundance of hopanoids and methyl hopanoids in the aliphatic hydrocarbon fraction, it is suggested that cyanobacterial fixation of N2 may have been the main cause of 15N depletion. 相似文献
3.
Paul Farrimond Andrew N Bishop Helen E Innes Colin E Snape 《Geochimica et cosmochimica acta》2003,67(7):1383-1394
Hopanoids bound into the insoluble organic matter (kerogen) of Recent sediments from a freshwater lake (Priest Pot) and an anoxic sulphidic fjord (Framvaren) were released by hydropyrolysis and examined by gas chromatography-mass spectrometry. Bound hopanoids are present in high concentration (190-1400 μg/g TOC) and represent 22 to 86% of the total analysable hopanoids (i.e., bound and solvent-soluble), this proportion increasing with depth in Framvaren Fjord. The hopanes generated by hydropyrolysis contain higher amounts of the C35, C32, and C30 homologues, reflecting the carbon number distribution of the bound hopanoids and indicating that both biohopanoids (C30 and C35) and their diagenetic products (dominated by C32) are incorporated into the kerogen on a timescale of only 0 to 350 years. Sequential (multiple temperature) hydropyrolysis experiments gave an indication of the relative strengths of bonds being cleaved in association with hopane generation: The hopanoids of a sediment from Priest Pot are almost entirely bound by strong covalent bonds, interpreted to be mainly ether linkages, whilst a Framvaren sediment contains hopanoids that are bound by a mixture of weak di-/polysulphide linkages and stronger ether bonds. Labelling with deuterium indicated that the strong covalent linkages dominate, even for the Framvaren sediment. 相似文献
4.
利用芳烃参数研究煤系烃源岩中重排藿烷成因 总被引：4，自引：1，他引：3
研究发现鄂尔多斯盆地部分地区上古生界煤系烃源岩存在较高丰度的17α(H)-重排藿烷和早洗脱重排藿烷,在对重排藿烷分布、组成特征及生标组成特征研究的基础上,应用芳烃参数对高丰度重排藿烷的成因进行了探讨。饱和烃生物标志物组成特征显示,高重排藿烷与陆源高等植物生源关系密切,主要在弱氧化沉积环境下演化形成。具有高-异常高丰度17α(H)-重排藿烷和早洗脱重排藿烷(C30*/C30H>0.2、C30E/C30H>0.1)的烃源岩二环+三环芳烃相对含量一般大于50%,四环、五环芳烃含量相对较低,普遍低于35%,未见芳香甾萜类,研究认为其生源主要为陆生高等植物;甲基菲指数MPI1、MPI2和甲基菲比值F1研究结果显示,Pr/Ph>1的弱氧化环境烃源岩17α(H)-重排藿烷和早洗脱重排藿烷在进入成熟阶段后开始大量形成,并随成熟度升高而增大;Pr/Ph<1还原环境下的烃源岩重排藿烷丰度相对较低,但在进入成熟阶段后仍有随成熟度升高而增大的趋势;三芴系列化合物参数表明,沉积环境的弱氧化性质对17α(H)-重排藿烷和早洗脱重排藿烷的形成有较大的影响,沼泽相沉积环境最有利于重排藿烷的形成。 相似文献
5.
通过对TZ62井原油进行热模拟实验,探讨热演化程度对原油中重排藿烷类化合物形成分布的影响及其地球化学意义。实验发现：在400～500 ℃阶段,随着热演化程度的增加,原油中高碳数微晶蜡类长链化合物热裂解和原油中的沥青质热降解作用对重排藿烷的形成具有贡献作用。在500～550 ℃对应的原油裂解高峰阶段,藿烷类化合物浓度明显降低,且17α(H)-藿烷比重排藿烷类化合物具有更快的热裂解速率。在温度为550～600 ℃阶段,较高的热演化程度对17α(H)-藿烷甲基重排作用形成重排藿烷具有贡献作用。重排藿烷参数(17α(H)-重排藿烷/17α(H)-藿烷、Ts/Tm)在400～500 ℃变化较弱,几乎不受热演化程度的影响;在500～550 ℃的原油裂解高峰阶段,逐渐增大;在550～600 ℃发生反转,逐渐减小。重排藿烷参数可作为高成熟阶段原油成熟度判识的有效参数,其有效应用范围是生油窗晚期至原油裂解高峰期。 相似文献
6.
现代沼泽沉积物中五环三萜类的组成特征 总被引：5，自引：1，他引：5
本文所研究样品采自甘南寒冷潮湿区沼泽。对其烷烃馏分进行GC-MS分析后,检测出五个新的脱A-羽扇烯和二烯,通过质谱分析,初步确定了它们的烯键位置,并探讨了脱A-羽扇烯形成的可能途径。检测出的类化合物包括C27、C30和C31烯以及C27、C29-C32烷。 根据类化合物的分布,提出了C29烷可能主要来自陆源物。高碳数的类化合物可能主要来自细菌和水生生物。烷构型组成以ββ型为主;烯占较高的比例,这些都反映了早期成岩阶段的特征。有意义的是样品中均含D环芳构化8,14-断烷。 相似文献
7.
对北京地区具代表性的环境功能区土壤剖面中的藿烷、甾烷、芳香甾烷类分子标志物含量及组成变化进行了分析。在10个土壤剖面中都检测到了不同浓度的藿烷与甾烷系列化合物,其中水稻田（B9）和城区绿地（B7）这些化合物的含量最高,在农田（B6、B9）和城区绿地（B7）表层土壤中还检测到了少量的三芳甾烷。土壤剖面中藿烷和甾烷含量随深度的增大而降低,在表层30 cm深度范围内的变化较大,30 cm以下其含量波动甚微,但不同深度土层中藿烷和甾烷化合物的指纹特征相近。表明表层土壤均不同程度受到了化石燃料及其衍生物的影响,并且土壤剖面不同深度土壤中藿烷和甾烷具有相关性,受石油类燃烧污染源的影响较大,煤燃烧污染影响的比重相对较小,而且深部土壤的藿烷与甾烷主要来源于表层土壤。 相似文献
8.
In addition to the previously reported 25-norhopanes and 25-norhopanoic acids, for the first time we report the identification of 25-norbenzohopanes. The hydrocarbon composition of the bitumen from Palaeozoic carbonates in northern Alberta displays molecular evidence for severe levels of biodegradation characterised by the removal of C30–C35 hopanes. Biodegradation is also indicated by the removal of C32 and C33 benzohopanes. The appearance of C31 and C32 25-norbenzohopanes corresponds to the decrease in C32 and C33 benzohopanes, suggesting that 25-norbenzohopanes originate by demethylation of benzohopane counterparts. Demethylation at C-10 in the hopanoids affects a broader class of compounds that so far includes the hopanes and hopanoic acids, as well as the benzylated hopanoid species. 相似文献
9.
The lipid biomarkers of hopanoids in cold seep carbonates from the South China Sea continental slope were investigated by gas chromatography–mass spectrometer (GC–MS) and gas chromatography-isotope ratio-mass spectrometer (GC-ir-MS). The distribution of hopanes/hopenes shows a preference for the ‘biological’ 17β(H), 21β(H)-over the ‘geological’ 17α(H), 21β(H)-configuration. This interpretation is in agreement with the strong odd–even preference of long-chain n-alkanes in those samples, suggesting that the ββ hopanes may be the early diagenetic products of biohopanoids and the αβ, βα configurations of hopanes were mainly derived from allochthonous sources contributing to the organic matter of the carbonates. In terms of hopanoid acids, the C30 to C33 17β(H), 21β(H)-hopanoid acids were detected with C32 17β(H), 21β(H)-hopanoid acid being the most abundant. However, there is a significant difference in stable carbon isotopic compostions of the C32 17β(H), 21β(H)-hopanoic acid among samples (−30.7‰ to −69.8‰). The δ13C values match well with the carbon isotopic compositions of SRB-derived iso-/anteiso-C15:0 fatty acids in the samples, which strongly depend on the carbon utilization types by microbe. The most abundant compound of hopanols detected in the samples, C30-17β(H), 21β(H)-hopanol, may be a good indicator of diagenetic product of type I methanotrophs. The molecular and carbon isotopic compositions of hopanoids demonstrate clearly that there is a combination contribution of both SRB and type I or type X methanotrophs to the source organism in the seep carbonates from the South China Sea continental slope. 相似文献
10.
Methylhopanoids are organic compounds synthesized by certain bacteria, that when preserved in sediments act as molecular fossils or biomarkers for organic matter inputs from specific bacterial sources. Two series of methylhopanoids occur, each mainly deriving from a distinct bacterial source: cyanobacteria (2-methyl) and methanotrophic bacteria (3-methyl). The abundance and composition of methylhopanoids within sediments of modern depositional environments varies widely, apparently due to different bacterial communities contributing to the sedimentary organic matter. Comparable molecular characteristics are found in oils and their source rocks. Consequently, methylhopanoids are valuable in oil-oil and oil-source rock correlations, distinguishing between samples related to different depositional environments. In particular, abundant 3β-methylhopanoids (from methanotrophic bacteria or an additional unknown bacterial source) are characteristic of some modern alkaline saline lake environments. Comparable compositional features in the methylhopanes of oils allow the assignment of lacustrine oils offshore West Africa to two distinct lacustrine source rock facies, and to distinguish between different marine source facies, thus refining oil-source rock correlation. 相似文献
11.
Ze Zhang Canfa Wang Xuan Qiu Xianyu Huang Shucheng Xie 《Frontiers of Earth Science》2009,3(3):320-326
Based on gas chromatography and gas chromatography-mass spectrometry analyses, an amazing amount of hopanoids was detected
in the peat deposits in the Dajiuhu National Wetland Park in central China. The hopanoids identified included hopanes (C27-C31 αβ, C27-C32 ββ, C29 βα), hopenes (hop-22(29)-ene, 22,29,30-trinorhop-17(21)-ene, hop-17(21)-ene, hop-13(18)-ene, etc.), hopanoic acids (C31-C34 ββ, C32-C33 βα, C32 αβ), hopanols (C32 ββ and αβ) and hopanone (22,29,30-trinorhop-21-one). C31 αβ-22R hopane was found to be the dominant hopanoid, more abundant than individual nalkanes derived from higher plants. These
hopanoids, exclusive of some hopenes, are proposed to be primarily from bacteria. The dominant C31 αβ-22R hopane in young sediments, without any thermal maturation, might be formed through microbial epimerization under acidic
conditions in the peatland as suggested before, or directly from aerobic bacteria. This finding highlights the importance
of microbes in the formation of peatland as well as in the reconstruction of paleoenvironments. 相似文献
12.
Yangming Zhu 《中国地球化学学报》2001,20(1):73-87
Based on the compositions and distributions of biomarkers in thirty-five representative oil samples, oils from the Tarim Basin of northwestern China are mainly divided into two oil families. One oil family contains relatively low amounts of C15-C20 isoprenoid hydrocarbons and shows pristane predominance with Pr/Ph ratios ranging from 1.50 to 3.00. The GC/MS analytical data of these oils show the occurrence of abundant hopanes, and low concentrations of steranes and tricyclic terpanes with hopanes/steranes ratios from 6.25 to 12.24 and tricyclic terpanes/hopanes ratios from 0.03 to 0.24. These oils contain low drimane relative to homodrimane (C15/C16 < 1.0) and abundant rearranged bicyclanes in bicyclic sesquiterpanes. They are dominated by low carbon number (C19-C21) compounds in the tricyclic terpanes, and are rich in rearranged hopanes, C29Ts and an unknown C30 compound in pentacyclic triterpanes. These geochemical characteristics suggest that the oils were generated mainly from terrigenous organic matter. The other oil family shows remarkably different biomarker compositions and distributions. The oils revealed Pr/Ph ratios of about 1.0, high drimane/homodrimane ratios (>1.0), low hopanes/steranes ratios (0.65–2.50), high tricyclic terpanes/hopanes ratios (0.30–2.00) and a dominant peak at C23 in tricyclic tepanes, suggesting a marine organic origin. Oil-source rock correlation indicates that these two oil families seem to have been derived from Mesozoic Jurassic-Triassic terrestrial source rocks (shales and coal seams) and Lower Paleozoic Ordovician-Cambrian marine source rocks, respectively. 相似文献
13.
Crude oil samples from two basins were analyzed using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC–TOFMS) to better understand the compositional heterogeneity of branched-cyclic hydrocarbons. GC×GC–TOFMS and conventional GC–MS results were compared. GC×GC–TOFMS revealed a wide range of compounds, including tricyclic, tetracyclic and pentacyclic terpane series, rearranged hopanes, methyl hopanes, secohopanes, onoceranes and steranes. Assignment of methyl hopane and 8,14-secohopane series other than onocerane isomers was only possible due to the high peak capacity and sensitivity of GC×GC. The oils comprised a mixture of two end members: non-biodegraded oil with abundant tricyclic terpanes and hopanes, and severely biodegraded oil with abundant 8,14-secohopane and demethylated tricyclic terpanes. A predominance of two distinct series, 3β-methylhopane and onocerane, was detected only in the lacustrine samples (classification based on biomarker parameters). In contrast, the predominance of a 2α-methylhopane series and lack of onocerane were found only for the marine oil sample. The results suggest that the distribution of 3β- and 2α-methylhopane series and the presence or absence of onocerane isomers reflect genetic differences in the source organic matter and that these compounds are new classes of biomarkers that can used as depositional paleoenvironment proxies. 相似文献
14.
A geochemical investigation of oils in sandstone core plugs and drill stem test oils was carried out on samples from a North Sea reservoir. A sample of diesel used as a constituent of the drilling fluids was also analysed. The aliphatic and aromatic hydrocarbons and polar non-hydrocarbons were isolated using solid phase extraction methods. GC analysis of the hydrocarbon fraction of the core extract indicated that contamination may be diesel derived. From analysis of diesel some compound classes are less likely to be affected by contamination from diesel itself including: steranes, hopanes, aromatic steroid hydrocarbons, benzocarbazoles and C0–C3-alkylphenols. 相似文献
15.
1 Introduction As a linkage between the biosphere and the geosphere, organic geochemistry, especially molecular markers, has become a powerful tool for investigating important geological events and the evolutionary history of ancient life on Earth (Kvenvo… 相似文献
16.
《Applied Geochemistry》2006,21(6):964-976
Hopanoids have been widely used as characteristic biomarkers to study inputs of bacterial biomass to sediments because they are preserved in the geologic record. A limited number of studies have been performed on hopanoid biomarkers in soils. The present study examined the distribution and potential preservation of hopanoids in soils that are developed under different climatic conditions and varying vegetative inputs. Solvent extraction and sequential chemical degradation methods were employed to extract both “free” and “bound” hopanoids, from three grassland soils, a grassland–forest transition soil, and a forest soil from Western Canada. Identification and quantification of hopanoids in the soil samples were carried out by gas chromatography–mass spectrometry. Methylbishomohopanol, bishomohopanol and bishomohopanoic acid were detected in all solvent extracts. The base hydrolysis and ruthenium tetroxide extracts contained only bishomohopanoic acid at a concentration range of 0.8–8.8 μg/gC and 2.2–28.3 μg/gC, respectively. The acid hydrolysis procedure did not release detectable amounts of hopanoids. The solvent extraction yielded the greatest amounts of “free” hopanoids in two of the grassland soils (Dark Brown and Black Chernozems) and in the forest soil (Gray Luvisol). In contrast, the chemical degradation methods resulted in higher amounts of “bound” hopanoids in the third grassland soil (Brown Chernozem) and the transition soil (Dark Gray Chernozem), indicating that more hopanoids exist in the “bound” form in these soils. Overall, the forest and the transition soils contained more hopanoids than the grassland soils. This is hypothesized to be due to the greater degradation of hopanoids in the grassland soils and or sorption to clay minerals, as compared to the forest and transition soils. 相似文献
17.
Gel permeation chromatography (GPC) using a high performance liquid chromatography (HPLC) system was studied for the separation and enrichment of steroid and hopanoid hydrocarbons from crude oil for stable carbon isotope analysis. A crude oil sample was pretreated using silica gel chromatography and 5A molecular sieve to remove polycyclic aromatic hydrocarbons and n-alkanes. The GPC behavior of both the pretreated saturated hydrocarbon fraction of the oil and standard steroid [5α(H), 14α(H), 17α(H) C27–C29 steranes], hopanoid [17α(H) C27 trisnorhopane, 17α(H), 21β(H) C29–C32 hopanes] and triterpenoid [18α(H)-oleanane, gammacerane] mixtures were examined. The results indicate that 17α(H), 21β(H) hopanes as well as steranes could be enriched efficiently using GPC and that they could be obtained without removing n-alkanes from the oil saturated hydrocarbon fraction. The GPC behavior of steroid and triterpenoid hydrocarbons was controlled by molecular size and shape. 相似文献
18.
Hopanoids are triterpenoids produced mainly by bacteria, are ubiquitous in the environment, and have many important applications as biological markers. A wide variety of related hopanoid structures exists, many of which are polyfunctionalized. These modifications render the hopanoids too involatile for conventional gas chromatography (GC) separation, so require either laborious oxidative cleavage of the functional groups or specialized high temperature (HT) columns. Here we describe the systematic evaluation and optimization of a HT–GC method for the analysis of polyfunctionalized hopanoids and their methylated homologs. Total lipid extracts are derivatized with acetic anhydride and no further treatment or workup is required. We show that acid or base hydrolysis to remove di- and triacylglycerides leads to degradation of several BHP structures. DB-XLB type columns can elute hopanoids up to bacteriohopanetetrol at 350 °C, with baseline separation of all 2-methyl/desmethyl homologs. DB-5HT type columns can additionally elute bacteriohopaneaminotriol and bacteriohopaneaminotetrol, but do not fully separate 2-methyl/desmethyl homologs. The method gave 2- to 7-fold higher recovery of hopanoids than oxidative cleavage and can provide accurate quantification of all analytes including 2-methyl hopanoids. By comparing data from mass spectra with those from a flame ionization detector, we show that the mass spectromet (MS) response factors for different hopanoids using either total ion counts or m/z 191 vary substantially. Similarly, 2-methyl ratios estimated from selected-ion data are lower than those from FID by 10–30% for most hopanoids, but higher by ca. 10% for bacteriohopanetetrol. Mass spectra for a broad suite of hopanoids, including 2-methyl homologs, from Rhodopseudomonas palustris are presented, together with the tentative assignment of several new hopanoid degradation products. 相似文献
19.
A suite of reservoir cores (oil sands) from a single well in Bohai Bay Basin, East China, displayed a progressive increase in petroleum biodegradation extent on the basis of bulk composition and 25-norhopane content. This fits with the proposal that subsurface petroleum biodegradation is dominantly an anaerobic process and usually occurs at the oil–water contact. It is likely that sequential microbial degradation of hydrocarbons under anoxic conditions does not occur in a true stepwise fashion, but is controlled by various factors such as concentration and solubility of hydrocarbons and their diffusion rate to the oil/water contact. In fact, 25-norhopanes were formed prior to the complete elimination of the acyclic, and mono- and bicyclic alkanes. An inverse response of the 22S/(22S + 22R) ratio between each extended 17α(H)-hopane and its corresponding 25-norhopane was observed as severe biodegradation occurred, supporting the proposal that the 25-norhopanes originate from demethylation of hopanes. Field observation revealed that biomarkers without extended alkyl side chains, such as oleanane, gammacerane and β-carotane, have significant resistance to biodegradation and can be used as naturally occurring “internal standards” to evaluate variations in other biomarkers. The results suggest that the quantity of 25-norhopanes showed a minor increase as the hopanes decreased significantly, i.e. only partial hopane conversion to the corresponding 25-norhopanes. Alternative degradation pathways for hopanes might occur in reservoirs, in addition to C-25 demethylation. 相似文献
20.
鄂尔多斯盆地东北部上古生界煤系烃源岩17α(H)-重排藿烷类的分布及成因探讨 总被引：3，自引：0，他引：3
鄂尔多斯盆地东北部上古生界10个典型煤系烃源岩样品中检测出三类重排藿烷,分别为17α(H)-重排藿烷、18α(H)-新藿烷以及未知结构的早洗脱重排藿烷。烃源岩样品中藿烷类具有两种分布型式:①以C30藿烷为主峰的C27~C35(缺C28)藿烷类常规分布型式,含少量17α (H)-重排藿烷和18α(H)-新藿烷;②以富含17α(H)-重排藿烷和C30早洗脱重排藿烷为特征。含有高~异常高相对丰度17α(H)-重排藿烷的烃源岩样品,其17α(H)-重排藿烷的绝对浓度也明显较高。从烃源岩生源构成、有机质丰度及其赋存状态、成熟度以及沉积与成岩环境4个方面探讨了高丰度17α(H)-重排藿烷的成因。研究结果表明,烃源岩中高丰度的17α(H)-重排藿烷的形成与高等植物生源有一定联系、亚氧化-氧化的扇缘泥炭沼泽相是形成高~异常高丰度17α(H)-重排藿烷的有利沉积相带;而烃源岩显微组分、有机质丰度及其赋存状态以及有机质成熟度的影响尚不确定。 相似文献