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1.
Surface sediments from the Outer Continental Shelf of Alaska were analyzed for hydrocarbons as part of an environmental survey sponsored by NOAA/BLM. Sediments were collected from the proposed oil lease areas of Beaufort Sea, southeastern Bering Sea, Norton Sound, Navarin Basin, Gulf of Alaska, Kodiak Shelf and lower Cook Inlet. Data on normal and branched alkanes and di- and triterpenoids from capillary gas chromatography (GC) and gas chromatography-mass spectrometry (GC/ MS) indicate that the area displays little evidence of petroleum hydrocarbons (i.e., seeps) except at a few isolated stations. Beaufort Sea sediments have the highest hydrocarbon budget, whereas Kodiak Shelf sediments have the lowest. The molecular markers of the hydrocarbons are of a mixed marine autochthonous and terrestrial allochthonous origin. Norton Sound and Cook Inlet sediments contain the highest levels of terrigenous lipids and Kodiak Shelf the lowest. The abundance of alkenes implies that relatively low oxidizing conditions exist in some of the depositional areas studied, suggesting that extraneous petroleum hydrocarbons introduced into these sediments would be expected to have a relatively long residence time. The distribution of polynuclear aromatic hydrocarbons (PAH) is complex and shows a pyrolytic origin. The data on perylene strongly favor the hypothesis that it is “performed” from terrigenous precursors and transported into the marine environment with no apparent in situ generation. Polynuclear aromatic hydrocarbons of diagenetic origin are probably dominant in Gulf of Alaska and Kodiak Shelf sediments.Two stations, north of Kalgin Island, in lower Cook Inlet and one in southeastern Bering Sea show typical weathered petroleum distribution of n-alkanes and triterpenoids. Probable pathways of transport and fate of petroleum hydrocarbons in case of an oil spill are also briefly discussed.  相似文献   

2.
A selection of Precambrian kerogens has been characterized by Curie-point pyrolysis combined with gas chromatography and gas chromatography-mass spectrometry. The resulting pyrograms can be classified into two groups. The first group of pyrograms is derived from kerogens whose pyrolysis products are dominated by alkanes, alkenes and alkadienes, whereas the second group contains pyrograms from kerogens that produce complex mixtures of branched hydrocarbons dominated by components at every third carbon number (C9, C12, C15, C18, C21, and up to C33). It is suggested that these branched hydrocarbons may remotely represent remains of isoprenoid hydrocarbons, or other branched hydrocarbons, of the original organisms.  相似文献   

3.
An alkane distribution in which isoprenoid alkanes are present in excess of n-paraffins and pristane, phytane, and norpristane (in this order) are the major components, has been found in two different beds of the Irati oil shale, Brazilian Permian formation of São Mateus do Sul, Paranã.  相似文献   

4.
In an attempt to evaulate the hypothesis that petroleum formation can be simulated using high temperatures, Green River Shale from Colorado, U.S.A., was subjected to closed-system pyrolysis for 16 hr at temperatures ranging from 300 to 500°C. Variations in the pyrolysis products (gases, volatile liquids, and organics extracts) over this temperature range duplicate the variations observed in many in situ studies of petroleum maturation.The sequence of products formed over this temperature range was used to define five different zones of maturation reactions: (1) a heterobond cracking zone; (2) a labile carbon bond cracking zone; (3) a free radical synthesis zone; (4) a wet gas formation zone; and (5) a dry gas formation zone. This high temperature simulation of maturation can be used to test other factors in petroleum formation such as mineral catalysis.  相似文献   

5.
Mathematical models have been developed which simulate both random and nonrandom thermal cracking of branched and straight-chain hydrocarbons. Application of these models to n-paraffins suggests that thermal cracking alone cannot be the dominant mechanism in formation of the n-paraffin distributions present in crude oils. Application to isoprenoid hydrocarbons indicates that nonrandom cracking could be important in producing the isoprenoid distributions found in oils.Results of the mathematical modeling show that methane formation should, as predicted from energy considerations, be kinetically disfavored. It therefore is likely that substantial quantities of methane are produced from saturated hydrocarbons only under thermal conditions more severe than those under which oil is produced.The mathematical models employed are adaptable for other geochemical applications, such as isotope fractionation.  相似文献   

6.
Spark-source mass spectrometric analysis of pyrolyzed Green River oil shale for trace element distribution showed enhanced concentrations for only lithium and beryllium. In general, trace elemental concentrations were found to be below anticipated crustal amounts. There appears to be no promise of any substantial accumulation of any trace elements within the organic matrix of Green River oil shale.  相似文献   

7.
高压-工频电加热原位裂解油页岩是吉林大学与俄罗斯托木斯克理工大学合作研究的具有占地面积小、污染小、工艺简单等优点的油页岩开采技术。先对油页岩使用高压电击穿,再使用电加热的二步法,可以达到快速裂解油页岩的效果。为了确定裂解油页岩的工艺参数,以及更好地掌握高压-工频电加热裂解油页岩技术,本文对油页岩在有、无氧气条件下的裂解过程进行了热分析试验。试验表明,在有氧与无氧加热条件下,都可完成油页岩的裂解,且裂解过程是相同的,都属于二段式裂解过程。氧在油页岩加热裂解时具有驱动作用,可以降低油页岩的裂解温度、节省能量、提高裂解速度。  相似文献   

8.
在野外地质考察、岩心观察和大量测试数据分析的基础上,对我国东北地区桦甸盆地始新统桦甸组和美国犹他盆地始新统绿河组油页岩中类异戊二烯烷烃、甾类和萜类等生物标志化合物特征进行了详细的对比研究,并探讨其对两地油页岩在有机质来源及古沉积环境上的差异指示意义。结果表明:在GC谱图上,桦甸油页岩Pr/Ph为1.47～2.03,具姥鲛烷优势;而绿河油页岩Pr/Ph为0.34～0.44,具植烷优势。GC-MS分析表明:桦甸油页岩规则甾烷C27-C28-C29呈反"L"型分布,∑(C27+C28)/∑C29为0.63～2.52;绿河油页岩规则甾烷C27-C28-C29呈钝角不对称"V"型分布,∑(C27+C28)/∑C29为0.96～1.20。桦甸油页岩萜类化合物中萜烯>ββ构型霍烷>αβ构型霍烷,以C29萜烯占优势;绿河油页岩中五环三萜烷>三环萜烷>四环萜烷,并检出丰富的γ-蜡烷和β-胡萝卜烷。两地油页岩生物标志化合物特征参数的对比分析揭示:桦甸油页岩为水生生物和高等植物双重生源,但细菌及藻类等水生生物的贡献较大,主要形成于弱还原淡水沉积环境;绿河油页岩有机质来源主要为细菌和藻类等水生生物,主要形成于强还原咸水沉积环境。  相似文献   

9.
Gas chromatographic analysis of the major isoprenoid carboxylic acids and the major ketone (6,10,14-trimethylpentadecan-2-one), derived from successive chromic acid oxidations of the kerogen of Green River Formation oil shale, indicates that their stereochemistry is compatible with the hypothesis that phytol or a derivative with the same carbon skeleton and stereochemistry was incorporated into the kerogen matrix.  相似文献   

10.
Hydrous and anhydrous closed-system pyrolysis experiments were conducted on a sample of Mahogany oil shale (Eocene Green River Formation) containing Type-I kerogen to determine whether the role of water had the same effect on petroleum generation as reported for Type-II kerogen in the Woodford Shale. The experiments were conducted at 330 and 350 °C for 72 h to determine the effects of water during kerogen decomposition to polar-rich bitumen and subsequent bitumen decomposition to hydrocarbon-rich oil. The results showed that the role of water was more significant in bitumen decomposition to oil at 350 °C than in kerogen decomposition to bitumen at 330 °C. At 350 °C, the hydrous experiment generated 29% more total hydrocarbon product and 33% more C15+ hydrocarbons than the anhydrous experiment. This is attributed to water dissolved in the bitumen serving as a source of hydrogen to enhance thermal cracking and facilitate the expulsion of immiscible oil. In the absence of water, cross linking is enhanced in the confines of the rock, resulting in formation of pyrobitumen and molecular hydrogen. These differences are also reflected in the color and texture of the recovered rock. Despite confining liquid-water pressure being 7-9 times greater in the hydrous experiments than the confining vapor pressure in the anhydrous experiments, recovered rock from the former had a lighter color and expansion fractures parallel to the bedding fabric of the rock. The absence of these open tensile fractures in the recovered rock from the anhydrous experiments indicates that water promotes net-volume increase reactions like thermal cracking over net-volume decrease reactions like cross linking, which results in pyrobitumen. The results indicate the role of water in hydrocarbon and petroleum formation from Type-I kerogen is significant, as reported for Type-II kerogen.  相似文献   

11.
黄骅坳陷齐家务地区的油源对比   总被引：5，自引：3，他引：2  
黄骅坳陷齐家务地区储油层主要为下第三系沙河街组沙一下段白云质灰岩。该区原油具有高密度、高粘度、高含硫量、中低凝固点、高初馏点和高胶质和沥青质含量等物理性质。在地球化学特征上,高碳数正构烷烃具有明显的奇偶优势,类异戊二稀烷烃具有植烷优势,甾烷组成具有明显的C27ααα甾烷优势,沙一段泥页岩的三环萜烷不发育、伽马蜡烷比较发育。这些地球化学特征表明该区原油为未熟-低熟油。分析原油和沙一段泥页岩的伽马蜡烷/C30藿烷与C29降藿烷/C30藿烷的关系以及伽马蜡烷/C30藿烷与Pr/Ph之间的关系,并结合地球化学特征,认为齐家务地区的烃源岩主要是沙一下段的泥页岩。  相似文献   

12.
通过密封金管-高压釜体系对珠江口盆地番禺低隆起-白云凹陷北坡恩平组炭质泥岩的干酪根(PY),在24.1 MPa压力、20℃/hr(373.5~526℃)和2℃/h(343~489.2℃)两个升温速率条件下进行热模拟生烃实验,分析气态烃(C1 5)和液态烃(C6 14和C14+)的产率,以及沥青质和残余有机质碳同位素组成。同时与Green River页岩(GR)和Woodford泥岩(WF)的干酪根,分别代表典型的I型和II型干酪根进行对比研究。结果显示PY热演化产物中总油气量明显低于GR和WF干酪根,且气态烃(C1 5)最高产率是液态烃的1.5倍,揭示恩平组炭质泥岩主要以形成气态烃为主。在热演化过程中,有机质成熟度和母质类型是控制油气比的主要因素,气态烃和轻烃的产率比值主要受热演化成熟度的影响。干酪根残余有机质碳同位素和沥青质碳同位素在热演化过程中受有机质成熟度的影响较小,δ13C残余和δ13C沥青质可以间接反映原始母质的特征,为高演化烃源岩油气生成提供依据。  相似文献   

13.
Two surface outcrop samples and three drill core samples of oil-impregnated sandstone from the P.R. Spring Seep, Uinta Basin, Utah were analyzed. These oils exhibit in common the entire homologous series of tricyclic diterpane hydrocarbons, which have been previously described only in extracts from the Mahogany Ledge Member of the Green River Formation. Hopane and a series of degraded hopanes are also present in the oil samples, while steranes are conspicuously absent. Aliphatic alkanes are present only in the deepest core sample.The cycloalkanes are apparently not readily utilized by the petroleum oxidizing microbes, and therefore survive the weathering process. Tricyclic and tetracyclic alkylated diterpanes are unchanged, whereas the series from norhopane through tetrakisnorhopane may be interpreted as progressive bacterial degradation of the hopane molecule.The occurrence and distribution of tricyclic diterpanes, of tetracyclic diterpanes and pentacyclic triterpanes is similar to the stratigraphically nearby Mahogany Ledge Member, suggesting that the oil shales were the source rocks for the oil now exposed as the P.R. Spring Seep. The absence of steranes, which are abundant in the oil shales, is puzzling.  相似文献   

14.
Stepwise pyrolysis-gas chromatography is used to examine and characterize the carbonaceous matter in sedimentary rocks. Low-temperature steps remove material normally volatile or extracted by benzene-methanol. Successively-higher temperature steps degrade the insoluble carbonaceous matter (kerogen) into smaller molecular pieces. The sequential pyrolysis steps have the advantage of breaking the kerogen at several temperatures which may be related to bond type or strength. The pyrolysis product chromatograms from each step can be compared. The molecular sizes (chain length) of kerogens fragments can be determined. The results presented here show the molecules in the range C11 to C23 because: (1) they can be compared to normal petroleum source rock extractables; and (2) these large molecules give a feeling for the molecular construction of the kerogen.Green River and Antrim shales show low-temperature material which is indigenous and not modified compared to the pyrolyzed kerogen fragments in the range C11C23. Kupferletten shows low-temperature material of a narrow molecular weight range of C15C19 which is probably derived from the kerogen. Monterey shale low-temperature material appears to be unrelated to the kerogen as represented by its pyrolysis products. The Pierre shale kerogen shows molecules over the range C11C23. Kerogen from the Romney shale has no molecules large than C8 in its pyrolysis products and no petroleum potential due to thermal and tectonic diagenesis.  相似文献   

15.
This study compares kinetic parameters determined by open-system pyrolysis and hydrous pyrolysis using aliquots of source rocks containing different kerogen types. Kinetic parameters derived from these two pyrolysis methods not only differ in the conditions employed and products generated, but also in the derivation of the kinetic parameters (i.e., isothermal linear regression and non-isothermal nonlinear regression). Results of this comparative study show that there is no correlation between kinetic parameters derived from hydrous pyrolysis and open-system pyrolysis. Hydrous-pyrolysis kinetic parameters determine narrow oil windows that occur over a wide range of temperatures and depths depending in part on the organic-sulfur content of the original kerogen. Conversely, open-system kinetic parameters determine broad oil windows that show no significant differences with kerogen types or their organic-sulfur contents. Comparisons of the kinetic parameters in a hypothetical thermal-burial history (2.5 °C/my) show open-system kinetic parameters significantly underestimate the extent and timing of oil generation for Type-IIS kerogen and significantly overestimate the extent and timing of petroleum formation for Type-I kerogen compared to hydrous pyrolysis kinetic parameters. These hypothetical differences determined by the kinetic parameters are supported by natural thermal-burial histories for the Naokelekan source rock (Type-IIS kerogen) in the Zagros basin of Iraq and for the Green River Formation (Type-I kerogen) in the Uinta basin of Utah. Differences in extent and timing of oil generation determined by open-system pyrolysis and hydrous pyrolysis can be attributed to the former not adequately simulating natural oil generation conditions, products, and mechanisms.  相似文献   

16.
Long-chain fatty acids (C10-C32), as well as C14-C21 isoprenoid acids (except for C18), have been identified in anhydrous and hydrous pyrolyses products of Green River kerogen (200–400°C, 2–1000 hr). These kerogen-released fatty acids are characterized by a strong even/odd predominance (CPI: 4.8-10.2) with a maximum at C16 followed by lesser amounts of C18 and C22 acids. This distribution is different from that of unbound and bound geolipids extracted from Green River shale. The unbound fatty acids show a weak even/odd predominance (CPI: 1.64) with a maximum at C14, and bound fatty acids display an even/odd predominance (CPI: 2.8) with maxima at C18 and C30. These results suggest that fatty acids were incorporated into kerogen during sedimentation and early diagenesis and were protected from microbial and chemical changes over geological periods of time. Total quantities of fatty acids produced during heating of the kerogen ranged from 0.71 to 3.2 mg/g kerogen. Highest concentrations were obtained when kerogen was heated with water for 100 hr at 300°C. Generally, their amounts did not decrease under hydrous conditions with increase in temperature or heating time, suggesting that significant decarboxylation did not occur under the pyrolysis conditions used, although hydrocarbons were extensively generated.  相似文献   

17.
Water samples from Narragansett Bay and the Providence River, and fulvic acid/ saline water solutions were examined for their ability to solubilize n-alkane (n-C16 and n-C20), isoprenoid (pristane) and aromatic (phenanthrene and anthracene) hydrocarbons and dibutyl phthalate. Removal of the dissolved organic matter (D.O.M.) from the natural samples by activated charcoal and by ultra-violet oxidation resulted in a 50–99 per cent decrease in the amounts of n-alkanes and isoprenoid hydrocarbons solubilized. This decrease was directly related to the amount of D.O.M. removed. The solubilities of the aromatic hydrocarbons were unaffected by the D.O.M. Fulvic acid from a marine sediment, surface active organic material isolated at a chloroform/sea water interface, organic material extracted from a marine sediment by sea water, and organic matter contributed by a municipal sewage effluent, promote n-alkane solubility when added to NaCl solutions and re-enhance solubility when added to organic depleted sea water. The solubility of No. 2 fuel oil increased 2.5 times in the presence of fulvic acid (3.7 mg C/l.) with most of the increase seen in the alkane and isoprenoid components.N-Alkane solubility increases in fulvic acid/saline water solutions with increasing pH and reaches a maximum with respect to ionic strength at I = 0.3. There is evidence to suggest that the mode of solubilization of the hydrocarbons is by incorporation into micelles formed by intermolecular association of the surface active humic-type monomers. The presence of ionic species is a prerequisite for micelle formation.  相似文献   

18.
The reactions of a terminal alkene (1-octadecene) and a polymethyl phenol (2,3,6-trimethylphenol) on activated carbon have been investigated in closed system pyrolysis experiments in the temperature range 170-340 °C. The reaction products of 1-octadecene included methane, isomeric octadecenes, methyl substituted alkanes, alkyl aromatics and an homologous series of n-alkanes with carbon numbers indicative of progressive single carbon depletion of the reactant. The reaction products of 2,3,6-trimethylphenol also contained methane, as well as C1-C4 methyl phenols produced by demethylation and methyl transfer reactions. A carbon surface reaction involving the formation of a reactive single carbon intermediate (i.e. methylene/carbene) is proposed. This reaction accounts for the products observed from the pyrolysis experiments and also is consistent with liquid hydrocarbon distributions found in petroleum basins. Methane was the dominant (ca. 85% of C1-C4) gaseous hydrocarbon product of 2,3,6-trimethylphenol but accounted for only ca. 17% of the C1-C4 hydrocarbons from 1-octadecene. These findings suggest that single carbon surface reactions may play an important role in the geochemical formation of crude oil and natural gas and that the composition of the source material and therefore the type of organic compounds undergoing such reactions, influences the hydrocarbon gas composition in sedimentary basins.  相似文献   

19.
Organic geochemical evaluation of thirty-two Aptian to Campanian shale samples from seven wells drilled on the shelf of the Orange Basin (southwestern Atlantic margin) was carried out in order to determine their origin, depositional environment, thermal maturity and hydrocarbon potential. The shale samples, selected to represent highstand, lowstand and transgressive systems tracts, were analysed by Rock–Eval pyrolysis for total organic C characteristics and by gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS) for n-alkanes, aliphatic isoprenoid hydrocarbons and biomarkers (steranes, hopanes and tricylic terpanes). For most of the shale samples Rock–Eval data, hydrogen (HI) and oxygen index (OI) point to mainly Type III terrigenous organic matter. Only a few samples of Turonian age reveal a higher proportion of marine organic matter being classified as Type II/III or Type II. Biomarker parameters suggest that the samples are deposited under suboxic to oxic environmental conditions. Rock–Eval data and biomarker maturity parameters assign for most of the samples a maturity level at the beginning of the oil window with some more mature samples of Aptian, Albian and Cenomanian age. The hydrocarbon generation potential is low for most of the shelf shales as indicated by the S2/S3 ratio and HI values. Exceptions are some samples of Turonian and Aptian age.  相似文献   

20.
胜利河油页岩位于青藏高原腹地的羌塘盆地,具单层厚度薄、区域延伸长的特点,为羌塘盆地新发现的又一处海相油页岩.采用GC-MS(IRMS)分析方法对该油页岩进行了研究,结果表明,胜利河油页岩(11层以及13层)含有丰富的正烷烃、类异戊二烯烃、萜类化合物和甾类化合物.正构烷烃呈前高后低的单峰型分布,nC15、nC16为主峰碳,轻烃组分占有绝对优势,OEP值0.96～0.97,接近平衡值1.00,Pr/Ph为0.57～0.75,显示弱的植烷优势;萜烷丰度顺序为五环三萜烷》三环萜烷》四环萜烷;规则甾烷呈不对称的"V"字型分布,表现为C27》C29》C28的分布特征.这些特征与剖面中其他岩性的生物标志物特征存在一定的差异,9层泥晶灰岩C21-/C21 值为0.86,轻烃优势并不明显;14层泥灰岩C21-/C21 值为0.41,具有明显的重碳优势;9层泥晶灰岩以及12层泥灰岩规则甾烷呈C29》C27》C28的特征也与油页岩层存在显著的差异.这些差异不仅反映了油页岩层与其他岩性间生物母源输入的差异,也反映了他们之间沉积环境的不同.胜利河地区油页岩的形成是综合因素控制的结果,古地理变化、海平面升降、生物群差异以及气候的变化均对该区油页岩的形成有一定的影响.  相似文献   

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