Analysis and occurrence of C26-steranes in petroleum and source rocks

Moldowan, J. Michael; Lee, Cathy Y.; Watt, David S.; Jeganathan, Alwarsamy; Slougui, Nacer-Eddine; Gallegos, Emilio J.

doi:10.1016/0016-7037(91)90164-z

Cited by 84 publications

(27 citation statements)

References 35 publications

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“…Thus, from a viewpoint of methyl moieties, an origin from a prokaryotic methylotroph can be used to explain the detected 4-methyl (C 22-23 , C 27-30 ), 4,4-dimethyl steranes (C 22-24 , C 28-30 ) and lanostanes (C 24-25 , C 30 , with 4,4,14-trimethyl moieties) in this study. The C 26 -norcholestanes in our samples most likely originated by bacterially mediated alteration of C 27 sterols, as suggested by Moldowan et al (1991). Low molecular weight C 21 -C 25 steranes and C 22 ÀC 26 methyl steranes were reported in saturated hydrocarbon fractions derived from fermentation of immature organic matter (Ding et al, 2001), which also indicates a bacterial source for the unusual short chain steranes (C 20 -C 26 ) in this study.…”

Section: Discussionsupporting

confidence: 49%

“…However, there appear to be more reports of the occurrence of lanosterol in marine and freshwater sponges or other non-photosynthetic organisms (Chaffee et al, 1986). Thus, we consider that the C 24 and C 25 lanostanes in our samples were derived mainly from sponges and/or dinoflagellates, as indicated by the following: (1) In our literature survey (Van Graas et al, 1982;Wolff et al, 1986;Summons et al, 1987;Chen et al, 1989;Moldowan et al, 1991;Volkman et al, 1993;Peters et al, 2005), all reports of long chain steranes (A-nor-steranes, norcholestanes, 4-methyl steranes and lanostanes) and pregnanes refer to a sponge and/or a dinoflagellate source; (2) lanosterol and cycloartenol in some sponges are both transformed to 4,4,14-trimethyl sterols (Kerr et al, 1989), the basic skeleton of lanostanes; (3) although some sponges are incapable of de novo biosynthesis, they can also selectively modify the molecular nucleus to give rise to unique A-nor or 19-nor skeletons (Kerr et al, 1989), hydrocarbon equivalents of which are described as androstane, which is present in our two oil samples; (4) short chain sterols have been more frequently identified in gorgonians and sponges than in dinoflagellates . For example, short side chain sterols of the androstane and pregnane type, and of the 3-hydroxy-pregnan-20-type, were found in sponges (H. flavescens) from the Black Sea (Elenkov et al, 1999); (5) an unusually large number of C 21 and C 22 short chain steranes, counterparts of short chain sterols, and much more abundant in sponges , are distinctly dominant in our samples.…”

Section: Discussionmentioning

confidence: 99%

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Identification of C24 and C25 lanostanes in Tertiary sulfur rich crude oils from the Jinxian Sag, Bohai Bay Basin, Northern China

Lü

Sheng

Peng

et al. 2011

Organic Geochemistry

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Section: Discussionsupporting

confidence: 49%

Section: Discussionmentioning

confidence: 99%

Identification of C24 and C25 lanostanes in Tertiary sulfur rich crude oils from the Jinxian Sag, Bohai Bay Basin, Northern China

Lü

Sheng

Peng

et al. 2011

Organic Geochemistry

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“…7: 29Ts/(29Ts + norhopane) (Moldowan et al, 1991); 8: 22S/(22S+22R) of C31 αβ-hopanes (Mackenzie et al, 1980); 9: ββ/(ββ + αα) of C29 (20R+20S) sterane isomers (Mackenzie et al, 1980); 10: 20S/(20S+20R) of C29 sterane isomers (Mackenzie, 1984); 11: diasteranes/(diasteranes + regular steranes) (Peters et al, 2005); 12: C20/(C20+C28) triaromatic steroids (TAS) (Mackenzie et al, 1985); 13: C28TA/(C28TA+C29MA) (Mackenzie et al, 1985); 14: 20: MA(I)/MA(I + II) (Peters et al, 2005); 15: Methyl-phenanthrene ratio (MPR) (Radke et al, 1982b); 16: Methyl phenanthrene index 1 (MPI1) (Radke et al, 1982a); 17: MDR (Radke et al, 1986); 18: Methyl phenanthrene distribution fraction (MPDF) (Kvalheim et al, 1987). …”

Section: Discussionmentioning

confidence: 99%

“…The C 31 αβ -hopane 22S/(22S + 22R) ratio values of 0.51-0.64 (Table 3, column 8) suggest that almost all samples are fully isomerised, but this ratio has limited application to maturities beyond the early oil window (Peters et al, 2005). The norneohopane (29Ts) and norhopane (29αβ) ratio 29Ts/(29Ts + 29ab) (Moldowan et al, 1991) varies between 0.19 and 0.59 (Table 3, column 7;Figs. 3,4), showing a relatively wide range as has also been observed on the Norwegian Continental Shelf (cf.…”

Section: Saturated Hydrocarbon Maturity Parametersmentioning

confidence: 97%

Organic Geochemistry of Barents Sea Petroleum: Thermal Maturity and Alteration and Mixing Processes in Oils and Condensates

Lerch

Karlsen

Matapour

et al. 2016

Journal of Petroleum Geology

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The petroleum system in the Barents Sea is complex with numerous source rocks and multiple uplift events resulting in the remigration and mixing of petroleum. In order to investigate the degree of mixing, 50 oil and condensate samples from 30 wells in the SW Barents Sea were geochemically analysed by GC-FID and GC-MS to INTRODUCTIONRecent oil discoveries in the Barents Sea, such as Gotha, Alta, Wisting, Johan Castberg (Skrugard and Havis), Nucula and Goliat ( Fig. 1) (Norwegian Petroleum Directorate, 2014), are evidence for the presence of commercial volumes of liquid petroleum in an area which was long considered to be gas-prone (Stewart et al., 1995). These discoveries led to renewed geochemistry-based investigations of the petroleum systems in the Barents Sea (Bjorøy et al., 2009;Killops et al., 2014;Rodrigues-Duran et al., 2013). The presence of multiple potential source rocks may have resulted in the occurrence of mixed petroleum charges (Ohm et al., 2008;Vobes, 1998). Petroleum distribution and composition was influenced by several episodes of Cenozoic uplift and burial (Cavanagh et al., 2006;Ohm et al., 2008). Cenozoic uplift had a negative effect on the petroleum systems because it resulted in the cessation of hydrocarbon generation and expulsion (Henriksen et al., 2011). In addition, uplift resulted in alterations to the physical properties of trapped hydrocarbons, including changes to gas-to-oil ratios and associated expansion of gas columns, causing oil to be forced out of structures below the spill point (Nyland et al., 1992). Remigration/leakage of petroleum phases also occurred as a result of cap-rock failure or fault reactivation (Ohm et al., 2008;Ostanin et al., 2013). Thus geochemical interpretations in the Barents Sea suggest that uplift-related remigration/long-distance migration may be the key to understanding the complex petroleum systems present (Lerch et al., 2016;Ohm et al., 2008;Rodrigues-Duran et al., 2013).While Rodrigues Duran et al. (2013) focused mainly on the gaseous and light hydrocarbon maturation and alteration parameters in samples from the Hammerfest Basin, Ohm et al. (2008) among others investigated isotope signatures of oils from a larger area to identify potential source rocks. Bjorøy et al. (2009) correlated source rock extracts with oils to determine genetic relationships, and Killops et al. (2014) used novel age-related biomarkers to identify possible source rocks. However, until now few studies have attempted to correlate maturity signatures in order to understand regional variations in petroleum composition.The purpose of this study is to investigate the molecular evidence for the presence of mixed or transformed (biodegraded or water-washed) petroleum in the Barents Sea, and to assess regional similarities and/or differences in petroleum. Saturated and aromatic maturity parameters from the medium molecular (C 14 -C 18 ) and biomarker-range (C 20+ ) hydrocarbon fractions were analysed. Results were compared with results obtained by Lerch et al. (2016), who investigat...

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“…These include 24-norcholestanes (Holba et al 1998a, b) Allard et al 2001), long-chain diols, and mid-chain hydroxyl methylalkanoates (Sinninghe Damst6 et al 2003). The secular increase in 24-norcholestane abundance (Moldowan et al 1991;Holba et al 1998a, b) was observed and linked to the diatom radiation well before a precursor sterol was recognized in a culture of the centric diatom Thalassiosira aff. antarctica (Rampen et al 2005).…”

Section: B Biomarkers and The Rise Of Modern Phytoplanktonmentioning

confidence: 97%

Molecular biogeochemistry of modern and ancient marine microbes

Waldbauer¹

2010

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Biological activity has shaped the surface of the earth in numerous ways, but life's most pervasive and persistent global impact has been the secular oxidation of the surface environment. Through primary production -the biochemical reduction of carbon dioxide to synthesize biomass -large amounts of oxidants such as molecular oxygen, sulfate and ferric iron have accumulated in the ocean, atmosphere and crust, fundamentally altering the chemical environment of the earth's surface. This thesis addresses aspects of the role of marine microorganisms in driving this process. In the first section of the thesis, biomarkers (hydrocarbon molecular fossils) are used to investigate the early history of microbial diversity and biogeochemistry. Molecular fossils from the Transvaal Supergroup, South Africa, document the presence in the oceans of a diverse microbiota, including eukaryotes, as well as oxygenic photosynthesis and aerobic biochemistry, by ca. 2.7Ga. Experimental study of the oxygen requirements of steroid biosynthesis suggests that sterane biomarkers in late Archean rocks are consistent with the persistence of microaerobic surface ocean environments long before the initial oxygenation of the atmosphere. In the second part, using Prochlorococcus (a marine cyanobacterium that is the most abundant primary producer on earth today) as a model system, we explored how microbes use the limited nutrient resources available in the marine environment to make the protein catalysts that enable primary production. Quantification of the Prochlorococcus proteome over the diel cell-division cycle reveals that protein abundances are distinct from transcript-level dynamics, and that small temporal shifts in enzyme levels can redirect metabolic fluxes. This thesis illustrates how molecular techniques can contribute to a systems-level understanding of biogeochemical processes, which will aid in reconstructing the past of, and predicting future change in, earth surface environments. ACKNOWLEDGMENTSI have incurred many debts of gratitude and appreciation over the course of this work. None are greater than those to my advisors, Penny Chisholm and Roger Summons, who allowed and enabled me to pursue such a wide range of scientific interests and offered their help and advice every step of the way. I have been very lucky to have had the chance to learn so much during my Ph.D., and none of that would have been possible without their guidance and support.I have also had the great fortune to know and work with all the members of the Chisholm and Summons labs, who have made this an enjoyable and rewarding place to be. I am especially grateful to Laura Sherman for her skill and dedication in analyzing biomarkers in the late Archean cores -it was truly getting blood from a stone. I was lucky to collaborate with Sébastien Rodrigue, whose expertise and collegiality made the diel experiment even more fruitful than I could have hoped. IntroductionThe coevolution of life and earth surface environments is central to the history and functionin...

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Analysis and occurrence of C26-steranes in petroleum and source rocks

Cited by 84 publications

References 35 publications

Identification of C24 and C25 lanostanes in Tertiary sulfur rich crude oils from the Jinxian Sag, Bohai Bay Basin, Northern China

Identification of C24 and C25 lanostanes in Tertiary sulfur rich crude oils from the Jinxian Sag, Bohai Bay Basin, Northern China

Organic Geochemistry of Barents Sea Petroleum: Thermal Maturity and Alteration and Mixing Processes in Oils and Condensates

Molecular biogeochemistry of modern and ancient marine microbes

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