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30th International Meeting on Organic Geochemistry (IMOG 2021)
- Conference date: September 12-17, 2021
- Location: Online
- Published: 12 September 2021
61 - 80 of 279 results
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The Benefit of Geochemistry and Basin Modeling Integration for Oil & Gas Exploration. The Case Study for Migration Analysis
Authors I. Campoli, D. Kalacheva, N. Morozov, O. Zakharova, A. Gulyaev and F. GaynetdinovSummaryPetroleum systems analysis has been carried out to better understand migration and filling processes in the eastern edge of the West Siberian basin (Yamalo-Nenets Autonomous District, Russia). Within an area of 37 793 km2 two main petroleum kitchens for Upper – Jurassic Bazhenov formation were distinguished which generated petroleum and guaranteed oil volumes to form fields in the Upper - Jurassic section of sedimentary cover. The migration processes are dominated by downward and lateral fluid flow with filled-to-spill mechanism.
The results of this research provided understanding of the lateral limit and maximum distance for migration, which were later supported by the results of drilling of the well. Allowed to evaluate geological risks, correct exploration plans and change priorities in the list of prospects. It also helped to better understand geological reasons for fluid properties in Upper - Jurassic section and plan research of deeper section to find additional source rocks in Lower - Jurassic section which was previously never taken into account in this zone. Later this statement was proved by the results of geochemical pyrolysis analysis. The upgraiding of the model is planned in 2021 to solve more local issues for production process.
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Utilization of Ancient Petrogenic Carbon in Svalbard Sediments, Derived from Glacial Meltwater Streams
Authors M. Ruben and S. DerenneSummaryThe Study addresses the subject of ancient carbon utilization in sediments of Hornsund Fjord, Svalbard. Using a combined approach of biomarker analysis, lipidology, and compound specific radiocarbon dating. We were able to show that the local sedimentary microbes utilize "presumably recalcitrant" petrogenic organic matter for their biosynthesis to a certain extend. Indicating its degradation in the subsurface and hence displaying a not yet accounted source of fissile carbon entering today's carbon cycle.
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δ13C Compositions of Bacteriohopanetrol Isomers Reveal Bacterial Processes Involved in the Carbon Cycle
SummaryBacteria play key roles in the carbon cycle. In many sediments and peatlands, methanotrophic bacteria consume a portion of released methane, reducing the emissions of this potent greenhouse gas. In marine oxygen minimum zones (OMZ) and other anoxic settings, anaerobic ammonium oxidizing (anammox) bacteria remove bioavailable nitrogen while performing chemoautotrophic carbon fixation. Methanotrophic and anammox bacteria synthesize a wide number of complex bacteriohopanepolyols (BHPs), comprising notably several stereoisomers of bacteriohopanetetrols (BHTs), which are used as biomarker lipids. We used a gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) method to measure the δ13C of BHTs of cultured bacteria. These δ13C values were combined with bulk isotopic measurements of the bacterial biomass and δ13C analyses of the bacterial growth substrates to establish carbon isotopic fractionation from substrate to biomass to BHT lipid. We demonstrated that bacteria using different metabolic pathways produced distinct fractionation factors between substrate and BHTs, which potentially allows for distinguishing BHTs produced by ‘Ca. Brocadia’ and methanotrophs from other freshwater producers (e.g. in peatlands). Measurement of BHT-specific fractionation factors allowed us to better constrain the contribution of anammox bacteria to fixed carbon in OMZ. This work expands the application of BHT isomers to isotopically identify carbon cycle processes.
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Terrestrial Temperatures Peak in the First Millenia After the Cretaceous-Paleogene Boundary
SummaryThe Cretaceous-Paleogene (K-Pg) boundary extinction represents one of the most severe, with approximately 75% of life on earth suffering extinction. An new terrestrial mean annual air temperature (MAAT) record based on branched tetraether data from southern Saskatchewan (Canada) permits, for the first time, the recognition of a distinct episode of rapid global warming in the first approximately 1 ka of the Paleogene, which is attributed to a rapid release of CO2 at or around the K-Pg boundary. Irrespective of the source(s) of CO2, the extinction on land may therefore have been partly driven by MAATs exceeding a threshold for ecosystem resilience. These data are the first in their kind at this resolution, providing new boundary conditions of absolute values, and rates of temperature change. Further studies of terrestrial MAAT at a similar resolution will be essential for demonstrating the unparalleled trends observed in our record to be a global phenomenon.
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Fuelling Earliest Life — Volatile Organic Compounds in 3.5 GA Old Fluid Inclusions
Authors H. Mißbach, J. Duda, A.M. Van den Kerkhof, V. Lüders, A. Pack, J. Reitner and V. ThielSummaryIt is widely accepted that small organic molecules played a central role in the emergence of life on Earth. As yet, however, there has been no conclusive evidence for the existence of the discussed relevant candidate molecules on early Earth. Here we report on indigenous, biologically-relevant organic molecules in 3.5 Ga old barite-hosted fluid inclusions from the Dresser Formation in Western Australia. We characterized the organic inventories by combining fluid inclusion petrography, stable isotope analysis and different GC-MS techniques. Our study establishes a primary origin of the fluid inclusions. They contain CO2, H2S and H2O, minor amounts of COS, CS2, N2, and CH4 as well as various oxygen and/or sulfur containing organic molecules. Notably, most of the identified compounds could have served as substrate for purported ancestral sulphur and methanogenic metabolisms. Perhaps most remarkably, the fluid inclusions also contain the stable building blocks of methyl thioacetate which is a potential key-agent in the emergence of life. Thus, our study provides the first robust evidence for the existence of such organic compounds on the early Earth and strongly supports the idea that microbial life in the 3.5 Ga old Dresser Formation was linked to hydrothermal seepage.
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Long-Term Anoxia Driven by High Temperature of Equatorial Atlantic During Cenomanian Leading up to OAE 2
Authors M.A.F. Abraham, D. Naafs and R. PancostAbstractOceanic Anoxic Event (OAE) 2 occurred during the Cenomanian/Turonian and marks one of the most significant perturbations of Earth’s system of the last 250 million years. Although the burial of black shales in the marine environment under depleted (bottom) water column oxygen conditions was widespread during OAE 2, the state of anoxia in the million years leading up to OAE 2 and the correlation between anoxia and temperature are poorly constrained. Here, we report long-term biomarkers records of (a) water column anoxia, (b) water column and photic zone euxinia (PZE), and c) TEX86-based sea surface temperature (SST) from Demerara Rise (ODP Site 1258) that span the Albian to Turonian, including OAE 2. Our data suggest a depositional environment under long-term anoxic condition at Demerara Rise during the Cenomanian as indicated by elevated total organic carbon content (up to 10 wt.%) and episodic occurrence of the biomarkers lycopane and 28,30-bisnorhopane, which at present are found in the anoxic marine such as Black Sea (Wakeham et al., 1993) and Monterey Formation (Schoell et al., 1992), respectively. The extent of water column anoxia gradually intensified and peaked during OAE 2 when the presence of hopanoid thiophenes and free isorenieratane indicate euxinic conditions in the water column, at times reaching the photic zone. This long-term progression of marine de-oxygenation coincides with a gradual increase in SSTs at the site. TEX86-based SSTs indicate a long-term warming of ∼ 7 °C during the Cenomanian to maximum values of 41 °C during OAE 2. The abrupt declined in SSTs following OAE 2 during the Turonian indicates termination of long-term anoxia via re-oxygenation of water column in phase with low TOC and absence of anoxia and euxinia biomarkers. This study highlights the impact of Earth’s climate state on marine oxygenation with an increase in temperature driving the ocean’s state from hypoxia into severe anoxia and eventually euxinia, likely due to weathering feedback mechanisms related to warming and changes in the hydrological cycle.
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Changes of Biomarkers, Isotopes and Macerals of Polish Coals and Shales: Maturation Simulated by Hydrous Pyrolysis
Authors M. Kotarba, M. Słowakiewicz, K. Jurek, M. Waliczek and D. WięcławSummaryThe bitumen yields of Carboniferous coals and shales from USCB and LCB after 330oC HP are higher than in initial coals and shales and somewhat higher than of coals and shales after 360oC HP. The distribution of exsudatinite in coals is higher at 330°C and decreases at 360°C HP. Contrary to shales at 360°C HP the exsudatinite content slightly increases. This phenomenon could be caused by the presence of clay minerals in shales which have a general retention effect during hydrocarbon generation. The results of biomarker and isotope analyses reveal that bitumen is always co-genetic with corresponding kerogen in coals and shales, and their deposition was in a brakish-lacustrine environment, and the microbially reworked organic matter could be caused by: (i) contribution of planktonic or benthic algae organic matter, (ii) more anoxic conditions in sedimentation basin, which impede bacterial growth and reworking of organic matter and (iii) contribution of terrestrial organic matter was higher than in other cases, and more organic matter could preserve in primal form.
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Molecular Investigation of Archaeological Ambers from Alsace (Ne France): Origins and Alteration Processes
Authors S. Schmitt, P. Adam, P. Schaeffer, C. Féliu, N. Schneider-Schwien, D. Minni, M. Châtelet, E. Boes, D. Azar and A. NelSummaryA set of amber samples collected from archaeological burials at three different sites in Alsace (NE France) and dated back to the Bronze Age and the high Middle Age, as well as European ambers from potential geological sources have been investigated. Based on GC-MS analysis of lipid biomarkers occurring in the solvent extract and of those released by chemical degradation which comprised various diterpenoids and succinates, it appears that the archaeological samples correspond to Baltic amber, confirming that the Baltic region was a source of amber for Alsace, at least during the Bronze Age and the High Middle Age. Identification of the source of ambers using lipid distributions was possible despite alteration of the molecular signatures by natural degradation processes.
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HYDROCARBON PROPERTIES OF THE BAZHENOV FORMATION SOURCE ROCKS WITH DIFFERENT MATURITY
Authors M. Tikhonova, A. Kalmykov, O. Vidishcheva, D. Ivanova, V. Levkina, R. Borisov and G. KalmykovSummaryBazhenov formation source rocks from wells with different maturity of organic matter were investigated by sequential extraction. Hydrocarbons extracted with hexane from open pores and with chloroform from blocked pores were investigated by FID-GC and GC-MS methods. It was found that hydrocarbons composition in open and blocked pores depends not only on maturity, but also on lithological composition of rocks and migration processes. In one well not only maturation, but also sedimentary condition biomarker parameters may vary through the depth of section. Reservoirs are filled with migrated hydrocarbons, that are of higher maturity and contain higher amount of n-alkanes with shorter chains in hexane extracts. Hydrocarbons formed in continental conditions were also found in the rocks at the bottom of Bazhenov formation, formed in marine conditions, which means there was another source rock deeper than Bazhenov formation. Concentration of silica, carbonates and pyrite affect the processes of hydrocarbons generation and influence some biomarker parameters values. That is lithological and reservoir properties of the Bazhenov source rocks as well as maturity of organic matter should be analyzed for investigation of oil and gas generation and migration processes.
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The Stable Carbon Isotope Geochemistry of Natural Gas After 20 Years of Shale Gas Development
Authors J. Cesar, B. Mayer and O. H. ArdakaniSummaryThis study discusses the new perspectives on the stable carbon isotope distribution in natural gas hydrocarbons, with special focus on the evidence of a tendency to equilibrium isotope fractionation in gases from low-permeability hydrocarbon reservoirs. It also describes how the isotope equilibration expresses (or not) in the molecular composition of the produced fluids.
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STRUCTURAL INVESTIGATION OF THE MACROMOLECULAR COMPONENT OF BALTIC AMBER BY SELECTIVE CHEMICAL DEGRADATION
Authors S. Schmitt, P. Schaeffer, P. Adam, C. Féliu, N. Schneider-Schwien, D. Minni, M. Châtelet, E. Boes, D. Azar and A. NelSummaryThe constitution of Baltic amber, the role of succinic acid and, more generally, of ester bonds in the constitution of macromolecular components of amber has been further investigated by chemical degradation of the solvent insoluble part of Baltic amber using butanolysis (BuOH/HCl). Succinic acid derivatives were the sole compounds released upon butanolysis whereas other compounds which could correspond to the alcohol counterparts of succinates could not be detected by GC-MS. This result indicate that these counterparts are all located on high molecular weight structural moieties. Succinic acid thus plays a key role as cross-linking agent between oligomeric structural moieties based on diterpenoids necessarily bound by at least one non-hydrolysable C-O or C-C bond.
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New Paleoenvironmental Proxies for the Permian Irati Black Shales Based on Acidic O1 and O2 Compounds Assessed by FT-ICR-MS
SummaryVariations of the acidic polar composition of the Early Permian Irati black shales and Serra Alta shales were assessed by ESI(-) FT-ICR-MS to investigate their significance for the paleoenvironmental studies by comparison with known features in the northeastern and central-eastern Paraná Basin (Brazil). The high O>2 classes in the Serra Alta shales points to high input of terrigenous OM deposited in oxic waters. In addition, seven parameters based on O1 and O2 compounds are proposed as new paleoenvironmental proxies: phenol index (%DBE 4; O1 class); C27/C28 DBE 4 (O1 class); C27/C28 DBE 5 (O1 class); Even/OddFA; TARFA Odd (terrigenous/aquatic ratio); C36 hopanoic acid index; and hopanoic/steranoic acids ratio. Higher values of the phenol index and the TARFA indicate higher land plant input during the final black shale deposition, and higher Even/OddFA to northeastern basin samples reflects their higher content of terrigenous OM. Furthermore, variations of C27/C28 (DBE 4) and C27/C28 (DBE 5) is useful to reconstruct paleosalinity, in which higher values indicate higher salinity. The C36 hopanoic acid index is higher for the marine hypersaline basal samples from the northeastern basin, while a significant bacterial biomass signal is stored as a higher hopanoic/steranoic acids ratio for central-eastern basin samples.
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OILS OF NONMARINE GENESIS WITH AN ABNORMALLY LIGHT ISOTOPE COMPOSITION OF CARBON
Authors I. Goncharov, R. Kashapov, S. Fadeeva, A. Litvinova, A. Zherdeva, K. Kozyreva and N. OblasovSummaryThe results of the study for oils formed by organic matter of non-marine origin, which accumulated under moderately oxidizing conditions, are presented. Oils are characterized by an increased content of a light carbon isotope, which is unusual for hydrocarbons formed in such conditions.
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Carbon Isotopic Composition and Components of the Petroleum Gases from Fields in the Western Pre-Caucasus Area (Russia)
Authors I. Goncharov, N. Oblasov, M. Veklich and I. EftorSummaryThis study is about differences and similarities in the isotopic and component composition of the petroleum gases from fields in the Western Pre-Caucasus area. These gases were differentiate into three genetic types. The 1st genetic type (Akhtyrsky type) were generated by the rocks of the Middle Eocene Kuma Formation. Gases with the higher δ13C values of gas components from ethane to pentane were assigned to the 2nd (Sladkovsky) genetic type. These gases are associated with oils, the source of which was marine organic matter but the exact stratigraphic confinement of the source rock remains unclear. And the 3rd genetic type of gases (Nikolaevsky type) which the initial organic matter associated with higher terrestrial plants, which accumulated under oxidizing conditions (for oils Pr/Ph = 3.1–4.3, C27–C28–C29 steranes is 0.23–0.22–0.55). The source rock of these gases and oils remains unknown, but its age should be no younger than the Lower Cretaceous.
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OBTAINING THE KINETIC SPECTRUM OF ORGANIC MATTER AT DIFFERENT STAGES OF NATURAL THERMAL EVOLUTION
Authors R. Kashapov, I. Goncharov, N. Oblasov and V. SamoilenkoSummaryThe dependence between the Arrhenius constant and the activation energy is obtained using the results of kinetic studies of the Bazhenov formation rocks at various stages of catagenesis. Based on this dependence, a kinetic spectrum is obtained that reflects the realization of the generation potential of organic matter in the process of thermal evolution.
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Metagenomic Insight into the Metabolic Activities of Potential Btex-Degrading Populations
By M. EzeSummaryEnvironmental contamination by petroleum hydrocarbons is of concern due to the carcinogenicity and neurotoxicity of these compounds. Successful bioremediation of organic contaminants requires bacterial populations with degradative capacity for these contaminants. Through successive enrichment of microorganisms from a petroleum-contaminated soil using diesel fuel as the sole carbon and energy source, we successfully isolated a bacterial consortium that can degrade diesel fuel hydrocarbons. Metagenome analysis revealed the specific roles of different microbial populations involved in the degradation of benzene, toluene, ethylbenzene and xylene (BTEX), and the metabolic pathways involved in these reactions. One hundred and five putative coding DNA sequences (CDSs) were identified as responsible for both the activation of BTEX and central metabolism (ring-cleavage) of catechol and alkylcatechols during BTEX degradation. The majority of the CDSs were affiliated to Acidocella, which was also the dominant bacterial genus in the consortium. The inoculation of diesel fuel contaminated soils with the consortium resulted in approximately 70% hydrocarbon biodegradation, indicating the potential of the consortium for environmental remediation of petroleum hydrocarbons.
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GASEOUS POLLUTANTS GENERATED DURING DRY AND HYDROUS PYROLYSIS OF COAL WASTE: SIMULATION OF THE SELF-HEATING PROCESSES
Authors D. Więcław, K. Jurek, A. Kowalski, E. Bilkiewicz, M.J. Fabiańska, M. Misz-Kennan and J. CiesielczukSummaryPyrolysis experiments were conducted without and with water in temperatures 250, 360 and 400oC during 72 h to simulate pollutants generation from self-heating coal wastes under oxygen-depleted conditions. The molecular composition of gases generated during these experiments and their relationship with the amount of organic matter in the rock (TOC), its maturity, the temperature of the process and the influence of the water was determined. Alkanes up to C8 and alkenes to C4 were identified. The sulphur-containing compounds comprise inorganic (H2S, COS/SO2) and organic (methyl- and ethyl mercaptans, and methyl-, ethyl-, propyl- and butyl sulphides) components. The H2, CO, CO2 and N2 were recorded among the inorganic gases. The molecular composition of generated gases strongly relates to the temperature of the process. The concentration of usually increase with the increasing temperature of pyrolysis. Presence of water and elevated TOC amounts boost generation S-compounds (dominated by H2S). Presented results helped to understand and evaluate the emission of gaseous pollutants during pyrolysis of the stored coal wastes induced by self-heating. The most dangerous to the environment is the 300–400°C regime connected with the emission of elevated concentrations of hydrocarbons and S-containing compounds, especially from TOC-rich rocks.
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GEOCHEMICAL CHARACTERISTICS AND SOURCE DISCRIMINATION OF DEEP PERMIAN OILS FROM WELL XJC 1 IN THE SOUTHEASTERN JUNGGAR BASIN
Authors H.J. Zhang, S.M. Li and L. ZhangSummaryThe Junggar Basin is one of the most important superimposed basins in southeastern China, characterized by multiple source rocks and hydrocarbons productive horizons. Well XJC1 is one of the recently drilled wells with deep commercial tight oil/gas (>4000m) discovered in the Perman Lucaogou Formation (P2l) in the southeast of the basin, which suggests a great petroleum potential in this relatively low-level exploration area. Oil-oil and Oil-source rock correlation showed that the P2l oil from the XJCJ well were sourced from the P2l argillutite, which have a high hydrocarbons generation potential with large scale and a relatively wide range of thermal maturity (low to high level). It suggests a great petroleum exploration potential about normal and unconventional hydrocarbon resources in the southeastern Junggar Basin. This study would be helpful for the further petroleum exploration and exploitation in the area.
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Cyanobacterial Aromatic Carotenoids
Authors R. Summons, F. Husain, X. Cui, S. Rohret, X. Liu, P. Welander, G. Shen and D. BryantSummaryContrary to common perceptions, cyanobacteria can be the source of aromatic carotenoids preserved in sediments. Their distribution patterns differ, somewhat, from those produced by the phototrophic sulfur bacteria and are distinguished by the presence of C38 and C39 compounds which are diagenetic products of mono- and dicarboxylic acid precursors. Cyanobacterial aromatic carotenoids are most in evidence in samples from lacustrine environments and their existence likely explains some of the carbon isotopic variability of carotenoid assemblages previously thought to be derived from Chlorobi.
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Application of Biomarkers and Compound Specific Sulfur Isotope in Oil-Source Rock Correlation in the Wenliu Oilfield, Bohai Bay Basin
More LessSummaryDongpu Depression is an important petroliferous depressions in the Bohai Bay Basin, eastern China, which is a typical saline lacustrine depression. Wenliu Oilfield is the biggest oilfield in the depression. There is still some controversy about the oil source for the Wenliu oilfield. The dispute is focused on the location (in-situ or the adjacent Qianliyuan Sag) and the horizons (the Es3M or the Es3L-Es4u) of the key source rocks. Quite a few geologists suggested that the Es3M in-situ should be the most important source rocks, which is primarily dark shales with great hydrocarbon generation potential. To help unravel the origin and source rocks of the Wenliu oils, a total of 44 rock samples and 66 oil samples were collected for study by conventional geochemical methods combined with compound specific carbon/sulfur isotopic analysis. We suggested that the Wenliu Oils are mixed sources derived from both the Es3M and the Es3L-Es4U strata, and the latter should be responsible for the majority of the crude oils in the Wenliu Oifleld based on oil-oil and oil-source correlation as well as semi-quantitative comparison of biomarkers abundances. The results would be instructive for further petroleum exploration and petroleum resource evaluation in the area.
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