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30th International Meeting on Organic Geochemistry (IMOG 2021)
- Conference date: September 12-17, 2021
- Location: Online
- Published: 12 September 2021
1 - 50 of 279 results
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PETROLEUM SYSTEM OF DUVA OIL AND GAS FIELD IN NORTHERN NORTH SEA, NORWAY
More LessSummaryThe Duva oil and gas field is located at ca. 5 km northeast of the Gjøa field in the Northern North Sea. The reservoir contains oil and gas in a turbiditic sandstone of the Early Cretaceous Agat formation. Highly waxy oils were collected, and its geochemical characteristics were investigated by GC and GC-MS analyses. We performed position-specific isotope analysis (PSIA) on a gas sample from the Duva field to identify the effective source rock of the gas. 2-dimensional basin modelling was conducted to understand the petroleum system including complex migration and accumulation processes of the Duva field. The abnormally waxy oil in the Duva field possibly formed by the large input of terrestrial organic matter into the Upper Jurassic marine source rocks and/or the evaporative migration fractionation based on the biomarkers and carbon isotopic compositions. Intramolecular carbon isotopic compositions of propane in the gas sample suggested that the gas in the Duva field was generated from coals in the Middle Jurassic or older. A late charge of the gas derived from the coaly source rock into an initial oil accumulation may have caused the evaporative fractionation resulting in the formation of the waxy oil in the Duva field.
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Role of Bitumen and Nsos During Thermal Maturation of a Lacustrine Type-Ii Shale in Semi-Open Pyrolysis Experiment
More LessSummaryBy taking the Chang7 shale in the Ordos Basin of China as an example, the decomposition pathway of lacustrine Type-II kerogen was studied. Results show obvious characteristics of concurrently generation of bitumen and oil and simultaneously generation of NSOs and HCs during the initial kerogen decomposition. The results not only contradicts with product-precursor relationship between the bitumen and oil of lacustrine Type-I and marine Type-II kerogen, but also negates the sequential reaction model between NSOs and HC of lacustrine Type-I kerogen, marine Type-II kerogen, and Type-III lignite.
The reaction process of the Chang7 shale under semi-open pyrolysis conditions follows the “alternate pathway”, in which hydrocarbons can be formed immediately from kerogen in parallel with NSOs and the formation of the two species are controlled by bond-breaking reactions independent of each other. From this point of view, the Chang7 kerogen is likely to contain sufficient branched structures that bond-breaking has a high possibility of generating HC at the onset of pyrolysis. The mechanism not only applies to the Chang7 shale, but also can be extended to source rocks of the same kerogen type worldwide. This work has broadened the understanding of the decomposition pathway of a less studied kerogen type.
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Chemical Structure Evolution of Lacustrine Type-Ii Kerogen Under Semi-Open Pyrolysis as Investigated by 13C Nmr and Ft-Ir
More LessSummaryThis study aim to investigate the structural changes of a lacustrine Type-II kerogen, by taking the seventh Member of the Triassic Yanchang Formation in the Ordos Basin (Chang 7 Shale) as an example. Integrated analysis including elemental analysis, programmed pyrolysis (Rock-Eval), FT-IR, and 13C NMR were conducted on the unheated and post-pyrolysis rocks and kerogens.
Results show that before the peak hydrocarbon-generating stage (Ro < 0.6%), defunctionalization of oxygen-containing functional groups, which generates water, CO2 and NSOs, occurs simultaneously with the detachment of short aliphatic side chains and small aromatic rings, which generates volatile fractions (C6-C14, C15+ sat and C15+ aro), suggesting that the Chang7 kerogen is highly branched. During the peak hydrocarbon-generating stage (0.6–1.09 %Ro), the concurrent breakage of weak cross-link bonds and long aliphatic chains lead to the simultaneous peak generation of liquid hydrocarbons and NSOs, indicating the highly cross-linked features of the Chang7 kerogen. After the peak hydrocarbon-generating stage (Ro > 1.09%), the reactions in the previous two stages produce a highly aromatic kerogen. The increased aromaticity of the highly matured kerogen is likely to be caused by aromatization or dehydrogenation of hydroaromatics and coking of aromatic bitumen, not by fusing or condensation of aromatic rings.
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GEOCHEMICAL CHARACTERISTICS OF ORGANIC MATTER IN THE ACHIMOV DEPOSITS OF WESTERN SIBERIA AND THEIR OIL AND GAS POTENTIAL
By S. PunanovaSummaryThe report considers the geochemical features of the Achimov deposits of the West Siberian oil and gas basin, occurring in the lower Lower Cretaceous. The Neocomian oil and gas complex in Western Siberia has been studied relatively fully, but the geochemical features of the Achimov deposits continue to remain insufficiently studied. The Achimov strata lies at a depth of 2500–4000 m and is represented by layers of dense fine-grained sandstones with clay-carbonate cement, separated by interlayers of clays of various thicknesses (up to 10–15 m). A characteristic feature of the Achimov deposits is the clinoform structure of the traps, lithological inconsistency, and variable thickness. The presence of source deposits and the degree of their catagenetic transformation make it possible to consider the Achimov productive complex as completely independent. The OM of the Achimov deposits is characterized by moderate catagenesis and mixed sapropelic-humus composition.
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Trace Elements of Naphthides as Indicators of Geochemical Processes
By S. PunanovaSummaryThis report highlights the following aspects of the trace element (TE) composition of naphthides: 1. genetic relationships of bitumoids with the composition of generated oils; 2. dynamics of changes in the TE composition of naphthides during catagenic and hypergenetic transformations; 3. correlation dependences of the TE compositions of naphthides with the composition of various substances. The composition of the TE of oils and bitumoids has long been successfully used in petroleum geochemistry for solving various geological and geochemical problems. That is why the use of data on the TE composition of naphthides is relevant and well-grounded.
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TRACE ELEMENT COMPOSITION OF NAPHTHIDES IN LIGHT OF THE PERIODIC LAW OF CHEMICAL ELEMENTS
By S. PunanovaSummaryThis report discusses the features of the distribution of trace elements (TE) in naphthides in connection with the Periodic Table of D.I. Mendeleev. There are several generally accepted geochemical classifications of elements based on this Periodic Law. More than 60 elements have been identified in oil and its derivatives. Only technical limitations prevent the detection of the other elements in D.I. Mendeleev’s Periodic Table of the Elements within oils. The concentrations of these elements are low, but they carry important information. In petroleum geochemistry, for Zn, Br, Mn, Cu, I, As, B, F, Pb, Ti, V, Cr, Ni, Sr and other elements occurring in living matter from 1 to 100 ppm, the term “Trace elements”, or “Spurenelementen”, has become widely appropriated.
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Applications of Higher Diamaondoids within and Outside of the Petroleum Industry
Authors J. Dahl, J.M. Moldowan and R.M.K. CarlsonSummaryThe recent availability and property determination of petroleum-derived higher diamondoids has led to a number of applications and potential applications both within and outside of the petroleum industry. These include: correlation of highly-mature fluids, correlation of mixed-maturity oils, photo-emitters, field emitters, seeds for growing small diamonds with color centers for quantum information, pharmaceuticals, components in new polymers, components in lithium-ion batteries and catalysts. This presentation is an overview of these applications and the physical properties leading to them
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Identifying Plant Wax Inputs in Lake Sediments Using Machine Learning
Authors M. Peaple, J. Tierney, D. McGee, T. Lowenstein, T. Bhattacharya and S. FeakinsSummaryWe trained models to identify plant type based upon modern leaf wax chain length distributions. We then applied these models to ancient waxes extracted from a core collected from Searles Lake, California, USA, to reconstruct paleovegetation. We validated our models by comparing our vegetation results to the ACE index, a proxy for lake salinity also measured from lake core samples.
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Light Hydrocarbons and Their Message on Geochemistry of Oils and Condensates from the Bovanenkovskoye Field (West Siberia)
Authors A. Burukhina and E. FursenkoSummaryThe studied Bovanenkovskoye oil-gas-condensate field is located at the Yamal Peninsula – in the north of West Siberia, where a new gas-production centre is being formed. The aim of the study is to conduct geochemical type assignment of oil (5) and condensate (10) samples from the Lower Cretaceous (K₁al – 2, K₁a – 3, K₁g – 3), Middle (J₂bt – 3, J₂b – 3), and Lower Jurassic (J₁p – 1) deposits, using data about their properties and composition (distribution of n-alkanes, i-alkanes, steranes, terpanes, arenes, and, mainly, of light hydrocarbons C₄–C₈). In the presented research, the use is made of GC and GC/MS analyses of crude oils (condensates) and their hydrocarbon fractions. The obtained results suggest the hydrocarbon formation in the Bovanenkovskoye field from a single center of oil and gas generation due to the terrestrial organic matter of the Lower and Middle Jurassic strata (Malyshevka, Layda formations) and a significant contribution of the aquatic organic matter from the Upper Jurassic strata (Bazhenov formation) to the generation of the Aptian condensates.
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GEOCHEMISTRY OF PETROLEUM RESINS AND ASPHALTENS BASED ON FLASH-PYROLYSIS PRODUCTS
Authors E. Fursenko, A. Burukhina and K. DolzhenkoSummaryThe objects of the research are resins and asphaltenes (RAS) extracted from West Siberian oils. The obtained results reveal the genetic affinity of hydrocarbon fractions and the RAC of the studied oils.
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Organic Matter Occurrence and Alteration in the Uranium-Rich Alum Shale Formation: Implications for Microbial Activity
More LessSummaryThe Early Palaeozoic Alum Shale Formation in northwestern Europe is rich in uranium up to several hundreds of ppm. Despite the absence of higher land plant precursors, the primary Type II kerogen in the Alum Shale has an abnormally strong aromatic character even at low thermal maturities, probably due to α-particle bombardment.
FT-ICR-MS data reveal that the macromolecules in the uranium-rich Alum Shale samples are less alkylated than less irradiated counterparts, and that oxygen containing-compounds are enriched in the uranium-rich samples but are not easily degradable into low-molecular-weight products due to irradiation-induced crosslinking.
Despite strong organic matter alteration, CO2 and CH4 are formed using U-rich samples in incubation experiments, and DNA-based high-throughput sequencing allows a detailed phylogenetic characterization of the indigenous microbial communities with implications of an uranium-adapted biosphere.
The alteration of macromolecular organic matter in the Alum Shale Formation is suggested as an Earth analogue of the Martian surface, in response to α-particle irradiation. Especially a comparison of potential habitats on the Martian surface with Kolm nodules of the Alum Shale in terms of irradiation dosage and organic geochemical characteristics reveals that they have received similar levels of irradiation.
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The Effect of Elemental Sulfur on the Thermal Evolution of Steroids
More LessSummarySteroids are one of the most important families of biomarkers, and have been widely used in petroleum exploration, paleoenvironment reconstruction and the research of eukaryotic evolution in early Earth, etc. The general evolution pathways of natural steroids were initially speculated on from their distribution in geological samples. Previous researchers further clarified the evolutionary pathways of steroids through laboratory thermal simulation experiments. However, the role of sulphur/sulphur-bearing compounds on the thermal evolution of steroids was still not well understood. We therefore carried out research on the thermal evolution pathway of steroids with and without elemental sulfur using gold tube pyrolysis experiments. The results show that elemental sulfur significantly accelerated the thermal evolution process of steroid compounds, and can induce aromatization starting with the C-ring monoaromatic steroids. The common coexistence of sterols, sterenes, steranes and aromatic steroid compounds in many immature geological samples may also be the result of the presence of sulfur. The isomerization of steranes was significantly different with and without sulfur. Therefore, when using sterane isomerization parameters to evaluate the maturity of geological samples, it is necessary to take more factors into consideration such as the lithofacies, including the presence of sulfur.
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A Comparison of Maturity Between Oil and Source Rock in the Shale-Oil System of the Qingshankou Formation, Songliao Basin
More LessSummaryDetermination of oil maturity is of great significance for understanding the origin and evolution stage at which the oil is generated, and is one of major topics in petroleum geochemistry research. Due to oil migration, oils in reservoirs most likely are mixtures of oils generated at different thermal maturities or by different source rocks, and it is usually hard to establish relationship between source rock and oil with respect to thermal maturity. In this paper, source rock maturity was compared with that of intra-source oil (i.e. shale oil), providing preliminary implications for further study.
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Novel Approach to Reservoir Continuity Evaluation Through Gc-Ms Geochemical Fingerprinting
Authors P. Franco, I. Colombo and R. GalimbertiSummaryGeochemical fingerprinting of reservoir fluids represents a widely adopted methodology to address questions related to reservoir geochemistry, such as the assessment of continuity through the hydrocaron pool. This technique is based on the general assumption that disconnected reservoirs will produce oils with significantly different molecular fingerprints; therefore, the assessment of such differences can be used to infer the presence of compartmentalization. Currently, one of the main limitations of this technique resides in the need of representative reservoir fluids to test, which are often unavailable. The present work deals with the develompment of a GC-fingerprinting approach aimed to the analysis of residual oil in cuttings, wich allows to overcome the limitation related to the lack of proper reservoir oil samples. The main challenges, possible solutions and current limitations of this approach will be presented, along with a representative case history showing the successful application of this methodology and its potential.
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How Do the Groundwater Level Fluctuations May Affect the Remobilization of Lnapls?
Authors A. Cavelan, P. Faure, C. Lorgeoux, S. Colombano, J. Deparis, H. Davarzani, N. Enjelvin, C. Oltean, A. Tinet and F. GolfierSummaryLight non-aqueous phase liquids (LNAPLs) are one of the most common sources of soil pollution worldwide. The Intergovernmental Panel on Climate Change (IPCC) predicts a significant increase of groundwater level fluctuations' intensity by 2100 that may greatly favor the remobilization of these contaminants in the environement. Yet, the effect of groundwater tables fluctuations on the LNAPL mobilization is not fully understood. To this aim, a new original experimental system combining in situ physical-chemical, geochemical, and indirect geophysical measurements was developed at the GISFI station, Homécourt, France to assess the effect of the groundwater level variations dynamic, under current and climate change conditions, on the LNAPL remobilization. Attention will be paid, especially, to the evolution of the concentration and composition of the dissolved LNAPL phase over time. Measurement, and monitoring of the pure LNAPL phase thickness and chemical composition variation will be also monitored. Numerical simulations of the LNAPL transport through the contaminated soil will also be carried out. These experiments should provide a better understanding of the fate of these hydrocarbons at contaminated soils and thus, a better assessment of the environmental risks associated with these contaminated sites and their evolution in the climate change context.
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Occurrence and Identification of Five Series of Benzohopanes in Sediments
Authors L. Jiang, L. Li, H.P. Nytoft and S.C. GeorgeSummaryBenzohopanes are common compounds in sediments and crude oils. Three series of benzohopanes have been reported so far, but we have found two new series of benzohopanes in lacustrine sediments. This abstract exhibits the occurrence and identification of five series of benzohopanes in lacustrine shales, oil shales and mudstones.
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Study on oil source in the Jiufengshan Formation of the Dayangshu Basin, China
More LessSummaryDayangshu Basin is located in Eastern Inner Mongolia Autonomous Region, China. It is a late Mesozoic basin that is covered by volcanic rocks. The tectonic movement is violent. Fault activities control the formation and development of the basin. Volcanic activity runs through the whole process of basin formation. It is of great significance that study on the characteristics of source rocks and oil-gas sources in the Dayangshu Basin for evaluating the oil-gas exploration potential, understanding the oil-gas generation and evolution of the volcanic strata in the eastern basin of China.
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The Geochemical Characterisitics and Origin of Ordovician Ultra-Deep Natural Gas in Shuntuoguole Area, Nw China
More LessSummaryAll the natural gases in Shuntuoguole area are oil-type gases, in which the gases in SB area are wet gas with kerogen-cracking dominated, whereas the gases in ST, SN, GL, GC areas are dry gas originated from oil-cracking. Both the wet and dry gases in Shuntuoguole area are sourced from Lower Cambrian Yuertusi Formation.
The distribution of two types natural gas is correlated with the present strata temperature and (or) paleo-temperature of Ordovician. The present strata temperature and paleo-temperature of Ordovician in SB area ranged from 150∼160℃, 170∼180℃, unreached the temperature of oil-cracking in large scale. However, the paleo-temperatures of Ordovician in ST, SN, GL and GC areas have exceeded 180℃ and present strata temperatures are high with temperature about 200℃, resulting the paleo-oil reservoir cracking in large scale. Thus, from SB to ST to SN to GL to GC areas, the fluid phase changed from light oil to volatile oil to condensate to dry gas phase gradually.
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Geochemical Analysis of the Q Source Rocks of Oman: A 40-Year-Old Mystery.
Authors M. Al Ghammari, G. Siavalas, A. Bell and M. SpaakSummarya geochemical study on source rocks found in the eastern flank of Oman Ghaba Basin and effort to correlate this source rock to Oman oils families. we believe that this source rocks is the source for the well known Q oil family in Oman which has been known since 40 years but no source rocks were linked to it.
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Molecular Significance of Rock-Eval® S2 Pyrograms
Authors J. Jacob, F. Delarue, Y. Copard, C. Le Milbeau, L. Grasset and P. BrockmannSummaryWe here present original results acquired through a simple setup that allows obtaining molecular explanations of the mathematical deconvolution of Rock-Eval S2 pyrograms. This approach provides clues to the intimate nature of organic matter and bridges a gap between bulk and molecular information.
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MOLECULAR BIOMARKERS IN FOSSIL AND MODERN CARNIVOROUS COPROLITES
Authors C. Gauthier, J. Jacob and J. BrugalSummaryWe here present new results on biomarkers preserved in fossil and modern coprolites from carnivorous animals
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FIRST INSIGHTS INTO ORGANIC GEOCHEMISTRY OF THE LATE NEOPROTEROZOIC KHARAYUTEKH FORMATION, NORTHEASTERN SIBERIA
Authors T. Parfenova and D. MelnikSummaryThe results of the first geochemical investigation of the organic matter from the Late Neoproterozoic Kharayutekh Formation widely distributed in the Kharaulakh Ranges of northeastern Siberia are presented. Data shows that the Middle Kharayutekh Member can be regarded as a potential source rock. Natural bitumen and/or gas deposits associated with the realisation of the hydrocarbon generative potential of the Kharayutekh rocks can be found in the Arctic region of Northeastern Siberia.
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CATAGENETIC EVOLUTION OF THE COMPOSITION AND STRUCTURE OF ASPHALTENE COMPONENTS OF ORGANIC MATTER
Authors L. Borisova and I. TimoshinaSummaryThe revealed tendency of changes in the elemental and structural-group composition of asphaltene components of the organic matter of different origins at different stages of transformation is concerned with:
- the formation of the composition and structure of OM asphaltenes occuring at the stage of diagenesis, which are largely predetermined by the initial substrate of the organic matter;
- the identified trend for polymer condensation changes in both genetic types of OM at the initial stage of thermocatalytic transformations;
- the directed process of asphaltene graphitization taking place during catagenesis, which is accompanied by a decrease in hydrogen content, an increase in the proportion of aromatic and condensed structures among them, and is characterized by a decreasing role of alkyl and cycloalkyl hydrocarbon substituents of their molecules.
A linear dependence of the change in composition and structure during thermocatalytic transformations which will make it possible to develop catagenesis grades based on the data obtained from the study of asphaltenes within the entire range of stages.
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Ecosystem and Hydroclimate Conditions from a New Early Human Site at Olduvai Gorge (AGS, BED I, 1.84 Ma)
More LessSummaryIn this study, we focus on a newly discovered Early Pleistocene archaeological site – AGS (Alberto Gómez Site) – at Olduvai Gorge in Northeast Africa to identify coeval landscape resources via a multi-proxy perspective. We explore the distribution of four major compound classes (n-alkanes, n-alcohols, n-alkanoic acids, and sterols) and leaf-wax δ13C-δD compositions of 24 paleosoil samples excavated from a 24 m2 archaeological transect at AGS. Our multi-proxy geochemical interpretations of the Olduvai Zinj-Paleolandscape at 1.89 Mya reveal that AGS was located near the river/lake margins and was dominated by C3 aquatic plants and C4 grasses. Given the mosaic patchy ecosystem across the Zinj-Paleolandscape soil horizon and the molecular fossils studied here at AGS, we hypothesize that hominins at Olduvai Gorge, 1.9 ma years ago, selected the locations for their main activities conditioned by the presence of water resources within the landscape.
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BHT-x: Constraining its Application as a Lipid Biomarker for Marine Anammox Using a Modern Water-Column Oxygen Gradient
Authors Z. Van Kemenade, L. Villanueva, E. Hopmans, P. Kraal, H. Witte, J. Sinninghe Damsté and D. RushSummaryRecently it was discovered that members of the marine anaerobic ammonium oxidizing (anammox) genus, ‘Ca. Scalindua spp.’, uniquely synthesize a stereoisomer of bacteriohopanetetrol (‘BHT-x’). The ratio of BHT-x over total BHT (ubiquitously synthesized by diverse aerobic bacteria) has been suggested as a proxy for water column anoxia. BHT-x hereby has the potential to act as a biomarker for anoxia as well as extend the sedimentary biomarker record of marine anammox. In this study, we have investigated the water column distributions of BHT-x and the BHT-x ratio in suspended particulate matter (SPM) samples at 15 stations along the large oxygen gradient in the Benguela Upwelling System (BUS). Distributions were compared to distributions of intact polar (IPL) ladderane phospholipids, ladderane fatty acids (FAs) and the presence of the Ca. Scalindua 16S rRNA gene reads. The similar distributions of BHT-x, ladderane FAs and the relative abundance of Ca. Scalindua 16S rRNA genes confirms the suitability of BHT-x as a biomarker for water column anammox in the sedimentary record of upwelling systems. Nevertheless, we suggest including the BHT-x ratio when interpreting anammox based on lipid biomarkers, as this study confirms that low abundance of BHT-x may not always reflect in situ water column anammox.
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ANALYSIS OF NON-DERIVATIZED BACTERIOHOPANEPOLYOLS USING UHPLC-HRMS2: A FURTHER STEP TOWARDS ENVIRONMENTAL LIPIDOMICS.
Authors E. Hopmans, N. Smit, R. Schwartz-Narbonne, J. Sinninghe Damsté and D. RushSummaryWe describe the analysis of non-derivatized bacteriohopanepolyols using UHPLC coupled to high resolution MS. We demonstrate the capabilities of the method by discussing the results of the analysis of a soil sample taken near an active terrestrial methane seep. We were able to identify 131 individual BHPS. We also identified tentatively identified several novel BHPs
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Organic Geochemistry and Source Rock Potential of the Bazhenov Black Shales form the West Siberian Basin, Russia
Authors L. Burnaz, A. Baniasad, A. Kalmykov, G. Kalmykov and R. LittkeSummaryThe West Siberian Basin (WSB) constitutes the largest petroleum province in Russia. The oil accumulations in the WSB are mainly sourced by the Upper Jurassic Bazhenov Formation (BF). This study aims to provide information on the geochemical and petrographic characteristics of a representative sample set of the siliceous BF black shales from the Southwest Ob region in the southwestern WSB. On 39 samples, comprehensive analyses and observations were performed, including total organic, inorganic carbon (TOC and TIC) and total sulfur content (TS) measurement, Rock-Eval pyrolysis, organic petrography and molecular geochemistry. The samples show excellent source rock potential and oil-prone source rock characteristics, mainly containing organic material that can be assigned to Type II kerogen. The black shales were deposited in a marine depositional environment with periodically anoxic conditions. The evaluation of maturity sensitive properties imply that the 39 samples are affected by varying degrees of thermal maturity covering the catagenesis stage from the onset to the end of the oil window.
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Evaluation of Anhydrosugars as a Molecular Proxy for Paleo-Fire Activity: A Case Study from Peloponnese, Greece
More LessSummaryAnhydrosugars like Levoglucosan (LVG) are produced upon incomplete combustion of cellulose, and can act as molecular markers for biomass burning. In this multi-proxy study from the Agios Floros wetland, Pelopponese, Greece, we found that wetter conditions - causing better organic matter preservation - was the dominant control on LVG concentrations. In contrast, the LVG profile was reciprocal to the microcharcoal record and to other proxy evidence for dryness, e.g. based on leaf wax hydrogen isotopes. We conclude that an approach using several proxies, both for fire, hydroclimate and vegetation change, is needed when aiming to reconstruct past biomass burning from wetland ecosystems with a strongly seasonal climate as in the Mediterranean. Our study also relates significant fire activity between 4400-2800 cal.yr BP to the Bronze Age period that saw intense human environmental interaction and climate change.
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Decoupling of temperature and hydroclimate in North China since late Miocene
More LessSummarywe separate the air temperature and hydrological records extending back six million years (Ma) on the basis of lipid biomarkers preserved in a terrestrial drill core (XA3 drill core) in North China, East Asia.
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Assessing the Impact of Magmatic Activity on Hydrocarbon Generation in the Namibe Basin (ANGOLA)
Authors E. Fiordalisi, B. Van Dongen, J. Moore, J. Hennissen, I. Sharp, R. Dixon and S. SchröderSummaryAssessing the impact of magmatic activity on source rock maturation and hydrocarbon generation is highly critical when evaluating the prospectivity of volcanically influenced sedimentary basins. An integrated organic geochemistry and petrographic study was conducted on a variety of bitumen samples and candidate source rocks from the Namibe Basin of Angola, which was affected by multiple magmatic events. Analyses suggest that multiple processes of hydrocarbon generation and emplacement took place, including locally forced thermal maturation of otherwise immature source rocks and source rock thermal maturation via conventional basin-scale burial processes. Imminent future analyses include vitrinite reflectivity and 1-D modelling to characterise the basin thermal regime and quantitatively assess the impact of magmatic activity on source rock maturation and hydrocarbon generation.
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Lipidomics of Environmental Microbial Communities
Authors S. Ding, N.J. Bale, E.C. Hopmans, L. Villanueva, M. Arts, S. Schouten and J.S. Sinninghe DamstéSummaryStructurally diverse, specialized lipids are crucial components of microbial membranes and other organelles and play essential roles in ecological functioning. The detection of such lipids in the environment can reveal not only the occurrence of specific microbes but also the physicochemical conditions to which they are adapted to. Traditionally, liquid chromatography coupled with mass spectrometry allowed for the detection of lipids based on chromatographic separation and individual peak identification, resulting in a limited data acquisition and targeted at certain lipid groups. Here, we explored a comprehensive profiling of microbial lipids throughout the water column of a marine euxinic basin (Black Sea) using ultra high-pressure liquid chromatography coupled with high-resolution tandem mass spectrometry (UHPLC-HRMS/MS). An information theory framework combined with molecular networking based on the similarity of the mass spectra of lipids enabled us to capture lipidomic diversity and specificity in the environment, identify novel lipids, differentiate microbial sources within a lipid group, and discover potential biomarkers for biogeochemical processes. The workflow presented here allows microbial ecologists and biogeochemists to process quickly and efficiently vast amounts of lipidome data to understand microbial lipids characteristics in ecosystems.
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PY-GC×GC-TOFMS: A POTENTIAL TOOL FOR THE MOLECULAR CHARACTERIZATION OF FOSSIL BIOPOLYMERS
Authors R. Umamaheswaran, S. Dutta and S. KumarSummaryIn recent years, there has been an increase in interest in the preservation of nitrogen-bearing biopolymers in organic remains from deep time, reflected by the increase in reports of such preservation. However, there has also been controversy regarding the veracity of these reports. Here, we propose a method to independently characterize the molecular structure of various biomacromolecules, by using pyrolysis comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (Py-GC×GC-TOFMS). We initially analyze G. Prisca, Tasmanites and fossil resin to demonstrate efficacy of this technique. We then analyze industry standards of chitin, collagen and fossil melanin to identify characteristic compound distributions and to distinguish between the three nitrogen-bearing biomacromolecules. We then apply the technique to an Eocene mammal bone.
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USING LOGGING DATA TO ESTABLISH A METHOD OF S1 CALCULATION AND EVALUATE OIL-BEARING PROPERTIES OF SOURCE ROCKS, SONGLIAO BASIN
By Z. XiaochangSummaryThe calculation model is established by using interval transit time and resistivity curves to calculate the rock pyrolysis parameter S1, so as to evaluate the oil-bearing property of source rocks. S1 of 168 wells are calculated by this method, and 71 wells of them have been measured S1 from core samples. Comparing the difference between the average value of calculated S1 and measured S1,it can be seen that the more samples measured S1 in a single well, the smaller the difference between the calculated S1 and the measured S1. By drawing several well-connected sections and S1 plans, the changing trend of oil-bearing property of source rocks in study area is definited, and the favorable oil-bearing areas are pointed out. This S1 calculation method is suitable for the oil-bearing evaluation of regional source rocks and has guiding significance for exploration.
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INFLUENCE OF CLASTIC MINERALS ON THE PHASE BEHAVIOR OF HYDROCARBON
More LessSummaryTo predict the phase state of the petroleum in these deep-buried reservoirs accurately would be of great benefit in further exploration and development. However, the influence of reservoir minerals on phase behaviors of crude oil in deeply buried reservoirs remains poorly understood. Here we report on our investigation of the influence of common siliceous minerals (quartz, feldspar, montmorillonite, illite) on the cracking and phase behavior of crude oil. We demonstrated that the common minerals found in clastic oil reservoirs have complicated influences on the thermal cracking behavior of crude oil. Further analyses showed that the PVT phase characteristics of the crude oil can also be related to the minerals present. Clay minerals, and especially montmorillonite, significantly change the dew point temperature and bubble point pressure. However, when Ro values exceed 2.0%, even when montmorillonite content reached 40 wt. %, the phase behavior of crude oil does not change significantly.
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INFLUENCE OF CARBONATE MINERALS ON THE PYROLYSIS BEHAVIOR OF HYDROCARBON
More LessSummaryThe knowledge of the influence of minerals on oil cracking behaviors will be benefit to the predicting of physical properties (such as density, viscosity and phase state) and chemical composition of petroleum. Though considerable amounts of carbonate reservoirs are dolostone reservoirs, the role of dolomite on the thermal evolution of hydrocarbons is still not well understood. To investigate the influence of dolomite, a series of laboratory simulation experiments of oil with various carbonate minerals, including calcite, magnesite, and dolomite were conducted and analysed here. This study demonstrate that two common carbonate minerals (calcite and dolomite) have different influences on the oil cracking behavior and PVT phase of oil in carbonate conditions. Calcite had limited influences on the thermal cracking behavior of crude oil, with slightly reduction of the yield of C6-13, while dolomite strongly affected the yield of C1-5, C6-13 and H2S. The presence of dolomite seems to promote the generation of H2S and the cracking of C1-5.
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Biomarker Signatures in Cretaceous Sediments of An Island Continent
Authors D. Niyolia, S. Dutta and B. SamantSummaryThe unique position of Indian plate during the Early Cretaceous draws our attention to study the paleofloral diversity on the Indian continent. An attempt has been made to investigate the distribution of biological markers of Early Cretaceous shale of Krishna Godavari (KG) Basin, Early Cretaceous coal and shale of Kutch Basin and Late Cretaceous shale from Deccan Intertrappean sediments. The terpenoid composition of Early Cretaceous samples of Kutch and KG Basin is represented by the significant occurrence of diterpenoids in both aliphatic and aromatic fractions. However, the Late Cretaceous sediments are dominated by angiosperm derived triterpenoids. Therefore, the present study clearly suggests that the angiosperms evolved in the island continent during the Late Cretaceous.
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Molecular and Isotope Composition of Biomarkers in Immature Oil Shale and its Liquid Pyrolysis Products (Open and Closed System)
Authors G. Gajica, A. Sajnovic, J. Schwarzbauer, A. Kostic, B. Jovancicevic and K. StojanovicSummaryThe molecular and isotopic composition of biomarkers in initial bitumen isolated from raw immature oil shale samples from the Lower Miocene Aleksinac Basin (Serbia) and liquid products (LPs) obtained by pyrolysis in open (OS) and closed systems (CS) are studied. The influence of pyrolysis type and variations of kerogen type on biomarkers composition and their isotopic signatures in LPs is determined.
The molecular composition of the LPs from the OS pyrolysis is very similar to those in initial bitumen, independently on kerogen type. The LPs from the CS pyrolysis have the distributions of biomarkers similar to those in crude oils generated in an early to main stage of “oil window“. The biomarker data suggests that mixed type I/II kerogen attained slightly higher maturity level by the CS pyrolysis than type I kerogen. The isotopic signatures of n-alkanes in LPs obtained by the OS pyrolysis are isotopically lighter than in initial bitumen, independently on kerogen type, whereas in liquid products from the CS they become heavier; showing more pronounced difference for type I kerogen. The results indicate that δ13C data should be used with caution in interpretation of samples having different maturity and particularly of LPs obtained by different system pyrolysis.
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Hydrocarbons in Intertidal Deposits of the Norwegian and Russian Coast of the Barents Sea
Authors A. Kursheva, I. Morgunova, V. Petrova, I. Litvinenko, G. Batova, A. Maltseva, E. Golikova and P. RenaudSummaryThe complex study of the organic matter (OM) and HC molecular markers in sediments and soils of the Arctic littoral is an important step to the environment protection. The study of polycyclic aromatic HCs (PAHs) is of particular interest due to their toxicity and high content in the main anthropogenic pollutants (oil, fuels, combustion products etc.).
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Organic Matter in Bottom Sediments of the Shelf Part of the Laptev Sea as an Indicator of Sedimentation (Expedition 2018)
Authors I. Litvinenko, A. Kursheva, V. Petrova, G. Batova, I. Morgunova and E. GusevSummaryThe main idea was to investigate the composition of hydrocarbon (HC) molecular markers, as indicators of the origin of sedimentary material. The object of the study is bottom sediments collected from latitudinal transects stretching along the outer edge of the shelf and the upper continental slope of the Laptev Sea. Sampling was made during the research cruise of FSBI VNIIOkeangeologia in 2018 (R/V Ivan Petrov). The molecular composition of the DOM indicates a significant input of terrigenous components of diagenetic maturity degree to the sediments of the region. Moreover, the input of molecular markers characteristic for the bacterial activity (possibly methanotrophic) is detected in some sediments (n-C16 and n-C18 predominate in composition of the lower molecular weight n-alkanes; the tricyclic terpanes ratio (2(C19+С20)/(C23+С24+C25+С26) < 1). The inflow of the reduced Atlantic waters with the along-slope currents and the processes of bottom and coastal abrasion determine the contribution of the transformed marine DOM to the sediments of continental margin.
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STABLE ISOTOPE SIGNATURES FROM SUBSTRATE UTILIZATION BY DIFFERENT FUNGAL ECOTYPES VIA A DUAL-SIP APPROACH
Authors S. Jabinski, W. De Melo Rangel, F. Lorenz and T.B. MeadorSummaryEach year, roughly one-sixth of atmospheric carbon (115 Pg C) is cycled through terrestrial vegetation, channeled into the soils below, and respired back to CO2 ( IPCC, 2007 ). However, predicting the reactivity and CO2 buffering capacity of soil systems and thus the carbon-climate feedback in terrestrial ecosystems is limited by poor understanding of the accessibility and turnover of “recalcitrant” organic matter in soils ( Lehmann & Kleber, 2015 ). As major decomposers in soil ecosystems, fungi are among the few organisms on the planet that can feed on chemically stable forms of organic C ( Šnajdr et al., 2011 ; Kirk & Farrell, 1987 ) but are also known to directly access recently produced plant photosynthate ( Högberg et al., 2001 ). This study improves quantification of substrate utilization by different fungal ecotypes in order to help define the rates and controls of fungal production and the cycling of soil organic matter.
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A Reappraisal of Hydrocarbons Generation and Destruction in the Petroleum Systems of Southern Aquitaine (France).
Authors R. Michels, D. Rallakis, A. Elias-Bahnan, G. Barré, J. Pironon, S. Calassou and E.C. GaucherSummarySedimentary basins in compressive settings have often complex geological histories and features. Therefore, they present a real challenge in oil and gas exploration. Recent revision of the geodynamic evolution of the North Pyrenees mountain range (France) lead to consider the effects of intense heat flow during the rifting phase prior to compression. We investigated the consequences of this previously unrecognized heating episode on the evolution of the fluids within the petroleum systems on the southern rim of the north Pyrenean foreland basin (Aquitaine basin, France). Taking into account the geodynamic frame, fluids geochemistry was investigated using fluid inclusions from major reservoirs, reservoir gas and oils geochemistry, maturation of the source-rocks through basin modelling and artificial maturation, multiple sulfur isotopes analysis. Results permit to reconsider the maturation history of source rocks, conditions and impact of TSR, secondary migration and reservoir filling as well as to understand the distribution of gas vs petroleum and sourness of fields.
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Molecular Characterization and Geochemical Significance of No Compounds in Saline Lacustrine Source Rock
More LessSummaryNO compounds refer to compounds containing N and O heteroatoms, which are widely present in geological bodies. NO compounds contain rich geological and geochemical information and they are of great significance for petroleum exploration. High-resolution mass spectrometry (FT-ICR MS) is used to analyze the composition and distribution characteristics of nitrogen and oxygen heteroatom compounds in the source rocks of saline lacustrine facies. The results show that a total of 12 types of NO heteroatom compounds were detected in the analyzed samples, including N1, N1O1, N1O2, N1O3, N1S1, N1S2, N2O1, O1, O2, O3, O3S1, O4, mainly O2 and O3, followed by N1 and N1O1; The N1 category is dominated by DBE=9, 12, 15 and 18. The distribution of O2 compounds is controlled by biogenic sources and has great potential in predicting the original parent material. N1, O2, and N1O1 compounds are all influenced by maturity with polarization performance. NO compounds are also affected by the deposition environment. It is observed that there are abundant O2 and N1O1 compounds in the saline lacustrine facies source rocks. The research results can shed light for the research of genetic mechanism of oil and gas
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Biomarker Data Demonstrate that Perturbation of the Terrestrial Methane Cycle is a Common Feature of Hyperthermals
Authors D. Naafs, A. Ebinghaus, D.W. Jolley and D.B. KempSummaryNovel biomarker data provide new insights into the impact of hyper thermals on key biogeochemical cycles. We show that the Dan-C2 hyper thermal led to a major perturbation in a terrestrial lake system, including an intensified terrestrial methane cycle. Our data for the first time confirm the hypothesis that the perturbation of the terrestrial methane cycle was a common positive feedback mechanism for hyperthermals during the Paleogene.
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Global Temperature and pH Calibrations Based on Bacterial 3-HYDROXY Fatty Acids in Soils
Authors P. Véquaud, S. Derenne, A. Thibault, C. Anquetil, G. Bonanomi, S. Collin, S. Contreras, A. Nottingham, P. Sabatier, N. Salinas, W.P. Scott, J.P. Werne and A. HuguetSummary3-hydroxy fatty acids (3-OH FA), produced by Gram-negative bacteria, were recently proposed as promising temperature and pH proxies in terrestrial settings. Nevertheless, the existing correlations between pH/temperature and indices derived from 3-OH FA distribution are based on a small soil dataset (ca. 70 samples) only applicable regionally. The aim of this study was to investigate the applicability of 3-OH FAs as mean annual air temperature (MAAT) and pH proxies at the global level using an extended dataset of 168 surficial soils from 8 globally distributed elevational transects. Strong linear relationships between 3-OH FA-derived indices and MAAT/pH could only be obtained locally, for some of the individual transects. In addition to linear regressions, non-parametric, machine learning models were used to improve the global relationships between 3-OH FA distribution and MAAT/pH. Strong global correlations between MAAT/pH and 3-OH FA relative abundances were obtained by using multiple linear regression, k-NN and random forest models.
The applicability of the k-NN and random forest models for paleotemperature reconstruction was tested with the MAAT record from a Chinese speleothem. The calibration based on the random forest model appeared to be the most robust. These results demonstrate the potential of 3-OH FAs as paleoproxies in terrestrial settings.
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EVALUATION OF ERODED MESOZOIC FORMATIONS IN NORTHERN ALSACE (FRANCE) USING ORGANIC GEOCHEMISTRY AND BASIN THERMAL MODELLING
Authors L. Tchang-tchong, P. Faure-Catteloin, E. Gaucher, C. Lorgeoux and R. MichelsSummaryIn the URG, the terminal Jurassic and Cretaceous formations are missing. It remains uncertain whether their absence is related to a sedimentary hiatus or a period of erosion. The geochemical analyses of the Jurassic outcrops of Pechelbronn area show that the Mesozoic formations are immature. It suggests that these deposits were not sufficiently buried before the Cretaceous. By using molecular markers, vitrinite reflectance, kinetic properties of source rocks, artificial maturation and 1D thermal basin models, we can estimate a maximum paleo-burial, evaluate the heat flux and simulate the oil generation.
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HYDROCARBON MASS BALANCE CALCULATIONS IN PETROLEUM SYSTEMS EXPERIENCING THERMOCHEMICAL SULFATE REDUCTION (TSR)
Authors D. Rallakis, R. Michels, A. Elias-Bahnan, G. Barré, J. Pironon, C. Lorgeoux, S. Calassou and E.C. GaucherSummaryThe quantitative assessment of thermochemical sulfate reduction (TSR) in petroleum systems is to date not entirely understood. Since the term TSR was first established in the 1970’s, many equations have been proposed to explain the kinetics of the reaction. Each reaction returns very often different numerical results, which reveals the degree of uncertainty. The area of study is located in SW France, in the South Aquitaine Basin where the giant sour dry gas (up to 18 vol% H2S) field of Lacq is located. The present study evaluates three TSR net equations taken from literature ( Orr, 1974 ; Goldhaber and Orr, 1995 ; Worden et al., 1995 ; Machel, 2001 ; Mougin et al., 2007 ; Liu et al., 2013 ) by applying them to mass balance calculations on the Lacq petroleum system. Objective is to compare constency of the calculated masss balance with the geological situation of the system.
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Investigating water depth influence on organic paleotemperature proxies from sedimentary archives
Authors D. Varma, K. Hättig, M. Van der Meer, G. Reichart and S. SchoutenSummaryThe TEX₈₆ has been widely used as a paleothermometer to reconstruct past water temperatures. A recent study had suggested a re-calibration of TEX₈₆ to deep sub-surface ocean temperatures, far deeper than previously assumed for TEX₈₆ signals. Such a calibration would imply a potential influence of water depth on TEX₈₆ values from sites with widely varying water depths. Here we investigate the potential impact of water depth on organic temperature proxies by analyzing sedimentary signals (TEX₈₆ and UK’₃₇) from two geographically proximal sites, but from different water depths, encompassing several glacial-interglacial cycles in the Late Quaternary. We observe that TEX₈₆ temperature records from nearby shallow and deep site show no significant difference and yield similar temperature estimates as the UK’₃₇.
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Evidence of Human Controlled Fires at Acheulean Site of Valdocarros Ii (Spain, Mis 8/7): Application of Organic Geochemistry
More LessSummaryIn this study, we focus on the site Valdocarros II, in the Jarama river valley (Madrid) in central Spain, despite being an open-air site, we identify anthropogenic evidence of hearts or burning by-products via a multi-proxy approach. The site of Valdocarros II (Madrid, Spain) is located in the Jarama basin with evidence of human occupancy dating to ca. 240 ka (transition of Marine Isotope Stage 8/7). The site is one of the very few Middle Pleistocene localities to have documented associations of bones and acheulean stone tools in different levels. Therefore, in this study, we examined the distribution of multiple compound classes (n-alkanes, n-alcohols, n-alkanoic acids and polycyclic aromatic hydrocarbons (PAHs) of a total of 28 samples excavated around 11 fire hearths. Moreover, samples from Hearth-1 showed the presence of 18-Norabieta-8,11,13-trie4,5 that indicate conifers wood burning, as well most samples show abundances of 2-ring, 3-ring methyl-, and di-methyl PAHs that are indicators of wood burning. Our results add to our still-limited knowledge about the controlled use of fire in the Upper Palaeolithic and contribute to ongoing debates on the behavioral complexity of the human groups with acheulean technology in Europe.
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Total Organic Carbon Evaluation of Heterogeneous Coaly Facies Using Well Logs Data, Carboniferous Lorraine Basin (France).
Authors S. Allouti, R. Michels, A. Izart, M. Mombo-Mouketo, F. Malartre, D. Bartier, Y. Géraud and F. NassifSummaryContinental fluvio-lacustrine coal bearing strata in the Carboniferous of the Saar-Lorraine basin are particularly heterogenous in their distribution. This renders source-rock volume evaluation difficult. This study focuses on the TOC determination along well-log. When cores are available, sample picking and TOC measurements through lab methods is not satisfactory since it generates discontinuous data sets. An alternative method is to use continuous well-log data and calculate TOC using DeltalogR or Carbolog methods. TOC assessment is quite accurate for sandy facies but underestimates values for coaly shales, shaly coals and coals seams. Objectives of this presentation will be to explain why TOC are underestimated for shales and coal seams, how to correct the calculated values and how this impacts the source-rock volumes estimates in these unconventional reservoirs.
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Hydrocarbon Molecular Markers in Bottom Sediments of the Focus Fluid Discharge Zones of the Lake Baikal
Authors I. Morgunova, A. Krylov, P. Semenov, V. Petrova, A. Kursheva, I. Litvinenko, S. Malyshev and O. KhlystovSummaryThe main idea of this study was to identify the background and anomaly distribution of hydrocarbon molecular markers in sediments of the lake Baikal and to define organic matter sources and specificity of its formation under the diagenetic and fluid discharge conditions. The study has shown that processes of hydrocarbon biodegradation are widespread in sediments of the oil discharge zone of the lake Baikal, but are not characteristic for the areas of mud volcanism and hydrothermal venting. The composition of hydrocarbon molecular markers in sediments near the mud volcano and hydrothermal vent area testify to the active growth of microbial biomass that uses methane and low molecular weight hydrocarbons coming from the deep as a main carbon source.
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