Nicolaj Mahlstedt - Academia.edu (original) (raw)
Papers by Nicolaj Mahlstedt
Geologic background information, Total organic carbon (TOC), Vitrinite Reflectance (VRr), Rock-Ev... more Geologic background information, Total organic carbon (TOC), Vitrinite Reflectance (VRr), Rock-Eval S2, gas sorption data acquired using petrophysical methods and Tvap GC-FID, and kerogen aromaticity assessed using open-system pyrolysis GC-FID
Hydrocarbons, Oils and Lipids: Diversity, Origin, Chemistry and Fate, 2018
Journal of Petroleum Science and Engineering, 2021
Abstract The Early to Late Miocene Belait Formation in Brunei-Muara district has been investigate... more Abstract The Early to Late Miocene Belait Formation in Brunei-Muara district has been investigated using the PhaseKinetic approach for compositional petroleum generation kinetics. The source rock characteristics of the selected coal and coaly shale samples indicate kerogen type III-II and type III with moderate HI recorded in the range of 156–258 mg HC/g TOC. The Rock Eval pyrolysis data also show immature organic matter with maximum recorded Tmax values of 415 °C. Pyrolysis gas chromatography (PyGC) reflects that the source rocks generated petroleum grading from paraffinic-naphthenic-aromatic (P–N-A) high wax to gas and condensate, which can be interpreted as heterogeneous kerogen derived from terrigenous higher land plant material. The main activation energies range of two selected coal samples (S24 and S27) are located at 49–52 kcal/mol accounting each for only 15% of the total bulk reaction. Assuming a 3 °C/My geologic heating rate, calculated onset temperatures for the generated hydrocarbon at transformation ration, TR = 10% were 105–120 °C for the two samples. The end of hydrocarbon generation at approximately TR = 95% is expected to occur at temperatures around 170 °C and above. MSSV pyrolysis gas chromatography affirms the existence of high wax paraffinic kerogen type–III–II with some marine input for one end member sample (S24). The 4-component compositional kinetic model indicates that the maximum generation of different petroleum components of sample S24 is predicted at lower values of temperature and vitrinite reflectance if compared with sample S27. The other end member of sample (S27) is more typically humic coal-like with type-III kerogen generating mostly gas and condensate.
International Journal of Coal Geology, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Organic Geochemistry, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
International Journal of Coal Geology, 2019
Comparison of single-and multi-ramp bulk kinetics for a natural maturity series of Westphalian co... more Comparison of single-and multi-ramp bulk kinetics for a natural maturity series of Westphalian coals: Implications for modelling petroleum generation,
Goldschmidt2022 abstracts
International Journal of Coal Geology
International Journal of Hydrogen Energy
We report on Precambrian microfossils from igneous rocks of the Volyn pegmatite district, associa... more We report on Precambrian microfossils from igneous rocks of the Volyn pegmatite district, associated with the Paleoproterozoic Korosten pluton, northwestern Ukraine. The fossils were recovered from meter-sized miarolitic cavities and show a well-preserved 3D morphology, mostly filamentous but with a large variety of types and also in irregular, flaky shapes reminiscent of former biofilms, as well as rare spherical objects. Based on literature data, pyrolysis experiments, and reflected light microscopy results, the organic matter (OM) is characterized as (oxy-)kerite. Further investigations with microscopic techniques, including scanning and transmission electron microscopy, and electron microprobe analysis show that fossilization likely occurred during a hydrothermal, post-pegmatitic event by silicification dominantly in the outermost 1-2 µm of the microfossils. The hydrothermal fluid, derived from the pegmatitic environment, was enriched in SiF 4 , Al, Ca, Na, K, Cl, and S. The OM shows O enrichment in which N and S content is low, indicating simultaneous N and S loss during anaerobic oxidation. Mineralization with Al silicates starts at the rim of the microfossils, continuing in its outer parts into identifiable encrustations and intergrowths of clay minerals, feldspar, Ca sulfate, Ca phosphate, Fe sulfide, and fluorite. Breccias, formed during collapse of some the miarolitic cavities, contain decaying OM, which released high concentrations of dissolved NH 4 + , responsible for the late-stage formation of tobelite-rich muscovite and buddingtonite. The age of the fossils can be restricted to the time between the pegmatite formation, at ∼ 1.760 Ga, and the breccia formation at ∼ 1.49 Ga. As the geological environment for the growth of the microorganisms and fossilization, we assume a geyser system in which the essential biological components C, N, S, and P for growth of the organisms in the miarolitic cavities were derived from microorganisms at the surface. Fossilization was induced by magmatic SiF 4-rich fluids. The Volyn occurrence is a distinct and uncommon example of Precambrian fossils, and the results underline the importance of cavities in granitic rocks as a possible habitat for microorganisms preserved in the deep biosphere.
Earth-Science Reviews, 2021
The organic carbon-and uranium-rich, marine Alum Shale Formation Formation in northwestern Europe... more The organic carbon-and uranium-rich, marine Alum Shale Formation Formation in northwestern Europe (Middle Cambrian, Miaolingian to Early Ordovician) was deposited in the Baltic Basin and surrounding areas. It is a proven source rock for conventional oil either in sandstones of Cambrian age or Ordovician and Silurian carbonates, and also contains a potential for shale oil and for biogenic or thermogenic shale gas. compared to other well-studied shale formations. Based on brittleness estimates, the Alum Shale Formation may be regarded as an unconventional reservoir rock of medium quality from the mechanical point of view.
AAPG Bulletin, 2021
In the Upper Cretaceous Niobrara Formation shale oil play, considerable oil fractions are produce... more In the Upper Cretaceous Niobrara Formation shale oil play, considerable oil fractions are produced directly from C14+ bitumen-in-place, e.g., extractable organic matter (EOM). This report provides new insights on the geochemistry and producibility of C14+ bitumen by integrating the full process of generation, retention, conversion, expulsion, and production, as a whole, in the Niobrara shale oil system. Hydrocarbons are found not to be generated primarily from kerogen, but rather from the secondary conversion of polar compounds. Maturation is essentially the underlying driving force that determines the geochemistry of C14+ bitumen in source rocks. However, the in-situ cracking of C14+ bitumen does not occur in chalk reservoirs at the maturity stage investigated (430–465 °C TmaxE). Instead of maturation, the geochemistry of C14+ bitumen present in reservoirs is principally determined by migration and associated fractionation. The intraformational migration has fractionated the generated oil into a higher saturated fluid and, therefore, C14+ bitumen accumulated in chalk reservoirs is more producible than that retained in source rocks. In comparison, the bulk fractionation effect associated with production is not as pronounced as that of expulsion. Therefore, the bulk compositions of chalk bitumen strongly resemble those of crude oils. Among the least mobile nitrogen-, sulfur-, and oxygen- containing (NSO) compounds, N1 species are nevertheless partitioned into crude oils during production, and the molecular weight exhibits a less apparent effect on their producibility than chemical affinity, i.e., aromaticity and aliphaticity. Accordingly, a relative enrichment of C5+ heavier carbazoles into crude oils rather than the lighter C1-5 carbazoles was documented.
30th International Meeting on Organic Geochemistry (IMOG 2021), 2021
Summary Open-system pyrolysates of fourty-three immature source rock and coal samples covering al... more Summary Open-system pyrolysates of fourty-three immature source rock and coal samples covering all depositional environments and geological ages were prepared and analysed using Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR MS) in connection with an electrospray source run in negative-ion mode to asses the fraction of acidic NSO compounds. The aim was to establish proxies based on the NSO inventory of pyrolysates for kerogen and petroleum type organofacies typing. The main result is that different depositional environments/ organofacies can be characterized using bulk NSO elemental and compound class distributions in combination with DBE class and Carbon number distributions. The feasability of the approach is demonstrated by Principal Components Analysis, whereas the geochemical background of the used loadings is discussed in detail in the paper/presentation.
29th International Meeting on Organic Geochemistry, 2019
Journal of Petroleum Science and Engineering, 2019
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Geologic background information, Total organic carbon (TOC), Vitrinite Reflectance (VRr), Rock-Ev... more Geologic background information, Total organic carbon (TOC), Vitrinite Reflectance (VRr), Rock-Eval S2, gas sorption data acquired using petrophysical methods and Tvap GC-FID, and kerogen aromaticity assessed using open-system pyrolysis GC-FID
Hydrocarbons, Oils and Lipids: Diversity, Origin, Chemistry and Fate, 2018
Journal of Petroleum Science and Engineering, 2021
Abstract The Early to Late Miocene Belait Formation in Brunei-Muara district has been investigate... more Abstract The Early to Late Miocene Belait Formation in Brunei-Muara district has been investigated using the PhaseKinetic approach for compositional petroleum generation kinetics. The source rock characteristics of the selected coal and coaly shale samples indicate kerogen type III-II and type III with moderate HI recorded in the range of 156–258 mg HC/g TOC. The Rock Eval pyrolysis data also show immature organic matter with maximum recorded Tmax values of 415 °C. Pyrolysis gas chromatography (PyGC) reflects that the source rocks generated petroleum grading from paraffinic-naphthenic-aromatic (P–N-A) high wax to gas and condensate, which can be interpreted as heterogeneous kerogen derived from terrigenous higher land plant material. The main activation energies range of two selected coal samples (S24 and S27) are located at 49–52 kcal/mol accounting each for only 15% of the total bulk reaction. Assuming a 3 °C/My geologic heating rate, calculated onset temperatures for the generated hydrocarbon at transformation ration, TR = 10% were 105–120 °C for the two samples. The end of hydrocarbon generation at approximately TR = 95% is expected to occur at temperatures around 170 °C and above. MSSV pyrolysis gas chromatography affirms the existence of high wax paraffinic kerogen type–III–II with some marine input for one end member sample (S24). The 4-component compositional kinetic model indicates that the maximum generation of different petroleum components of sample S24 is predicted at lower values of temperature and vitrinite reflectance if compared with sample S27. The other end member of sample (S27) is more typically humic coal-like with type-III kerogen generating mostly gas and condensate.
International Journal of Coal Geology, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Organic Geochemistry, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
International Journal of Coal Geology, 2019
Comparison of single-and multi-ramp bulk kinetics for a natural maturity series of Westphalian co... more Comparison of single-and multi-ramp bulk kinetics for a natural maturity series of Westphalian coals: Implications for modelling petroleum generation,
Goldschmidt2022 abstracts
International Journal of Coal Geology
International Journal of Hydrogen Energy
We report on Precambrian microfossils from igneous rocks of the Volyn pegmatite district, associa... more We report on Precambrian microfossils from igneous rocks of the Volyn pegmatite district, associated with the Paleoproterozoic Korosten pluton, northwestern Ukraine. The fossils were recovered from meter-sized miarolitic cavities and show a well-preserved 3D morphology, mostly filamentous but with a large variety of types and also in irregular, flaky shapes reminiscent of former biofilms, as well as rare spherical objects. Based on literature data, pyrolysis experiments, and reflected light microscopy results, the organic matter (OM) is characterized as (oxy-)kerite. Further investigations with microscopic techniques, including scanning and transmission electron microscopy, and electron microprobe analysis show that fossilization likely occurred during a hydrothermal, post-pegmatitic event by silicification dominantly in the outermost 1-2 µm of the microfossils. The hydrothermal fluid, derived from the pegmatitic environment, was enriched in SiF 4 , Al, Ca, Na, K, Cl, and S. The OM shows O enrichment in which N and S content is low, indicating simultaneous N and S loss during anaerobic oxidation. Mineralization with Al silicates starts at the rim of the microfossils, continuing in its outer parts into identifiable encrustations and intergrowths of clay minerals, feldspar, Ca sulfate, Ca phosphate, Fe sulfide, and fluorite. Breccias, formed during collapse of some the miarolitic cavities, contain decaying OM, which released high concentrations of dissolved NH 4 + , responsible for the late-stage formation of tobelite-rich muscovite and buddingtonite. The age of the fossils can be restricted to the time between the pegmatite formation, at ∼ 1.760 Ga, and the breccia formation at ∼ 1.49 Ga. As the geological environment for the growth of the microorganisms and fossilization, we assume a geyser system in which the essential biological components C, N, S, and P for growth of the organisms in the miarolitic cavities were derived from microorganisms at the surface. Fossilization was induced by magmatic SiF 4-rich fluids. The Volyn occurrence is a distinct and uncommon example of Precambrian fossils, and the results underline the importance of cavities in granitic rocks as a possible habitat for microorganisms preserved in the deep biosphere.
Earth-Science Reviews, 2021
The organic carbon-and uranium-rich, marine Alum Shale Formation Formation in northwestern Europe... more The organic carbon-and uranium-rich, marine Alum Shale Formation Formation in northwestern Europe (Middle Cambrian, Miaolingian to Early Ordovician) was deposited in the Baltic Basin and surrounding areas. It is a proven source rock for conventional oil either in sandstones of Cambrian age or Ordovician and Silurian carbonates, and also contains a potential for shale oil and for biogenic or thermogenic shale gas. compared to other well-studied shale formations. Based on brittleness estimates, the Alum Shale Formation may be regarded as an unconventional reservoir rock of medium quality from the mechanical point of view.
AAPG Bulletin, 2021
In the Upper Cretaceous Niobrara Formation shale oil play, considerable oil fractions are produce... more In the Upper Cretaceous Niobrara Formation shale oil play, considerable oil fractions are produced directly from C14+ bitumen-in-place, e.g., extractable organic matter (EOM). This report provides new insights on the geochemistry and producibility of C14+ bitumen by integrating the full process of generation, retention, conversion, expulsion, and production, as a whole, in the Niobrara shale oil system. Hydrocarbons are found not to be generated primarily from kerogen, but rather from the secondary conversion of polar compounds. Maturation is essentially the underlying driving force that determines the geochemistry of C14+ bitumen in source rocks. However, the in-situ cracking of C14+ bitumen does not occur in chalk reservoirs at the maturity stage investigated (430–465 °C TmaxE). Instead of maturation, the geochemistry of C14+ bitumen present in reservoirs is principally determined by migration and associated fractionation. The intraformational migration has fractionated the generated oil into a higher saturated fluid and, therefore, C14+ bitumen accumulated in chalk reservoirs is more producible than that retained in source rocks. In comparison, the bulk fractionation effect associated with production is not as pronounced as that of expulsion. Therefore, the bulk compositions of chalk bitumen strongly resemble those of crude oils. Among the least mobile nitrogen-, sulfur-, and oxygen- containing (NSO) compounds, N1 species are nevertheless partitioned into crude oils during production, and the molecular weight exhibits a less apparent effect on their producibility than chemical affinity, i.e., aromaticity and aliphaticity. Accordingly, a relative enrichment of C5+ heavier carbazoles into crude oils rather than the lighter C1-5 carbazoles was documented.
30th International Meeting on Organic Geochemistry (IMOG 2021), 2021
Summary Open-system pyrolysates of fourty-three immature source rock and coal samples covering al... more Summary Open-system pyrolysates of fourty-three immature source rock and coal samples covering all depositional environments and geological ages were prepared and analysed using Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR MS) in connection with an electrospray source run in negative-ion mode to asses the fraction of acidic NSO compounds. The aim was to establish proxies based on the NSO inventory of pyrolysates for kerogen and petroleum type organofacies typing. The main result is that different depositional environments/ organofacies can be characterized using bulk NSO elemental and compound class distributions in combination with DBE class and Carbon number distributions. The feasability of the approach is demonstrated by Principal Components Analysis, whereas the geochemical background of the used loadings is discussed in detail in the paper/presentation.
29th International Meeting on Organic Geochemistry, 2019
Journal of Petroleum Science and Engineering, 2019
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.