Improved Kerogen Models for Determining Thermal Maturity and Hydrocarbon Potential of Shale

Agrawal, Vikas

doi:10.1038/s41598-018-35560-8

Cited by 24 publications

(14 citation statements)

References 42 publications

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“…Kerogen is formed from biologically derived organic matter by diagenetic processes in the first few hundred meters of burial, and it is converted to bitumen and then into oil and gas during the process of catagenesis, the thermal degradation stage of petroleum formation. , During this process, the increase in temperature and pressure results in a progressive alteration of its chemical structure, which undergoes successive condensation reactions, leading to a gradual increase in the sp 2 /sp 3 carbon hybridization ratio. − At high thermal maturity, the kerogen structure condenses to mainly aromatic units in sp 2 -hybridized graphitic structures. The quality and amount of hydrocarbon generated are controlled by the concentration, type, and thermal maturity of the kerogen. − In this respect, many efforts have been devoted to kerogen isolation and to the characterization of its chemical structure and evolution during thermal maturation, aiming at a better prediction of the potential for oil and gas production.…”

Section: Introductionmentioning

confidence: 99%

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Combined High-Resolution Solid-State ¹H/¹³C NMR Spectroscopy and ¹H NMR Relaxometry for the Characterization of Kerogen Thermal Maturation

et al. 2020

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A key factor for the petroleum potential of source rock is the degree of chemical and physical structure evolution of its kerogen fraction through a range of maturation processes. In this study, various high-field, solid-state NMR methods have been applied to a series of kerogen isolates (type I) over a defined maturity range (vitrinite reflectance R 0 from 0.98 to 1.86%). Results obtained from 13C MAS NMR show that the sp2/sp3-hybridized carbon ratio of kerogen, here defined as the aromatic/aliphatic ratio, increases with increasing maturity. 1H MAS NMR spectra contain partly overlapping aliphatic and aromatic resonances with distinct transverse relaxation behavior. In Hahn-echo experiments, the aromatic signal decays more slowly than the aliphatic signal, indicating that for these systems, transverse 1H relaxation is rather controlled by local distances between hydrogen atoms than by molecular mobility. Similar relaxation differences are also found in static (nonspinning) 1H Hahn-echo NMR experiments, here used to discriminate between phases with different proton mobilities and/or densities in the kerogen samples and, ultimately, between aromatic and aliphatic fractions. The distributions of the static transverse relaxation time (T 2), extracted from the Hahn-echo decays, are characterized by a short-T 2 peak (∼10 μs) and a long-T 2 peak (∼100 μs). The ratio between these two peaks correlates well with the aliphatic-to-aromatic signal intensity ratios in MAS NMR spectra of the corresponding kerogen samples, suggesting that a net decrease in kerogen proton densityoccurring during maturationis also reflected by 1H NMR relaxation. For the investigated kerogen isolates, the long-T 2 peak in the T 2 distribution can be considered an indicator of aromatic content, which can be directly detected by measuring 1H T 2 relaxation.

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Section: Introductionmentioning

confidence: 99%

“…However, vitrinite materials are of terrestrial origin and, therefore, are generally rare or absent in type I and type II kerogens and are present as a major maceral only in type III kerogen . Errors are involved in measuring reflectance on vitrinite, as this subcomponent may not be present in kerogen.…”

Section: Introductionmentioning

confidence: 99%

Combined High-Resolution Solid-State ¹H/¹³C NMR Spectroscopy and ¹H NMR Relaxometry for the Characterization of Kerogen Thermal Maturation

et al. 2020

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“…However, the exact point at which an HLM/ITM transitions to a KLM/MTM (or even at which humics are considered kerogens) on a structural/molecular basis is not well defined within the primary literature outside of operational definitions based on solubility (Vandenbroucke & Largeau 2007). During carbonization, the HLMs/ITMs of preserved cells and tissues undergo extensive conversion of aliphatic sp 3 orbitals to lower energy/more stable sp 2 orbitals of aromatic alkenes (Agrawal & Sharma 2018;Rouzaud et al 2015;Wei et al 2005). Additionally, heteroatoms are removed from the polymer structure, resulting in a disorganized system of interconnected aromatic rings (polyaromatic hydrocarbons, i.e., KLMs/MTMs) (Agrawal & Sharma 2018;Briggs & Summons 2014;Oberlin 1984;Rouzaud et al 2015;Wei et al 2005), thus reducing structural variation within the macromolecules.…”

Section: Carbonizationmentioning

confidence: 99%

A Chemical Framework for the Preservation of Fossil Vertebrate Cells and Soft Tissues

Anderson

2022

Preprint

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Reports of preserved cells and other soft tissues in pre-Pleistocene vertebrates, including dinosaurs, have been met with controversy within the field of vertebrate paleontology. To explain such reports, Schweitzer et al. ( 2014) hypothesized that iron-mediated radical crosslinking preserves ancient soft tissues in a manner somewhat analogous to histological tissue fixation. In 2018, Wiemann et al. proposed a second hypothesis that these soft tissues were preserved as advanced glycation/lipoxidation end products (AGEs/ALEs). The biogeochemistry underlying these hypotheses, however, remains poorly described for fossil vertebrates.This review posits a novel chemical framework describing the persistence of biological "soft" tissues into deep time. The prior iron-mediated radical crosslinking and AGE/ALE mechanisms are re-described in context of established chemistry from a diversity of scientific fields. Significantly, this framework demonstrates the hypotheses presented by Schweitzer et al. (2014) and Wiemann et al. (2018) are, in many cases, subsequent steps of a single, unified reaction mechanism, and not separate hypotheses. Knowledge of the chemical mechanisms underlying vertebrate soft tissue preservation has direct implications for molecular paleontology and archeology, including efforts at molecular sequence recovery within the ancient DNA and paleoproteomic communities. Such implications that are immediately apparent from examining the chemical framework are discussed. I.

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“…Apart from TOC, the qual ity of shale source rock might be de ter mined by its type of kerogen and orig i nal hy dro gen in dex (Jarvie et al, 2007;Jarvie, 2012a, b;Hackley and Cardott, 2016). Ther mal ma tu rity de fines the po ten tial of shale to gen er ate hy dro carbons, the type of hy dro car bons sat u rat ing the shale res er voir, and the risk of over matu ration (Hill et al, 2007;Ber nard and Horsfield, 2014;Agrawal and Sharma, 2018). In creas ing thermal ma tu rity re sults also in a rise of sec ond ary, or ganic po rosity (Passey et al, 2010;Jarvie, 2012a, b;Hackley and Cardott, 2016).…”

Section: Characteristics Of the Lower Paleozoic Oil And Gas Shalementioning

confidence: 99%

Lower Paleozoic oil and gas shale in the Baltic-Podlasie-Lublin Basin (central and eastern Europe) – a review

Poprawa¹

2020

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In the Bal tic-Podlasie-Lublin Ba sin, four po ten tial lower Pa leo zoic shale res er voirs are iden ti fied: the Piaśnica, Sasino and Jantar for ma tions, as well as the Mingajny shale. These units were diachronously de pos ited dur ing the starved stages of Cal edo nian foredeep ba sin de vel op ment, in the course of ris ing or high eustatic sea level. Across most of the ba sin, the shale for ma tions ana lysed are sat u rated with light oil and con den sate, and they are bur ied to depths of 2300-3500 m. The shale res er voirs reach the wet gas win dow at burial depths of 2800-4000 m, while dry gas ac cu mu la tions oc cur at depths ex ceed ing 3500-5000 m, ex cept in the Biłgoraj-Narol Zone. The shale ana lysed might be gen er ally clas si fied as a mod erate to low qual ity, and lo cally high qual ity, un con ven tional res er voir. Within the shale net pay zones, the av er age TOC content is 2-5 wt.% TOC. The ex cep tions are the Piaśnica For ma tion, for which this is 5-12 wt.%, and the Mingajny shale, which is TOC-lean (1.4-1.7 wt.%). The thick ness of the shale net pay in ter vals in the most fa vour able lo ca tions, mainly on the Łeba Elevation, gen er ally reaches 20 m, and lo cally ex ceeds 35 m. The shale res er voirs are sat u rated with hy dro carbons of good qual ity. Their per me abil ity is low to mod er ate, of ten in the range of 150-200 mD, while to tal po ros ity av er age per bore hole is com monly ex ceeds 6 %, reach ing up to 10% at max i mum, which might be con sid ered as mod er ate to good. The clay min er als con tent is mod er ate to high (30-50%), and geomechanical char ac ter is tics of the shale for ma tions are inter me di ate be tween brit tle and duc tile. No overpressure oc curs in the ba sin, ex cept for a dry gas zone in the SW Bal tic Basin. In the Biłgoraj-Narol Zone, and to a lesser de gree also in the Lublin re gion, pro nounced tec tonic de for ma tion sig nif i cantly lim its shale gas/oil po ten tial. Among 66 ex plo ra tion bore holes drilled in the ba sin so far, only 5 were lat eral bore holes with rep re sen ta tive pro duc tion test re sults. Hy dro car bon flow from the best bore holes was low to mod er ate, equal to 11.2 to 15.6 thou sand m 3 /day for gas, and 157 bbl/day (~21.4 ton/day) for oil. There is, how ever, high po ten tial to im prove pro duc tion flow rates, con nected with the frac tur ing of two net pay in ter vals at one time, as well as with sig nif i cant tech no log i cal prog ress in the ex ploi ta tion of shale bas ins dur ing the last 5 years. Com mer cially vi a ble pro duc tion might be achieved for a sin gle bore hole with es ti mated ul ti mate re cov ery ex ceed ing 30-50 thou sand tons of oil, or 60-90 mil lion m 3 of gas.

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Improved Kerogen Models for Determining Thermal Maturity and Hydrocarbon Potential of Shale

Cited by 24 publications

References 42 publications

Combined High-Resolution Solid-State ¹H/¹³C NMR Spectroscopy and ¹H NMR Relaxometry for the Characterization of Kerogen Thermal Maturation

Combined High-Resolution Solid-State ¹H/¹³C NMR Spectroscopy and ¹H NMR Relaxometry for the Characterization of Kerogen Thermal Maturation

A Chemical Framework for the Preservation of Fossil Vertebrate Cells and Soft Tissues

Lower Paleozoic oil and gas shale in the Baltic-Podlasie-Lublin Basin (central and eastern Europe) – a review

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Improved Kerogen Models for Determining Thermal Maturity and Hydrocarbon Potential of Shale

Cited by 24 publications

References 42 publications

Combined High-Resolution Solid-State 1H/13C NMR Spectroscopy and 1H NMR Relaxometry for the Characterization of Kerogen Thermal Maturation

Combined High-Resolution Solid-State 1H/13C NMR Spectroscopy and 1H NMR Relaxometry for the Characterization of Kerogen Thermal Maturation

A Chemical Framework for the Preservation of Fossil Vertebrate Cells and Soft Tissues

Lower Paleozoic oil and gas shale in the Baltic-Podlasie-Lublin Basin (central and eastern Europe) – a review

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Combined High-Resolution Solid-State ¹H/¹³C NMR Spectroscopy and ¹H NMR Relaxometry for the Characterization of Kerogen Thermal Maturation

Combined High-Resolution Solid-State ¹H/¹³C NMR Spectroscopy and ¹H NMR Relaxometry for the Characterization of Kerogen Thermal Maturation