Kinetics of oil generation from brackish-lacustrine source rocks in the southern Bohai Sea, East China

Oil generation (C14+ hydrocarbons) of three Type II kerogen samples isolated from brackish-lacustrine mudstones from Palaeogene strata (Ed3, Es1, Es3) in the southern Bohai Sea was simulated by closed-system gold tube experiments. In addition, a series of complementary analyses (Rock-Eval pyrolysis,...

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Main Authors: Liang, Haoran, Xu, F., Grice, Kliti, Xu, G., Holman, Alex, Hopper, Peter, Fu, D., Yu, Q., Liang, J., Wang, D.
Format: Journal Article
Language:English
Published: PERGAMON-ELSEVIER SCIENCE LTD 2020
Subjects:
Online Access:http://hdl.handle.net/20.500.11937/90157
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author Liang, Haoran
Xu, F.
Grice, Kliti
Xu, G.
Holman, Alex
Hopper, Peter
Fu, D.
Yu, Q.
Liang, J.
Wang, D.
author_facet Liang, Haoran
Xu, F.
Grice, Kliti
Xu, G.
Holman, Alex
Hopper, Peter
Fu, D.
Yu, Q.
Liang, J.
Wang, D.
author_sort Liang, Haoran
building Curtin Institutional Repository
collection Online Access
description Oil generation (C14+ hydrocarbons) of three Type II kerogen samples isolated from brackish-lacustrine mudstones from Palaeogene strata (Ed3, Es1, Es3) in the southern Bohai Sea was simulated by closed-system gold tube experiments. In addition, a series of complementary analyses (Rock-Eval pyrolysis, total organic carbon, vitrinite reflectance, trace element, X-ray diffraction and flash pyrolysis-gas chromatography–mass spectrometry) were also performed to identify the bulk geochemistry, palaeo-environment and chemical composition of the kerogen. The aim of this study was to achieve a better understanding of the kinetics of oil generation from lacustrine source rocks in the southern Bohai Sea. The results show that the three samples are Type II source rocks deposited in similar palaeo-environments (hot and arid climates, anoxic conditions, and brackish water in shallow to semi-deep lakes) with consequent similarity in the chemical compositions of their kerogens. The organic matter inputs are predominantly composed of lacustrine microalgae, with a relatively small contribution from land plants. The activation energies of oil generation from these samples show a range of 44–52 kcal/mol, with a frequency factor varying from 1.116 × 1014 to 1.274 × 1014 s−1. Due to the similar palaeo-environments and chemical composition, samples in this study exhibit strong consistencies in kinetic parameters. Transformation ratio (TR) evolution curves of oil generation from the three samples, calculated under a linear heating rate (3 K/Ma), exhibit a slight difference, which varies within 4 °C at a given TR. Due to the great similarities of the three kinetic models, an average kinetic model for the Type II brackish-lacustrine source rocks in the southern Bohai Sea was established. This model integrates the characteristics of the three kinetic models and is still dominated by activation energy of 52 kcal/mol. The geological temperature of the oil generation phase for the average model in the southern Bohai Sea is from 92 to 137 °C.
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institution Curtin University Malaysia
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language English
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publishDate 2020
publisher PERGAMON-ELSEVIER SCIENCE LTD
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spelling curtin-20.500.11937-901572023-02-09T06:47:19Z Kinetics of oil generation from brackish-lacustrine source rocks in the southern Bohai Sea, East China Liang, Haoran Xu, F. Grice, Kliti Xu, G. Holman, Alex Hopper, Peter Fu, D. Yu, Q. Liang, J. Wang, D. Science & Technology Physical Sciences Geochemistry & Geophysics Activation energy activation energy Type II kerogen Palaeo-environment Kerogen composition C14+ fraction Bohai Bay Basin ARTIFICIAL MATURATION SERIES SECONDARY GAS GENERATION HYDROCARBON GENERATION PETROLEUM FORMATION BOTRYOCOCCUS-BRAUNII THERMAL-CRACKING MOLECULAR-STRUCTURE SHAHEJIE FORMATION FLASH PYROLYSIS ORGANIC-MATTER Oil generation (C14+ hydrocarbons) of three Type II kerogen samples isolated from brackish-lacustrine mudstones from Palaeogene strata (Ed3, Es1, Es3) in the southern Bohai Sea was simulated by closed-system gold tube experiments. In addition, a series of complementary analyses (Rock-Eval pyrolysis, total organic carbon, vitrinite reflectance, trace element, X-ray diffraction and flash pyrolysis-gas chromatography–mass spectrometry) were also performed to identify the bulk geochemistry, palaeo-environment and chemical composition of the kerogen. The aim of this study was to achieve a better understanding of the kinetics of oil generation from lacustrine source rocks in the southern Bohai Sea. The results show that the three samples are Type II source rocks deposited in similar palaeo-environments (hot and arid climates, anoxic conditions, and brackish water in shallow to semi-deep lakes) with consequent similarity in the chemical compositions of their kerogens. The organic matter inputs are predominantly composed of lacustrine microalgae, with a relatively small contribution from land plants. The activation energies of oil generation from these samples show a range of 44–52 kcal/mol, with a frequency factor varying from 1.116 × 1014 to 1.274 × 1014 s−1. Due to the similar palaeo-environments and chemical composition, samples in this study exhibit strong consistencies in kinetic parameters. Transformation ratio (TR) evolution curves of oil generation from the three samples, calculated under a linear heating rate (3 K/Ma), exhibit a slight difference, which varies within 4 °C at a given TR. Due to the great similarities of the three kinetic models, an average kinetic model for the Type II brackish-lacustrine source rocks in the southern Bohai Sea was established. This model integrates the characteristics of the three kinetic models and is still dominated by activation energy of 52 kcal/mol. The geological temperature of the oil generation phase for the average model in the southern Bohai Sea is from 92 to 137 °C. 2020 Journal Article http://hdl.handle.net/20.500.11937/90157 10.1016/j.orggeochem.2019.103945 English http://creativecommons.org/licenses/by-nc-nd/4.0/ PERGAMON-ELSEVIER SCIENCE LTD fulltext
spellingShingle Science & Technology
Physical Sciences
Geochemistry & Geophysics
Activation energy activation energy
Type II kerogen
Palaeo-environment
Kerogen composition
C14+ fraction
Bohai Bay Basin
ARTIFICIAL MATURATION SERIES
SECONDARY GAS GENERATION
HYDROCARBON GENERATION
PETROLEUM FORMATION
BOTRYOCOCCUS-BRAUNII
THERMAL-CRACKING
MOLECULAR-STRUCTURE
SHAHEJIE FORMATION
FLASH PYROLYSIS
ORGANIC-MATTER
Liang, Haoran
Xu, F.
Grice, Kliti
Xu, G.
Holman, Alex
Hopper, Peter
Fu, D.
Yu, Q.
Liang, J.
Wang, D.
Kinetics of oil generation from brackish-lacustrine source rocks in the southern Bohai Sea, East China
title Kinetics of oil generation from brackish-lacustrine source rocks in the southern Bohai Sea, East China
title_full Kinetics of oil generation from brackish-lacustrine source rocks in the southern Bohai Sea, East China
title_fullStr Kinetics of oil generation from brackish-lacustrine source rocks in the southern Bohai Sea, East China
title_full_unstemmed Kinetics of oil generation from brackish-lacustrine source rocks in the southern Bohai Sea, East China
title_short Kinetics of oil generation from brackish-lacustrine source rocks in the southern Bohai Sea, East China
title_sort kinetics of oil generation from brackish-lacustrine source rocks in the southern bohai sea, east china
topic Science & Technology
Physical Sciences
Geochemistry & Geophysics
Activation energy activation energy
Type II kerogen
Palaeo-environment
Kerogen composition
C14+ fraction
Bohai Bay Basin
ARTIFICIAL MATURATION SERIES
SECONDARY GAS GENERATION
HYDROCARBON GENERATION
PETROLEUM FORMATION
BOTRYOCOCCUS-BRAUNII
THERMAL-CRACKING
MOLECULAR-STRUCTURE
SHAHEJIE FORMATION
FLASH PYROLYSIS
ORGANIC-MATTER
url http://hdl.handle.net/20.500.11937/90157