Causes and geochemical significance of total organic carbon anomaly in solid residue samples from source rock pyrolysis simulation experiments in a closed system
Under natural evolution, the total organic carbon (TOC) content of source rocks typically decreases as maturity increases. However, in later stages of pyrolysis simulation experiments conducted in a closed system, the TOC content of solid residue samples would anomalously increase instead of decreas...
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Editorial Office of Petroleum Geology and Experiment
2024-11-01
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| Series: | Shiyou shiyan dizhi |
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| Online Access: | https://www.sysydz.net/cn/article/doi/10.11781/sysydz2024061275 |
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| author | Hui CANG Zhijun CHEN Dong YANG Yiguo CHEN Changchun HAN Ziliang LI Lingling CHEN |
| author_facet | Hui CANG Zhijun CHEN Dong YANG Yiguo CHEN Changchun HAN Ziliang LI Lingling CHEN |
| author_sort | Hui CANG |
| collection | DOAJ |
| description | Under natural evolution, the total organic carbon (TOC) content of source rocks typically decreases as maturity increases. However, in later stages of pyrolysis simulation experiments conducted in a closed system, the TOC content of solid residue samples would anomalously increase instead of decreasing. By analyzing data from pyrolysis simulation experiments on lacustrine source rock samples from the Mesozoic Yingen-Ejinaqi Basin, the causes of this TOC content anomaly were investigated, and its geochemical significance was explored. The results suggested that this anomaly was related to secondary cracking of crude oil. In the closed system of the experiments, early-formed crude oil was trapped in the reactor, unable to be discharged. As the temperature increased, large-scale oil cracking occurred, converting it into gaseous hydrocarbons and generating pyrobitumen. The insoluble pyrobitumen adhered to the solid residue samples, resulting in an increase of TOC content. Based on TOC variation curve of solid residue samples from the pyrolysis simulation experiments, a new method was established to determine the main gas generation threshold for oil cracking in different types of source rocks. The significant amount of pyrobitumen generated, accompanied by an increase in TOC content, indicated the onset of large-scale oil cracking and gas generation. This method overcomes the shortcomings of existing methods, such as inevitable human errors in determining the main gas generation threshold and the inability to conduct more in-depth study on mixed-source oils. |
| format | Article |
| id | doaj-art-b5cb36b97c3547f8bdc3a23380869f81 |
| institution | Kabale University |
| issn | 1001-6112 |
| language | zho |
| publishDate | 2024-11-01 |
| publisher | Editorial Office of Petroleum Geology and Experiment |
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| series | Shiyou shiyan dizhi |
| spelling | doaj-art-b5cb36b97c3547f8bdc3a23380869f812024-12-17T04:28:51ZzhoEditorial Office of Petroleum Geology and ExperimentShiyou shiyan dizhi1001-61122024-11-014661275128510.11781/sysydz2024061275sysydz-46-6-1275Causes and geochemical significance of total organic carbon anomaly in solid residue samples from source rock pyrolysis simulation experiments in a closed systemHui CANG0Zhijun CHEN1Dong YANG2Yiguo CHEN3Changchun HAN4Ziliang LI5Lingling CHEN6Research Institute of Yanchang Petroleum (Group) Co., Ltd., Xi'an, Shaanxi 710075, ChinaResearch Institute of Yanchang Petroleum (Group) Co., Ltd., Xi'an, Shaanxi 710075, ChinaDownhole Services Company of CNPC Bohai Drilling Engineering Company Limited, Renqiu, Hebei 062552, ChinaResearch Institute of Yanchang Petroleum (Group) Co., Ltd., Xi'an, Shaanxi 710075, ChinaResearch Institute of Yanchang Petroleum (Group) Co., Ltd., Xi'an, Shaanxi 710075, ChinaResearch Institute of Yanchang Petroleum (Group) Co., Ltd., Xi'an, Shaanxi 710075, ChinaResearch Institute of Yanchang Petroleum (Group) Co., Ltd., Xi'an, Shaanxi 710075, ChinaUnder natural evolution, the total organic carbon (TOC) content of source rocks typically decreases as maturity increases. However, in later stages of pyrolysis simulation experiments conducted in a closed system, the TOC content of solid residue samples would anomalously increase instead of decreasing. By analyzing data from pyrolysis simulation experiments on lacustrine source rock samples from the Mesozoic Yingen-Ejinaqi Basin, the causes of this TOC content anomaly were investigated, and its geochemical significance was explored. The results suggested that this anomaly was related to secondary cracking of crude oil. In the closed system of the experiments, early-formed crude oil was trapped in the reactor, unable to be discharged. As the temperature increased, large-scale oil cracking occurred, converting it into gaseous hydrocarbons and generating pyrobitumen. The insoluble pyrobitumen adhered to the solid residue samples, resulting in an increase of TOC content. Based on TOC variation curve of solid residue samples from the pyrolysis simulation experiments, a new method was established to determine the main gas generation threshold for oil cracking in different types of source rocks. The significant amount of pyrobitumen generated, accompanied by an increase in TOC content, indicated the onset of large-scale oil cracking and gas generation. This method overcomes the shortcomings of existing methods, such as inevitable human errors in determining the main gas generation threshold and the inability to conduct more in-depth study on mixed-source oils.https://www.sysydz.net/cn/article/doi/10.11781/sysydz2024061275pyrolysis simulation experimentpyrobitumenmain oil cracking gas generation thresholdtotal organic carbon contentpyrolysis simulation solid residue samplessource rock |
| spellingShingle | Hui CANG Zhijun CHEN Dong YANG Yiguo CHEN Changchun HAN Ziliang LI Lingling CHEN Causes and geochemical significance of total organic carbon anomaly in solid residue samples from source rock pyrolysis simulation experiments in a closed system Shiyou shiyan dizhi pyrolysis simulation experiment pyrobitumen main oil cracking gas generation threshold total organic carbon content pyrolysis simulation solid residue samples source rock |
| title | Causes and geochemical significance of total organic carbon anomaly in solid residue samples from source rock pyrolysis simulation experiments in a closed system |
| title_full | Causes and geochemical significance of total organic carbon anomaly in solid residue samples from source rock pyrolysis simulation experiments in a closed system |
| title_fullStr | Causes and geochemical significance of total organic carbon anomaly in solid residue samples from source rock pyrolysis simulation experiments in a closed system |
| title_full_unstemmed | Causes and geochemical significance of total organic carbon anomaly in solid residue samples from source rock pyrolysis simulation experiments in a closed system |
| title_short | Causes and geochemical significance of total organic carbon anomaly in solid residue samples from source rock pyrolysis simulation experiments in a closed system |
| title_sort | causes and geochemical significance of total organic carbon anomaly in solid residue samples from source rock pyrolysis simulation experiments in a closed system |
| topic | pyrolysis simulation experiment pyrobitumen main oil cracking gas generation threshold total organic carbon content pyrolysis simulation solid residue samples source rock |
| url | https://www.sysydz.net/cn/article/doi/10.11781/sysydz2024061275 |
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