Geochemical characteristic of different-lithofacies source rocks and its implications for ultradeep hydrocarbon exploration in the lower cambrian Yuertus formation, Tarim basin

Abstract The Tarim Basin harbors abundant deep to ultra-deep hydrocarbon resources, yet detailed oil-source correlation remains to be further investigated. As a potential key source rock, the organic geochemical characteristics of the Yuertus Formation (Є1y) warrant additional research. This study i...

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Main Authors: Qianghao Zeng, Taohua He, Ya Zhao, Ke Zhang, Zhigang Wen, Yaohui Xu, Jiayi He, Weichao Tian, Shuangfang Lu, Wangming Cheng, Zhou Xie, Kaiwen Xue, Changjun Ji
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-09636-1
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author Qianghao Zeng
Taohua He
Ya Zhao
Ke Zhang
Zhigang Wen
Yaohui Xu
Jiayi He
Weichao Tian
Shuangfang Lu
Wangming Cheng
Zhou Xie
Kaiwen Xue
Changjun Ji
author_facet Qianghao Zeng
Taohua He
Ya Zhao
Ke Zhang
Zhigang Wen
Yaohui Xu
Jiayi He
Weichao Tian
Shuangfang Lu
Wangming Cheng
Zhou Xie
Kaiwen Xue
Changjun Ji
author_sort Qianghao Zeng
collection DOAJ
description Abstract The Tarim Basin harbors abundant deep to ultra-deep hydrocarbon resources, yet detailed oil-source correlation remains to be further investigated. As a potential key source rock, the organic geochemical characteristics of the Yuertus Formation (Є1y) warrant additional research. This study integrates biomarker, carbon, and sulfur isotope data from Є1y source rocks in existing wells and outcrops across the eastern, northern, and northwestern Tarim Basin to better constrain the distribution, hydrocarbon generation potential, biomarker features, and oil-source relations of Є1y. Results reveal that Є1y exhibits diverse lithofacies, including calcareous mudstones, siliceous shales, and shales as potential source rocks. The calcareous mudstone shows the highest total organic carbon (TOC) content (up to 29.8%), characterized by Type II kerogens and mature to over-mature thermal maturity. Stable biomarkers including triaromatic steroids (TAS), triaromatic dinoflagellate steroids (TDSI), and aryl isoprenoids (1-alkyl-2,3,6-trimethylbenzenes, ATMBs) reveal significant differences among the three lithological types of source rocks: Calcareous mudstones exhibit biomarker distribution patterns similar to those of classical Ordovician source rocks (C26R + C27S TAS < C28S TAS, TDSI < 0.6), while simultaneously containing high abundances of ATMBs characteristic of the Є1y. Siliceous rocks display typical Cambrian characteristics with low C28 TAS, high TDSI, but absence of ATMBs. Shales present typical Cambrian features with low C28 TAS, high TDSI, and low ATMBs. Oil-source correlation based on n-alkane’ carbon and sulfur isotopes suggests that calcareous shales are likely one of the primary sources for currently explored oils. These findings enrich the fundamental understanding of deep and ultra-deep hydrocarbon exploration in the Tarim Basin and provide new insights into the reassessment of oil-source relations.
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spelling doaj-art-baa80a16d3f8484da58964d8603ae5cc2025-08-20T04:01:36ZengNature PortfolioScientific Reports2045-23222025-07-0115111310.1038/s41598-025-09636-1Geochemical characteristic of different-lithofacies source rocks and its implications for ultradeep hydrocarbon exploration in the lower cambrian Yuertus formation, Tarim basinQianghao Zeng0Taohua He1Ya Zhao2Ke Zhang3Zhigang Wen4Yaohui Xu5Jiayi He6Weichao Tian7Shuangfang Lu8Wangming Cheng9Zhou Xie10Kaiwen Xue11Changjun Ji12Key Laboratory of Oil and Gas Resources and Exploration Technology, Ministry of Education, Yangtze UniversityKey Laboratory of Oil and Gas Resources and Exploration Technology, Ministry of Education, Yangtze UniversityKey Laboratory of Oil and Gas Resources and Exploration Technology, Ministry of Education, Yangtze UniversityPetroleum Exploration & Production Research Institute, Tarim Oilfield Company, PetroChinaKey Laboratory of Oil and Gas Resources and Exploration Technology, Ministry of Education, Yangtze UniversityKey Laboratory of Oil and Gas Resources and Exploration Technology, Ministry of Education, Yangtze UniversityKey Laboratory of Oil and Gas Resources and Exploration Technology, Ministry of Education, Yangtze UniversityKey Laboratory of Oil and Gas Resources and Exploration Technology, Ministry of Education, Yangtze UniversitySanya Offshore Oil & Gas Research Institute, Northeast Petroleum UniversityPetroleum Exploration & Production Research Institute, Tarim Oilfield Company, PetroChinaPetroleum Exploration & Production Research Institute, Tarim Oilfield Company, PetroChinaKey Laboratory of Oil and Gas Resources and Exploration Technology, Ministry of Education, Yangtze UniversityChinese Academy of Geological SciencesAbstract The Tarim Basin harbors abundant deep to ultra-deep hydrocarbon resources, yet detailed oil-source correlation remains to be further investigated. As a potential key source rock, the organic geochemical characteristics of the Yuertus Formation (Є1y) warrant additional research. This study integrates biomarker, carbon, and sulfur isotope data from Є1y source rocks in existing wells and outcrops across the eastern, northern, and northwestern Tarim Basin to better constrain the distribution, hydrocarbon generation potential, biomarker features, and oil-source relations of Є1y. Results reveal that Є1y exhibits diverse lithofacies, including calcareous mudstones, siliceous shales, and shales as potential source rocks. The calcareous mudstone shows the highest total organic carbon (TOC) content (up to 29.8%), characterized by Type II kerogens and mature to over-mature thermal maturity. Stable biomarkers including triaromatic steroids (TAS), triaromatic dinoflagellate steroids (TDSI), and aryl isoprenoids (1-alkyl-2,3,6-trimethylbenzenes, ATMBs) reveal significant differences among the three lithological types of source rocks: Calcareous mudstones exhibit biomarker distribution patterns similar to those of classical Ordovician source rocks (C26R + C27S TAS < C28S TAS, TDSI < 0.6), while simultaneously containing high abundances of ATMBs characteristic of the Є1y. Siliceous rocks display typical Cambrian characteristics with low C28 TAS, high TDSI, but absence of ATMBs. Shales present typical Cambrian features with low C28 TAS, high TDSI, and low ATMBs. Oil-source correlation based on n-alkane’ carbon and sulfur isotopes suggests that calcareous shales are likely one of the primary sources for currently explored oils. These findings enrich the fundamental understanding of deep and ultra-deep hydrocarbon exploration in the Tarim Basin and provide new insights into the reassessment of oil-source relations.https://doi.org/10.1038/s41598-025-09636-1Tarim basinYuertus formationBiomarkersStable isotopesOil-source correlation
spellingShingle Qianghao Zeng
Taohua He
Ya Zhao
Ke Zhang
Zhigang Wen
Yaohui Xu
Jiayi He
Weichao Tian
Shuangfang Lu
Wangming Cheng
Zhou Xie
Kaiwen Xue
Changjun Ji
Geochemical characteristic of different-lithofacies source rocks and its implications for ultradeep hydrocarbon exploration in the lower cambrian Yuertus formation, Tarim basin
Scientific Reports
Tarim basin
Yuertus formation
Biomarkers
Stable isotopes
Oil-source correlation
title Geochemical characteristic of different-lithofacies source rocks and its implications for ultradeep hydrocarbon exploration in the lower cambrian Yuertus formation, Tarim basin
title_full Geochemical characteristic of different-lithofacies source rocks and its implications for ultradeep hydrocarbon exploration in the lower cambrian Yuertus formation, Tarim basin
title_fullStr Geochemical characteristic of different-lithofacies source rocks and its implications for ultradeep hydrocarbon exploration in the lower cambrian Yuertus formation, Tarim basin
title_full_unstemmed Geochemical characteristic of different-lithofacies source rocks and its implications for ultradeep hydrocarbon exploration in the lower cambrian Yuertus formation, Tarim basin
title_short Geochemical characteristic of different-lithofacies source rocks and its implications for ultradeep hydrocarbon exploration in the lower cambrian Yuertus formation, Tarim basin
title_sort geochemical characteristic of different lithofacies source rocks and its implications for ultradeep hydrocarbon exploration in the lower cambrian yuertus formation tarim basin
topic Tarim basin
Yuertus formation
Biomarkers
Stable isotopes
Oil-source correlation
url https://doi.org/10.1038/s41598-025-09636-1
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