Intramolecular carbon isotope of propane from coal-derived gas reservoirs of sedimentary basins:Implications for source,generation and post-generation of hydrocarbons

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外文摘要：An intramolecular isotopic study was conducted on natural gases collected from coal-derived gas reser-voirs in sedimentary basins of China to determine their position-specific isotope distributions.The pro-pane from the Turpan-Hami Basin exhibited negative Δc-T(δ13Ccentral-δ13Cterminal)values ranging from-3.9‰ to-0.3‰,with an average of-2.1‰.Propane from the Ordos Basin,Sichuan Basin,and Tarim Basin showed positive ΔC-T values,with averages of 1.3‰,5.4‰ and 7.6‰,respectively.Position-specific carbon isotope compositions reveal the precursors and the propane generation pathways in the petroliferous basins.Propane formed from the thermal cracking of Type Ⅲ kerogen has largerδ13Ccentral and δ13Cterminal values than propane from Type Ⅰ/Ⅱ kerogen.The precursor for natural gases col-lected in this study is identified to be Type Ⅲ kerogen.Comparing our data to calculated results for ther-mal cracking of Type Ⅲ kerogen,we found that propane from the low-maturity gas reservoir in the Turpan Basin was generated via the i-propyl radical pathway,whereas propane from the Sulige tight gas reservoir in the Ordos Basin was formed via the n-propyl radical pathway.δ13Cterminal values covered a narrow range across basins,in contrast to δ13Ccentral.The terminal carbon position in propane is less impacted by microbial oxidation and more relevant to maturity levels and precursors.Thus,δ13Cterminal has a good potential to infer the origin and maturity level of natural gas.In examining post-generation processes,we proposed an improved identification strategy for microbial oxidation of natural gases,based on the position-specific carbon isotope distributions of propane.Samples from the Liaohe Depression of the Bohai Bay Basin and the Sichuan Basin were detected of post-generation microbial oxi-dation.Overall,position-specific carbon isotope composition of propane provides new insights into the generation mechanism and post-generation processes of natural gas in the geological period at the atomic level.

外文关键词：

Intramolecular isotopePosition-specific isotopeKinetic isotope effectsMicrobial anaerobic oxidation

作者：

Xiaofeng Wang、Peng Liu、Wenhui Liu、Changjie Liu、Ying Lin、Dongdong Zhang

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作者单位：

State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi'an 710069,China

College of Safety Science and Engineering,Xi'an University of Science and Technology,Xi'an 710054,China

State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 100083,China

Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China

Department of Earth and Planetary Sciences,University of California,Riverside,Riverside,CA 92521,USA

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基金：

National Natural Science Foundation of ChinaNational Natural Science Foundation of China

项目编号：

4210220241930426

出版年：

2024

DOI：

10.1016/j.gsf.2024.101806

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