首页|Thermal Evolution of Organic Matter in Low-Maturity Shale: A Multimodal Nanoscale Investigation

Thermal Evolution of Organic Matter in Low-Maturity Shale: A Multimodal Nanoscale Investigation

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  • NETL
  • NSTL
  • Amer Chemical Soc
Systematic characterization of the nanoscale geomechanical and geochemical evolution of organic matter at elevated temperatures is critical for assessing the technical feasibility of in situ thermal methods in the development of low-maturity shale oil and gas. This study investigates the pyrolysis process of low-maturity, organic-rich shale from Yanchang Formation, focusing on thermal evolution in morphology, geochemistry, and geomechanical properties. The comprehensive analysis is performed through a series of sophisticated techniques, including thermogravimetric analysis coupled with thermogravimetric-Fourier transform infrared-gas chromatography/mass spectrometry (TG-FTIR-GC/MS), backscattered electron of the scanning electron microscopy (BSE-SEM), micro-Raman spectroscopy, atomic force microscopy-infrared spectroscopy (AFM-IR), and AFM PeakForce quantitative nanomechanics (PFQNM). Pyrolysis products evolve across three stages: water vapor dominates below 200 ℃; hydrocarbons, CO_2, and sulfur compounds release in the range of 200-650 ℃; and carbonate decomposition drives CO_2 emissions above 650 ℃. Heating induces significant morphological alterations, including surface shrinkage, pore collapse, and thermal cracks (notably above 400 ℃). Geochemical analyses show that the differences in structure among solid bitumen, vitrinite, and inertinite decrease as the temperature increases, alongside detaching aliphatic side chains and oxygenated functional groups and increasing the degree of aromatization. Geomechanical properties, measured via AFM-PFQNM, demonstrate an initial decrease in Young's modulus (25-250 ℃) due to pore water loss, followed by modulus increase (250-600 ℃) attributed to the aromaticity enhancement and matrix shrinkage. These insights advance the understanding of in situ thermal conversion processes, offering practical guidelines for enhancing hydrocarbon recovery from low-maturity shale reservoirs. The multidisciplinary approaches resolve the interplay among thermal, chemical, and mechanical dynamics in shale pyrolysis.

Yingjie Li、Tianhao Wu、Junliang Zhao、Guorui Wang、Dongxiao Zhang

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Eastern Institute for Advanced Study, Eastern Institute of Technology, Ningbo, Zhejiang 315200, P. R. China||CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei 230026 Anhui, P. R. China

Eastern Institute for Advanced Study, Eastern Institute of Technology, Ningbo, Zhejiang 315200, P. R. China||Ningbo Institute of Digital Twin, Eastern Institute of Technology, Ningbo, Zhejiang 315200, P. R. China||Zhejiang Key Laboratory of Industrial Intelligence and Digital Twin, Eastern Institute of Technology, Ningbo 315200 Zhejiang, P. R. China

China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500 Sichuan, P. R. China

CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei 230026 Anhui, P. R. China

Eastern Institute for Advanced Study, Eastern Institute of Technology, Ningbo, Zhejiang 315200, P. R. China||Zhejiang Key Laboratory of Industrial Intelligence and Digital Twin, Eastern Institute of Technology, Ningbo 315200 Zhejiang, P. R. China

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2025

10.1021/acs.energyfuels.5c00360

Energy & fuels

Energy & fuels

ISSN：0887-0624
年,卷(期)：2025.39(16)
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