Scholarlink

<p>The graphitization process of marine kerogen and its impact on nanopore characteristics and adsorption performance remain poorly understood, severely constraining shale gas exploration in over-mature shale reservoirs and their assessment as potential subsurface repositories for CO<sub>2</sub> and H<sub>2</sub> storage. This study systematically investigated the structural evolution, pore characteristics, and methane (CH<sub>4</sub>) adsorption capacity of the kerogen samples of Lower Cambrian shales from South China across a maturity gradient from 2.51% to 6.20% EqRo (equivalent vitrinite reflectance) using a multi-technique approach such as laser Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, low-pressure gas (N<sub>2</sub> and CO<sub>2</sub>) adsorption, and high-pressure CH<sub>4</sub> adsorption. The results revealed a well-defined three-stage evolution with covariant relationships among the three aspects. The evolution of kerogen structure, demarcated by the maturity thresholds of approximately 3.5% and 4.5% EqRo, progresses from a disordered carbon-dominated structure, through a transition of short-range ordered graphitic microcrystals, towards three-dimensionally ordered crystalline graphite, corresponding to the carbonization, pre-graphitization, and semi-graphitization, to graphitization stages, respectively. Concurrently, the evolution of kerogen micropores shows an initial increase and then a substantial decrease from the carbonization stage to the pre-graphitization stage, and up to the graphitization stage, while the homogeneity of nanopores (including both micropores and non-micropores) is markedly enhanced. Accordingly, the graphitization process drastically reduces the CH<sub>4</sub> adsorption capacity of kerogen and markedly weakens the affinity of pore surfaces to CH<sub>4</sub> molecules. Mechanistically, the structural evolution of kerogen governs the changes in pore structure (especially micropores), thereby controlling CH<sub>4</sub> adsorption performance. Based on these integrated findings, a conceptual model of the co-evolution of kerogen structure, nanopore characteristics, and adsorption capacity was established. For overmature reservoirs, the implications of graphitization to shale gas exploration were clarified, and the potential risks associated with the subsurface storage of CO<sub>2</sub> and H<sub>2</sub> were also discussed.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Graphitization of marine kerogen and its effects on nanopores and adsorption performance

  • 期刊论文

  • 发表日期：

    2026年5月20日

查看全文
  • Guangming Meng,
  • Xianming Xiao,
  • Haifeng Gai,
  • Yanming Zhao,
  • Yijie Xing,
  • Kun Zhang,
  • Yu Liu,
  • Qin Zhou,
  • Tengfei Li,
  • Wei Liu,
  • Peng Cheng,
  • Ping Gao

摘要

The graphitization process of marine kerogen and its impact on nanopore characteristics and adsorption performance remain poorly understood, severely constraining shale gas exploration in over-mature shale reservoirs and their assessment as potential subsurface repositories for CO2 and H2 storage. This study systematically investigated the structural evolution, pore characteristics, and methane (CH4) adsorption capacity of the kerogen samples of Lower Cambrian shales from South China across a maturity gradient from 2.51% to 6.20% EqRo (equivalent vitrinite reflectance) using a multi-technique approach such as laser Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, low-pressure gas (N2 and CO2) adsorption, and high-pressure CH4 adsorption. The results revealed a well-defined three-stage evolution with covariant relationships among the three aspects. The evolution of kerogen structure, demarcated by the maturity thresholds of approximately 3.5% and 4.5% EqRo, progresses from a disordered carbon-dominated structure, through a transition of short-range ordered graphitic microcrystals, towards three-dimensionally ordered crystalline graphite, corresponding to the carbonization, pre-graphitization, and semi-graphitization, to graphitization stages, respectively. Concurrently, the evolution of kerogen micropores shows an initial increase and then a substantial decrease from the carbonization stage to the pre-graphitization stage, and up to the graphitization stage, while the homogeneity of nanopores (including both micropores and non-micropores) is markedly enhanced. Accordingly, the graphitization process drastically reduces the CH4 adsorption capacity of kerogen and markedly weakens the affinity of pore surfaces to CH4 molecules. Mechanistically, the structural evolution of kerogen governs the changes in pore structure (especially micropores), thereby controlling CH4 adsorption performance. Based on these integrated findings, a conceptual model of the co-evolution of kerogen structure, nanopore characteristics, and adsorption capacity was established. For overmature reservoirs, the implications of graphitization to shale gas exploration were clarified, and the potential risks associated with the subsurface storage of CO2 and H2 were also discussed.