Research on the micro-pore structure and multiscale fractal characteristics of shale under supercritical CO2 action: A case study of the Chang 73 submember in the Ordos Basin, China
To elucidate the mechanism of supercritical CO2 (ScCO2) on the microporous structure of shale, this study focuses on the Chang 73 submember of the Yanchang Formation in the Ordos Basin. Utilizing a combination of organic geochemical and mineral composition analyses, low-temperature gas (CO2 and N2)...
Saved in:
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
KeAi Communications Co., Ltd.
2025-06-01
|
| Series: | Journal of Natural Gas Geoscience |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2468256X25000288 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1849421491897106432 |
|---|---|
| author | Lili Jiang Leng Tian Zhangxing Chen Zechuan Wang Wenkui Huang Xiaolong Chai |
| author_facet | Lili Jiang Leng Tian Zhangxing Chen Zechuan Wang Wenkui Huang Xiaolong Chai |
| author_sort | Lili Jiang |
| collection | DOAJ |
| description | To elucidate the mechanism of supercritical CO2 (ScCO2) on the microporous structure of shale, this study focuses on the Chang 73 submember of the Yanchang Formation in the Ordos Basin. Utilizing a combination of organic geochemical and mineral composition analyses, low-temperature gas (CO2 and N2) adsorption experiments and nuclear magnetic resonance (NMR) scanning methods are employed—combined with multiscale fractal theory—the research comprehensively analyze the changes in shale microporous structure and its fractal characteristics under ScCO2 treatment. The results show that after ScCO2 treatment, the total organic carbon (TOC) content of the shale samples decreases, the quartz content increases, while the contents of clay minerals and feldspar decrease. Notably, TOC and mineral components are more sensitive to pressure changes compared to temperature variations. Additionally, shale pores are mainly distributed in the micropore (0–2 nm) and mesopore (2–50 nm) ranges, contributing significantly to the specific surface area, while macropores (>50 nm), though fewer, considerably contribute to the total pore volume. Following ScCO2 treatment, the total specific surface area of shale samples decreases, whereas total pore volume, average pore diameter, and effective porosity increase. Specifically, total specific surface area and average pore diameter are more sensitive to temperature, while total pore volume and effective porosity are more influenced by pressure. The shale pores exhibit multi-scale fractal characteristics, with micropores displaying higher fractal dimensions than meso- and macropores. After ScCO2 treatment, fractal dimensions at all scales decline, indicating an improvement in the complexity of the shale pore structure. A significant positive correlation exists between the fractal dimension of micropores and TOC content, whereas meso- and macropore fractal dimensions have a stronger correlation with quartz and clay mineral content. These findings indicate that changes in shale mineral characteristics are intrinsic factors affecting microporous structure, while ScCO2 treatment conditions are important external factors. The interaction of both determines the evolution of shale pore structures, providing a valuable scientific basis and practical guidance for the optimal selection of carbon capture, utilization, and storage (CCUS) target layers. |
| format | Article |
| id | doaj-art-6d5cf3d1f6b243749b0bd9b558e437d2 |
| institution | Kabale University |
| issn | 2468-256X |
| language | English |
| publishDate | 2025-06-01 |
| publisher | KeAi Communications Co., Ltd. |
| record_format | Article |
| series | Journal of Natural Gas Geoscience |
| spelling | doaj-art-6d5cf3d1f6b243749b0bd9b558e437d22025-08-20T03:31:27ZengKeAi Communications Co., Ltd.Journal of Natural Gas Geoscience2468-256X2025-06-0110315917810.1016/j.jnggs.2025.05.003Research on the micro-pore structure and multiscale fractal characteristics of shale under supercritical CO2 action: A case study of the Chang 73 submember in the Ordos Basin, ChinaLili Jiang0Leng Tian1Zhangxing Chen2Zechuan Wang3Wenkui Huang4Xiaolong Chai5College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing, 102249, China; Engineering Research Center of Gas Energy Development and Utilization, Ministry of Education, China University of Petroleum (Beijing), Beijing, 102249, China; University of Calgary, Calgary, T2N 1N4, CanadaCollege of Petroleum Engineering, China University of Petroleum (Beijing), Beijing, 102249, China; Engineering Research Center of Gas Energy Development and Utilization, Ministry of Education, China University of Petroleum (Beijing), Beijing, 102249, China; Corresponding author. College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing, 102249, China.University of Calgary, Calgary, T2N 1N4, Canada; Ningbo Eastern University of Technology, Ningbo, 315200, ChinaCollege of Petroleum Engineering, China University of Petroleum (Beijing), Beijing, 102249, China; Engineering Research Center of Gas Energy Development and Utilization, Ministry of Education, China University of Petroleum (Beijing), Beijing, 102249, ChinaCollege of Petroleum Engineering, China University of Petroleum (Beijing), Beijing, 102249, China; Engineering Research Center of Gas Energy Development and Utilization, Ministry of Education, China University of Petroleum (Beijing), Beijing, 102249, ChinaCollege of Petroleum Engineering, China University of Petroleum (Beijing), Beijing, 102249, China; Engineering Research Center of Gas Energy Development and Utilization, Ministry of Education, China University of Petroleum (Beijing), Beijing, 102249, ChinaTo elucidate the mechanism of supercritical CO2 (ScCO2) on the microporous structure of shale, this study focuses on the Chang 73 submember of the Yanchang Formation in the Ordos Basin. Utilizing a combination of organic geochemical and mineral composition analyses, low-temperature gas (CO2 and N2) adsorption experiments and nuclear magnetic resonance (NMR) scanning methods are employed—combined with multiscale fractal theory—the research comprehensively analyze the changes in shale microporous structure and its fractal characteristics under ScCO2 treatment. The results show that after ScCO2 treatment, the total organic carbon (TOC) content of the shale samples decreases, the quartz content increases, while the contents of clay minerals and feldspar decrease. Notably, TOC and mineral components are more sensitive to pressure changes compared to temperature variations. Additionally, shale pores are mainly distributed in the micropore (0–2 nm) and mesopore (2–50 nm) ranges, contributing significantly to the specific surface area, while macropores (>50 nm), though fewer, considerably contribute to the total pore volume. Following ScCO2 treatment, the total specific surface area of shale samples decreases, whereas total pore volume, average pore diameter, and effective porosity increase. Specifically, total specific surface area and average pore diameter are more sensitive to temperature, while total pore volume and effective porosity are more influenced by pressure. The shale pores exhibit multi-scale fractal characteristics, with micropores displaying higher fractal dimensions than meso- and macropores. After ScCO2 treatment, fractal dimensions at all scales decline, indicating an improvement in the complexity of the shale pore structure. A significant positive correlation exists between the fractal dimension of micropores and TOC content, whereas meso- and macropore fractal dimensions have a stronger correlation with quartz and clay mineral content. These findings indicate that changes in shale mineral characteristics are intrinsic factors affecting microporous structure, while ScCO2 treatment conditions are important external factors. The interaction of both determines the evolution of shale pore structures, providing a valuable scientific basis and practical guidance for the optimal selection of carbon capture, utilization, and storage (CCUS) target layers.http://www.sciencedirect.com/science/article/pii/S2468256X25000288Supercritical CO2ShaleMicro-pore structureMultiscale fractalLow-temperature gas adsorptionNuclear magnetic resonance |
| spellingShingle | Lili Jiang Leng Tian Zhangxing Chen Zechuan Wang Wenkui Huang Xiaolong Chai Research on the micro-pore structure and multiscale fractal characteristics of shale under supercritical CO2 action: A case study of the Chang 73 submember in the Ordos Basin, China Journal of Natural Gas Geoscience Supercritical CO2 Shale Micro-pore structure Multiscale fractal Low-temperature gas adsorption Nuclear magnetic resonance |
| title | Research on the micro-pore structure and multiscale fractal characteristics of shale under supercritical CO2 action: A case study of the Chang 73 submember in the Ordos Basin, China |
| title_full | Research on the micro-pore structure and multiscale fractal characteristics of shale under supercritical CO2 action: A case study of the Chang 73 submember in the Ordos Basin, China |
| title_fullStr | Research on the micro-pore structure and multiscale fractal characteristics of shale under supercritical CO2 action: A case study of the Chang 73 submember in the Ordos Basin, China |
| title_full_unstemmed | Research on the micro-pore structure and multiscale fractal characteristics of shale under supercritical CO2 action: A case study of the Chang 73 submember in the Ordos Basin, China |
| title_short | Research on the micro-pore structure and multiscale fractal characteristics of shale under supercritical CO2 action: A case study of the Chang 73 submember in the Ordos Basin, China |
| title_sort | research on the micro pore structure and multiscale fractal characteristics of shale under supercritical co2 action a case study of the chang 73 submember in the ordos basin china |
| topic | Supercritical CO2 Shale Micro-pore structure Multiscale fractal Low-temperature gas adsorption Nuclear magnetic resonance |
| url | http://www.sciencedirect.com/science/article/pii/S2468256X25000288 |
| work_keys_str_mv | AT lilijiang researchonthemicroporestructureandmultiscalefractalcharacteristicsofshaleundersupercriticalco2actionacasestudyofthechang73submemberintheordosbasinchina AT lengtian researchonthemicroporestructureandmultiscalefractalcharacteristicsofshaleundersupercriticalco2actionacasestudyofthechang73submemberintheordosbasinchina AT zhangxingchen researchonthemicroporestructureandmultiscalefractalcharacteristicsofshaleundersupercriticalco2actionacasestudyofthechang73submemberintheordosbasinchina AT zechuanwang researchonthemicroporestructureandmultiscalefractalcharacteristicsofshaleundersupercriticalco2actionacasestudyofthechang73submemberintheordosbasinchina AT wenkuihuang researchonthemicroporestructureandmultiscalefractalcharacteristicsofshaleundersupercriticalco2actionacasestudyofthechang73submemberintheordosbasinchina AT xiaolongchai researchonthemicroporestructureandmultiscalefractalcharacteristicsofshaleundersupercriticalco2actionacasestudyofthechang73submemberintheordosbasinchina |