Research of water influence on macro and homogenized fracture toughness, brittleness and relationship between different mechanical properties of Longmaxi shale outcrop
For better understanding the water influence on shale mechanical characteristics, chip, column, powder and semi-circular bend four types of shale sample from Longmaxi outcrop processed to 5 different moisture degree, are prepared to separately conduct SEM observation for in-situ location after proce...
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| Format: | Article |
| Language: | English |
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Elsevier
2024-05-01
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| Series: | Journal of Materials Research and Technology |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785424005052 |
| _version_ | 1797249170405326848 |
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| author | Keming Gu Zhengfu Ning Ying Kang |
| author_facet | Keming Gu Zhengfu Ning Ying Kang |
| author_sort | Keming Gu |
| collection | DOAJ |
| description | For better understanding the water influence on shale mechanical characteristics, chip, column, powder and semi-circular bend four types of shale sample from Longmaxi outcrop processed to 5 different moisture degree, are prepared to separately conduct SEM observation for in-situ location after processing, AFM test and nanoindentation for data of fracture toughness calculation, uniaxial/triaxial compression test for internal friction angle, nitrogen adsorption test for pore volume, SCB test for macro fracture toughness. An improved Energy-based method is proposed to calculate micro fracture toughness based on results from AFM test, in comparison with micro fracture toughness calculated with energy method and nanoindentation curves, the results of improved energy-based method are acceptable. By analogy with elastic modulus, a new method is proposed to calculate macro fracture toughness changing ratio with rising saturation based on micro fracture toughness computed with AFM test data including maximum force, maximum depth, contact area, hardness and elastic modulus. This method can be applied to computing macro brittleness changing ratio based on micro brittleness calculated with AFM test data, its changing pattern fits the pattern of brittleness computed by internal friction angle. Unlike fracture toughness getting down consistently, shale brittleness gets down initially then climbs up with rising saturation. But average value cannot represent macro level, the linear relationship between fracture toughness and Young's modulus disappears due to moisture influence. A comparative analysis between nanoindentation and AFM is conducted from three aspects, AFM is a better method to detect micro mechanical properties influenced by some factor at different degree. |
| first_indexed | 2024-04-24T20:26:13Z |
| format | Article |
| id | doaj.art-be1a6ae720154524b08d7131ab75bcec |
| institution | Directory Open Access Journal |
| issn | 2238-7854 |
| language | English |
| last_indexed | 2024-04-24T20:26:13Z |
| publishDate | 2024-05-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Materials Research and Technology |
| spelling | doaj.art-be1a6ae720154524b08d7131ab75bcec2024-03-22T05:39:50ZengElsevierJournal of Materials Research and Technology2238-78542024-05-0130552564Research of water influence on macro and homogenized fracture toughness, brittleness and relationship between different mechanical properties of Longmaxi shale outcropKeming Gu0Zhengfu Ning1Ying Kang2State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum (Beijing), Beijing, 102249, China; College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing, ChinaState Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum (Beijing), Beijing, 102249, China; College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing, China; Corresponding author. College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing, China.State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum (Beijing), Beijing, 102249, China; College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing, ChinaFor better understanding the water influence on shale mechanical characteristics, chip, column, powder and semi-circular bend four types of shale sample from Longmaxi outcrop processed to 5 different moisture degree, are prepared to separately conduct SEM observation for in-situ location after processing, AFM test and nanoindentation for data of fracture toughness calculation, uniaxial/triaxial compression test for internal friction angle, nitrogen adsorption test for pore volume, SCB test for macro fracture toughness. An improved Energy-based method is proposed to calculate micro fracture toughness based on results from AFM test, in comparison with micro fracture toughness calculated with energy method and nanoindentation curves, the results of improved energy-based method are acceptable. By analogy with elastic modulus, a new method is proposed to calculate macro fracture toughness changing ratio with rising saturation based on micro fracture toughness computed with AFM test data including maximum force, maximum depth, contact area, hardness and elastic modulus. This method can be applied to computing macro brittleness changing ratio based on micro brittleness calculated with AFM test data, its changing pattern fits the pattern of brittleness computed by internal friction angle. Unlike fracture toughness getting down consistently, shale brittleness gets down initially then climbs up with rising saturation. But average value cannot represent macro level, the linear relationship between fracture toughness and Young's modulus disappears due to moisture influence. A comparative analysis between nanoindentation and AFM is conducted from three aspects, AFM is a better method to detect micro mechanical properties influenced by some factor at different degree.http://www.sciencedirect.com/science/article/pii/S2238785424005052WaterBrittlenessFracture toughnessYoung's modulusShaleHomogenization |
| spellingShingle | Keming Gu Zhengfu Ning Ying Kang Research of water influence on macro and homogenized fracture toughness, brittleness and relationship between different mechanical properties of Longmaxi shale outcrop Journal of Materials Research and Technology Water Brittleness Fracture toughness Young's modulus Shale Homogenization |
| title | Research of water influence on macro and homogenized fracture toughness, brittleness and relationship between different mechanical properties of Longmaxi shale outcrop |
| title_full | Research of water influence on macro and homogenized fracture toughness, brittleness and relationship between different mechanical properties of Longmaxi shale outcrop |
| title_fullStr | Research of water influence on macro and homogenized fracture toughness, brittleness and relationship between different mechanical properties of Longmaxi shale outcrop |
| title_full_unstemmed | Research of water influence on macro and homogenized fracture toughness, brittleness and relationship between different mechanical properties of Longmaxi shale outcrop |
| title_short | Research of water influence on macro and homogenized fracture toughness, brittleness and relationship between different mechanical properties of Longmaxi shale outcrop |
| title_sort | research of water influence on macro and homogenized fracture toughness brittleness and relationship between different mechanical properties of longmaxi shale outcrop |
| topic | Water Brittleness Fracture toughness Young's modulus Shale Homogenization |
| url | http://www.sciencedirect.com/science/article/pii/S2238785424005052 |
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