Study on the rock mechanical properties of Jurassic terrestrial reservoirs: a case study of the lower sub-section of the second section in Lianggaoshan Formation of the eastern Sichuan Basin
Received date: 2024-03-01
Online published: 2025-03-13
Copyright
Triaxial compression tests of terrestrial reservoir rocks were carried out with the reservoir rocks of the Lianggaoshan Formation in the eastern Sichuan Basin as the research object. The mechanical properties, damage modes, and energy evolution laws of sandstone and shale were investigated, while the morphological characteristics of the distribution of cracks in the reservoir rocks were determined based on the fractal theory. The results show that the average values of sandstone and shale compressive strength are 293.74 MPa and 140.48 MPa respectively in the range of the studied depth. Sandstone has strong hard and brittle characteristics, showing cross-shear expansion damage mode; shale damage mode is splitting damage. The fracture distribution pattern after rock damage possesses statistical self-similarity. The shale fractal dimension is large, the complexity of the fracture network is high, and the factorability is good. In addition, the energy is mainly dissipated by energy storage and internal crack extension before the ultimate elastic energy, and the instantaneous release of stress-driven elastic energy produces macroscopic damage after the ultimate elastic energy. The results of the study can provide an understanding and theoretical reference for the development of reservoirs in terms of mechanical properties and energy evolution.
ZhuYu ZHAO , ChuanLiang YAN , YuanFang CHENG , ZhongYing HAN , JinChun XUE . Study on the rock mechanical properties of Jurassic terrestrial reservoirs: a case study of the lower sub-section of the second section in Lianggaoshan Formation of the eastern Sichuan Basin[J]. Progress in Geophysics, 2025 , 40(1) : 266 -275 . DOI: 10.6038/pg2025HH0493
表1 岩石三轴压缩试验结果Table 1 Results of triaxial compression tests on rocks |
| 层位、岩性 | 编号 | 深度/m | 高度/mm | 直径/mm | 密度/(g·mm-3) | 围压/MPa | 抗压强度/MPa | 弹性模量/GPa | 泊松比 |
|---|---|---|---|---|---|---|---|---|---|
| ⑦小层-砂岩 | 7-1 | 2582.23 | 50.17 | 25.29 | 2.658 | 30 | 204.84 | 20.15 | 0.135 |
| ⑥小层-页岩 | 6-1 | 2599.39 | 49.76 | 25.27 | 2.613 | 30 | 124.14 | 20.17 | 0.246 |
| ⑤小层-砂岩 | 5-1 | 2604.34 | 49.78 | 25.18 | 2.671 | 30 | 308.10 | 38.52 | 0.292 |
| ④小层-页岩(低GR) | 4-1 | 2620.77 | 50.10 | 25.25 | 2.667 | 30 | 145.84 | 23.04 | 0.178 |
| ③小层-砂岩 | 3-1 | 2631.31 | 49.82 | 25.21 | 2.630 | 30 | 329.08 | 35.48 | 0.209 |
| ②小层-页岩 | 2-1 | 2639.31 | 49.74 | 24.96 | 2.637 | 30 | 151.45 | 36.51 | 0.298 |
| ①小层-砂岩 | 1-1 | 2668.25 | 49.73 | 25.24 | 2.667 | 30 | 332.92 | 35.03 | 0.174 |
表2 三轴压缩条件下岩石破坏及裂缝图Table 2 Diagram of broken rocks and cracks under triaxial compression |
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