Pore Structure and Migration Ability of Deep Shale Reservoirs in the Southern Sichuan Basin
Abstract
:1. Introduction
2. Geologic Background
3. Samples and Methods
3.1. Samples
3.2. Methods
3.2.1. Experimental Testing
3.2.2. Fractal Theory
3.2.3. Shale Gas Transport Capacity
4. Results
4.1. Total Organic Carbon
4.2. Mineralogy
4.3. Full Aperture Characterization
4.3.1. High-Pressure Mercury Injection
4.3.2. Low-Temperature N2 Adsorption
4.3.3. Low-Temperature CO2 Adsorption
4.3.4. Full Aperture Distribution
4.4. Fractal Characteristics
4.5. Permeability and Pores Satisfying Darcy Flow
5. Discussion
5.1. Factors Controlling Pore Complexity
5.1.1. Influence of TOC on Pore Complexity
5.1.2. The Influence of Mineral Composition on the Pore Complexity
5.1.3. The Influence of Pore Structure on the Pore Complexity
5.2. Shale Gas Migration Capacity and Its Influencing Factors
6. Conclusions
- (1)
- The principal lithogenic minerals in the Longmaxi Formation shale in the study area consist of quartz and calcite, resulting in the classification of siliceous shale, calcareous shale, and mixed shale.
- (2)
- The pore structure of the Longmaxi Formation shale in the study area is complex, with an average pore size ranging from 4.55 to 17.92 nm, pore volume ranging from 0.0131 to 0.0364 cm3/g, and specific surface area ranging from 12.01 to 21.99 m2/g. The fractal dimensions (D1) of the mesopores range from 2.452 to 2.8548, and the fractal dimensions (D2) of the macropores range from 2.9626 to 2.9786.
- (3)
- Fractal dimensions of shale are influenced by organic matter, inorganic minerals, and pore structure parameters. Both D1 and D2 exhibit positive correlations with TOC, clay mineral content, and specific surface area, while showing negative correlations with quartz. However, correlations with calcite content, pore volume, and average pore size are not statistically significant.
- (4)
- Macropores emerge as the primary contributors to the migration capability of shale reservoirs, with the permeability of shale being influenced by D2, specific surface area, and the connectivity of macropores.
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
Appendix A
Samples | Depth/m | Blocks | TOC/% | Mineral Content/% | Fractal Dimension | Lithofacies | Permeability /μD | Pore Volume /(cm3/g) | BET Surface Area/(m2/g) | Average Pore Size/nm | Proportion/% | ||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Clay | Quartz | Calcite | Plagioclase | K-Feldspar | Pyrite | D1 | D2 | ||||||||||
CN-1 | 2520.4 | Changning | 4.62 | 14.73 | 45.49 | 21.29 | 11 | 4.32 | 3.17 | 2.6064 | 2.9697 | Siliceous shale | 16.85 | 0.0241 | 15.53 | 7.35 | 9.56 |
CN-2 | 3148.4 | 4.38 | 19.91 | 48.42 | 19.4 | 5.06 | 2.68 | 4.53 | 2.6902 | 2.9636 | Siliceous shale | 25.63 | 0.0253 | 13.36 | 5.37 | 6.86 | |
CN-3 | 3166.9 | 5.2 | 13.58 | 64.9 | 19.19 | 0 | 1.27 | 1.06 | 2.66 | 2.9699 | Siliceous shale | 15.64 | 0.02321 | 16.78 | 8.17 | 6.83 | |
CN-4 | 2349.5 | 4.91 | 26.22 | 42.85 | 28.53 | 0.8 | 0.9 | 0.7 | 2.8135 | 2.9701 | Mixed shale | 16.85 | 0.02431 | 16.31 | 12.76 | 5.00 | |
WY-1 | 2569 | Weiyuan | 5.2 | 15.13 | 12.71 | 55.75 | 8.9 | 4.22 | 3.29 | 2.7152 | 2.9641 | Calcareous shale | 15.08 | 0.0336 | 16.3 | 17.92 | 4.72 |
WY-2 | 3116.74 | 4.8 | 15.25 | 10.22 | 60.39 | 8.26 | 3.86 | 2.02 | 2.7523 | 2.9678 | Calcareous shale | 25.63 | 0.0293 | 14.84 | 6.14 | 6.73 | |
WY-3 | 3784.96 | 2.9 | 9.38 | 20.04 | 49.26 | 12.36 | 2.36 | 3.7 | 2.5693 | 2.9626 | Mixed shale | 35.22 | 0.0312 | 12.01 | 6.98 | 5.84 | |
YX-1 | 4077.1 | Yuxi | 5.9 | 17.36 | 4.41 | 54.61 | 14.96 | 4.56 | 4.1 | 2.8315 | 2.9786 | Mixed shale | 4.26 | 0.0296 | 21.06 | 4.89 | 7.25 |
YX-2 | 3754 | 6 | 17.8 | 20.4 | 45.9 | 9.7 | 4 | 2.2 | 2.8548 | 2.9779 | Calcareous shale | 11.79 | 0.0364 | 21.99 | 5.16 | 5.40 | |
YX-3 | 3345 | 4.3 | 18.32 | 1.25 | 60.65 | 12.93 | 4.65 | 2.3 | 2.6316 | 2.9731 | Calcareous shale | 3.52 | 0.0298 | 18.31 | 4.89 | 6.05 | |
LZ-1 | 4039 | Luzhou | 5.6 | 18.8 | 13.8 | 52.9 | 6.7 | 2.7 | 5.1 | 2.7432 | 2.9736 | Calcareous shale | 2.13 | 0.0186 | 19.87 | 12.86 | 11.79 |
LZ-2 | 3839.7 | 5.1 | 25.5 | 16.3 | 42.3 | 7.99 | 4.31 | 3.6 | 2.5976 | 2.9718 | Mixed shale | 15.03 | 0.0216 | 18.06 | 4.55 | 4.00 | |
LZ-3 | 4926.8 | 4.4 | 21.4 | 49.2 | 18.7 | 5.5 | 1.9 | 3.3 | 2.6458 | 2.9746 | Siliceous shale | 7.05 | 0.0196 | 20.01 | 5.73 | 7.58 | |
LZ-4 | 4086.4 | 4.5 | 21.5 | 52.8 | 7.9 | 5.1 | 10.4 | 2.3 | 2.6375 | 2.9739 | Siliceous shale | 6.89 | 0.0131 | 15.84 | 4.98 | 6.76 | |
LZ-5 | 4918 | 4 | 15.4 | 63.2 | 11.9 | 3.7 | 2.6 | 3.2 | 2.7312 | 2.9638 | Siliceous shale | 22.45 | 0.0216 | 18.06 | 5.43 | 7.99 | |
LZ-6 | 4031.3 | 4.2 | 19.1 | 9.1 | 46.7 | 14.64 | 5.96 | 4.5 | 2.452 | 2.9776 | Mixed shale | 8.54 | 0.0342 | 14.53 | 9.93 | 3.73 |
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Wu, J.; Wu, Q.; Xu, L.; Yang, Y.; Liu, J.; Yin, Y.; Jiang, Z.; Tang, X.; Miao, H. Pore Structure and Migration Ability of Deep Shale Reservoirs in the Southern Sichuan Basin. Minerals 2024, 14, 100. https://doi.org/10.3390/min14010100
Wu J, Wu Q, Xu L, Yang Y, Liu J, Yin Y, Jiang Z, Tang X, Miao H. Pore Structure and Migration Ability of Deep Shale Reservoirs in the Southern Sichuan Basin. Minerals. 2024; 14(1):100. https://doi.org/10.3390/min14010100
Chicago/Turabian StyleWu, Jianfa, Qiuzi Wu, Liang Xu, Yuran Yang, Jia Liu, Yingzi Yin, Zhenxue Jiang, Xianglu Tang, and Huan Miao. 2024. "Pore Structure and Migration Ability of Deep Shale Reservoirs in the Southern Sichuan Basin" Minerals 14, no. 1: 100. https://doi.org/10.3390/min14010100