Micropore Structure of Deep Shales from the Wufeng–Longmaxi Formations, Southern Sichuan Basin, China: Insight into the Vertical Heterogeneity and Controlling Factors
Abstract
:1. Introduction
2. Regional Geological Background
3. Sampling and Methodology
3.1. Samples
3.2. Experimental Approaches
3.2.1. Organic Geochemistry and Mineral Composition
3.2.2. Field Emission-Scanning Electron Microscopy (FE-SEM)
3.2.3. Low-Pressure Gas Adsorption
3.2.4. High-Pressure Mercury Injection Porosimetry
4. Results
4.1. Mineralogical and Petrological Characteristics
4.1.1. Mineral Composition
4.1.2. Lithofacies Division
4.2. Pore Types
4.2.1. Organic Matter Pores
4.2.2. Inorganic Matter Pores
4.2.3. Microfractures
4.3. Pore Size Distribution
4.3.1. Pore Structure from LNA
4.3.2. Pore Structure from LCA
4.3.3. Pore Structure from HMI
4.3.4. Pore Connectivity
5. Discussion
5.1. Depositional Controls on the Mineral Composition
5.2. The Main Factors Controlling the Shale Pore Structure
5.2.1. Abundance of Organic Matter
5.2.2. Mineral Composition and Content
5.2.3. Evolution of Hydrocarbon Generation and Diagenesis
5.3. Effect of Critical Regional Geological Events on Shale Microstructure
5.3.1. Regional Thermal Event
5.3.2. Effect of Tectonic Event
6. Conclusions
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
- Zou, C.N.; Zhu, R.K.; Chen, Z.Q.; Ogg, J.G.; Wu, S.T.; Dong, D.Z.; Qiu, Z.; Wang, Y.M.; Wang, L.; Lin, S.H.; et al. Organic-matter-rich shales of China. Earth-Sci. Rev. 2019, 189, 51–78. [Google Scholar] [CrossRef]
- Liu, J.; Yao, Y.B.; Elsworth, D.; Liu, D.M.; Cai, Y.D.; Dong, L. Vertical Heterogeneity of the Shale Reservoir in the Lower Silurian Longmaxi Formation: Analogy between the Southeastern and Northeastern Sichuan Basin, SW China. Minerals 2017, 7, 151. [Google Scholar] [CrossRef]
- Li, H.; Tang, H.; Zheng, M. Micropore Structural Heterogeneity of Siliceous Shale Reservoir of the Longmaxi Formation in the Southern Sichuan Basin, China. Minerals 2019, 9, 548. [Google Scholar] [CrossRef]
- Curtis, J.B. Fractured shale-gas systems. AAPG Bull. 2002, 86, 1921–1938. [Google Scholar]
- Mahanta, B.; Tripathy, A.; Vishal, V.; Singh, T.; Ranjith, P. Effects of strain rate on fracture toughness and energy release rate of gas shales. Eng. Geol. 2017, 218, 39–49. [Google Scholar] [CrossRef]
- Shi, Z.; Zhao, S.; Zhou, T.; Ding, L.; Sun, S.; Cheng, F. Mineralogy and Geochemistry of the Upper Ordovician and Lower Silurian Wufeng-Longmaxi Shale on the Yangtze Platform, South China: Implications for Provenance Analysis and Shale Gas Sweet-Spot Interval. Minerals 2022, 12, 1190. [Google Scholar] [CrossRef]
- Yan, C.; Jin, Z.; Zhao, J.; Du, W.; Liu, Q. Influence of sedimentary environment on organic matter enrichment in shale: A case study of the Wufeng and Longmaxi Formations of the Sichuan Basin, China. Mar. Pet. Geol. 2018, 92, 880–894. [Google Scholar] [CrossRef]
- Chen, L.; Wang, G.; Yang, Y.; Jing, C.; Chen, M.; Tan, X. Geochemical Characteristics of Bentonite and Its Influence on Shale Reservoir Quality in Wufeng–Longmaxi Formation, South Sichuan Basin, China. Energy Fuel 2019, 33, 12366–12373. [Google Scholar] [CrossRef]
- Shu, Y.; Lu, Y.; Chen, L.; Wang, C.; Zhang, B. Factors influencing shale gas accumulation in the lower Silurian Longmaxi formation between the north and South Jiaoshiba area, Southeast Sichuan Basin, China. Mar. Pet. Geol. 2020, 111, 905–917. [Google Scholar] [CrossRef]
- Qiu, Z.; Zou, C.N. Controlling factors on the formation and distribution of “sweet-spot areas” of marine gas shales in South China and a preliminary discussion on unconventional petroleum sedimentology. J. Asian Earth Sci. 2020, 194, 103989. [Google Scholar] [CrossRef]
- Zhang, X.; Wu, C.; He, J.; Ren, Z.; Zhou, T. The Controlling Effects of Compositions on Nanopore Structure of Over-Mature Shale from the Longtan Formation in the Laochang Area, Eastern Yunnan, China. Minerals 2019, 9, 403. [Google Scholar] [CrossRef]
- Ma, K.; Zhang, B.; Wen, S.; Lin, X.; Wang, Y.; Yang, K. Quantitative Characterization and Controlling Factors of Shallow Shale Reservoir in Taiyang Anticline, Zhaotong Area, China. Minerals 2022, 12, 998. [Google Scholar] [CrossRef]
- Xu, L.; Zhang, J.; Ding, J.; Liu, T.; Shi, G.; Li, X.; Dang, W.; Cheng, Y.; Guo, R. Pore Structure and Fractal Characteristics of Different Shale Lithofacies in the Dalong Formation in the Western Area of the Lower Yangtze Platform. Minerals 2020, 10, 72. [Google Scholar] [CrossRef]
- Shangbin, C.; Yanming, Z.; Hongyan, W.; Honglin, L.; Wei, W.; Junhua, F. Structure characteristics and accumulation significance of nanopores in Longmaxi shale gas reservoir in the southern Sichuan Basin. J. China Coal Soc. 2012, 37, 438–444. [Google Scholar] [CrossRef]
- Xusheng, G.; Yuping, L.; Ruobing, L.; Wang, Q. Characteristics and controlling factors of micropore structures of the Longmaxi Shale in the Jiaoshiba area, Sichuan Basin. Nat. Gas Ind. B 2014, 1, 165–171. [Google Scholar]
- Wang, X.; Jiang, Z.; Jiang, S.; Chang, J.; Zhu, L.; Li, X.; Li, J. Full-Scale Pore Structure and Fractal Dimension of the Longmaxi Shale from the Southern Sichuan Basin: Investigations Using FE-SEM, Gas Adsorption and Mercury Intrusion Porosimetry. Minerals 2019, 9, 543. [Google Scholar] [CrossRef]
- Zhou, S.W.; Xue, H.Q.; Ning, Y.; Guo, W.; Zhang, Q. Experimental study of supercritical methane adsorption in Longmaxi shale: Insights into the density of adsorbed methane. Fuel 2018, 211, 140–148. [Google Scholar] [CrossRef]
- Yang, F.; Ning, Z.F.; Wang, Q.; Zhang, R.; Krooss, B.M. Pore structure characteristics of lower Silurian shales in the southern Sichuan Basin, China: Insights to pore development and gas storage mechanism. Int. J. Coal Geol. 2016, 156, 12–24. [Google Scholar] [CrossRef]
- Wu, J.; Yu, B.; Zhang, J.; Li, Y. Pore characteristics and controlling factors in the organic-rich shale of the Lower Silurian Longmaxi Formation revealed by samples from a well in southeastern Chongqing. Earth Sci. Front. 2013, 20, 260–269. [Google Scholar]
- Shangbin, C.; Yanming, Z.; Si, C.; Yufu, H.; Changqing, F.; Junhua, F. Hydrocarbon generation and shale gas accumulation in the Longmaxi Formation, Southern Sichuan Basin, China. Mar. Pet. Geol. 2017, 86, 248–258. [Google Scholar] [CrossRef]
- Nie, H.; Li, P.; Dang, W.; Ding, J.; Sun, C.; Liu, M.; Wang, J.; Du, W.; Zhang, P.; Li, D.; et al. Enrichment characteristics and exploration directions of deep shale gas of Ordovician–Silurian in the Sichuan Basin and its surrounding areas, China. Pet. Explor. Dev. 2022, 49, 744–757. [Google Scholar] [CrossRef]
- Wang, S.; Man, L.; Wang, S.; Wu, L.; Zhu, Y.; Li, Y.; He, Y. Lithofacies types, reservoir characteristics and silica origin of marine shales: A case study of the Wufeng formation–Longmaxi Formation in the Luzhou area, southern Sichuan Basin. Nat. Gas Ind. B 2022, 9, 394–410. [Google Scholar] [CrossRef]
- Melchin, M.J.; Mitchell, C.E.; Holmden, C.; Štorch, P. Environmental changes in the Late Ordovician-early Silurian: Review and new insights from black shales and nitrogen isotopes. Geol. Soc. Am. Bull. 2013, 125, 1635–1670. [Google Scholar] [CrossRef]
- Lazar, O.R.; Bohacs, K.M.; Macquaker, J.H.; Schieber, J.; Demko, T.M. Capturing key attributes of fine-grained sedimentary rocks in outcrops, cores, and thin sections: Nomenclature and description guidelines. J. Sediment. Res. 2015, 85, 230–246. [Google Scholar] [CrossRef]
- Loucks, R.G.; Reed, R.M.; Ruppel, S.C.; Hammes, U. Spectrum of pore types and networks in mudrocks and a descriptive classification for matrix-related mudrock pores. AAPG Bull. 2012, 96, 1071–1098. [Google Scholar] [CrossRef]
- Liu, J.; Yao, Y.; Liu, D.; Pan, Z.; Cai, Y. Comparison of Three Key Marine Shale Reservoirs in the Southeastern Margin of the Sichuan Basin, SW China. Minerals 2017, 7, 179. [Google Scholar] [CrossRef]
- Rouquerol, J.; Avnir, D.; Fairbridge, C.; Everett, D.; Haynes, J.; Pernicone, N.; Ramsay, J.; Sing, K.; Unger, K. Physical chemistry division commission on colloid and surface chemistry, subcommittee on characterization of porous solids: Recommendations for the characterization of porous solids. Pure Appl. Chem. 1994, 66, 1739–1758. [Google Scholar] [CrossRef]
- Labani, M.M.; Rezaee, R.; Saeedi, A.; Hinai, A.A. Evaluation of pore size spectrum of gas shale reservoirs using low pressure nitrogen adsorption, gas expansion and mercury porosimetry: A case study from the Perth and Canning Basins, Western Australia. J. Pet. Sci. Eng. 2013, 112, 7–16. [Google Scholar] [CrossRef]
- Han, Y.; Kwak, D.; Choi, S.Q.; Shin, C.; Lee, Y.; Kim, H. Pore Structure Characterization of Shale Using Gas Physisorption: Effect of Chemical Compositions. Minerals 2017, 7, 66. [Google Scholar] [CrossRef]
- Do, D.; Do, H. Pore characterization of carbonaceous materials by DFT and GCMC simulations: A review. Adsorpt. Sci. Technol. 2003, 21, 389–423. [Google Scholar] [CrossRef]
- Liu, J.-Y.; Qiu, Z.; Huang, W.-A.; Luo, Y.; Song, D. Nano-pore structure characterization of shales using gas adsorption and mercury intrusion techniques. J. Chem. Pharm. Res. 2014, 6, 850–857. [Google Scholar]
- Bustin, R.M.; Bustin, A.M.; Cui, X.; Ross, D.; Pathi, V.M. Impact of shale properties on pore structure and storage characteristics. In SPE Shale Gas Production Conference; SPE: Richardson, TX, USA, 2008; SPE-119892-MS. [Google Scholar]
- Brunauer, S.; Deming, L.S.; Deming, W.E.; Teller, E. On a theory of the van der Waals adsorption of gases. J. Am. Chem. Soc. 1940, 62, 1723–1732. [Google Scholar] [CrossRef]
- Kuila, U.; Prasad, M. Specific surface area and pore-size distribution in clays and shales. Geophys. Prospect. 2013, 61, 341–362. [Google Scholar] [CrossRef]
- Groen, J.C.; Peffer, L.A.; Pérez-Ramírez, J. Pore size determination in modified micro-and mesoporous materials. Pitfalls and limitations in gas adsorption data analysis. Micropor. Mesopor. Mater. 2003, 60, 1–17. [Google Scholar] [CrossRef]
- Li, T.; Tian, H.; Chen, J.; Cheng, L. Application of low pressure gas adsorption to the characterization of pore size distribution of shales: An example from Southeastern Chongqing area, China. J. Nat. Gas Geosci. 2016, 1, 221–230. [Google Scholar] [CrossRef]
- Burgess, C.G.; Everett, D.H.; Nuttall, S. Adsorption hysteresis in porous materials. Pure Appl. Chem. 1989, 61, 1845–1852. [Google Scholar] [CrossRef]
- Ding, C.; He, J.; Wu, H.; Zhang, X. Nanometer Pore Structure Characterization of Taiyuan Formation Shale in the Lin-Xing Area Based on Nitrogen Adsorption Experiments. Minerals 2021, 11, 298. [Google Scholar] [CrossRef]
- Liu, K.; Ostadhassan, M.; Sun, L.; Zou, J.; Yuan, Y.; Gentzis, T.; Zhang, Y.; Carvajal-Ortiz, H.; Rezaee, R. A comprehensive pore structure study of the Bakken Shale with SANS, N2 adsorption and mercury intrusion. Fuel 2019, 245, 274–285. [Google Scholar] [CrossRef]
- Caineng, Z.; Dazhong, D.; Yuman, W.; Xinjing, L.; Huang, J.; Shufang, W.; Quanzhong, G.; Zhang, C.; Hongyan, W.; Honglin, L. Shale gas in China: Characteristics, challenges and prospects (I). Pet. Explor. Dev. 2015, 42, 753–767. [Google Scholar]
- Wang, K. Enrichment characteristics of deep shale gas in tectonically complex regions of the southeastern sichuan basin, China. J. Nat. Gas Geosci. 2023, 8, 187–200. [Google Scholar] [CrossRef]
- Wang, Y.; Dong, D.; Li, X.; Huang, J.; Wang, S.; Wu, W. Stratigraphic sequence and sedimentary characteristics of Lower Silurian Longmaxi Formation in Sichuan Basin and its peripheral areas. Nat. Gas Ind. B 2015, 2, 222–232. [Google Scholar] [CrossRef]
- Tang, X.; Jiang, S.; Jiang, Z.; Li, Z.; He, Z.; Long, S.; Zhu, D. Heterogeneity of Paleozoic Wufeng-Longmaxi formation shale and its effects on the shale gas accumulation in the Upper Yangtze Region, China. Fuel 2019, 239, 387–402. [Google Scholar] [CrossRef]
- Liu, Z.C.; Li, H.J.; Zhang, X.X.; Fang, K.; Luo, P.; Zhu, H.H. Distribution and evolution of sedimentary facies of the Lower Silurian Longmaxi Formation in southern Sichuan and northern Guizhou area. Sediment. Geol. Tethyan Geol. 2021, 41, 436–445. [Google Scholar]
- Wang, Y.; Liu, L.; Zheng, S.; Luo, Z.; Sheng, Y.; Wang, X. Full-scale pore structure and its controlling factors of the Wufeng-Longmaxi shale, southern Sichuan Basin, China: Implications for pore evolution of highly overmature marine shale. J. Nat. Gas Sci. Eng. 2019, 67, 134–146. [Google Scholar] [CrossRef]
- Kong, L.; Wan, M.; Yan, Y.; Zou, C.; Liu, W.; Tian, C.; Yi, L.; Zhang, J. Reservoir diagenesis research of Silurian Longmaxi Formation in Sichuan Basin, China. J. Nat. Gas Geosci. 2016, 1, 203–211. [Google Scholar] [CrossRef]
- He, B.; Xu, Y.; Xiao, L.; Wang, K.; Sha, S. Generation and spatial distribution of the Emeishan large igneous province: New evidence from stratigraphic records. Acta Geol. Sin. Chin. Ed. 2003, 77, 194–202. [Google Scholar]
- Li, Y.; Li, M.; Zhang, J.; Pang, Q.; Zou, C.; Shu, H.; Wang, G. Influence of the Emeishan basalt eruption on shale gas enrichment: A case study of shale from Wufeng-Longmaxi formations in northern Yunnan and Guizhou provinces. Fuel 2020, 282, 118835. [Google Scholar] [CrossRef]
- Yang, W.; Wang, Y.; Du, W.; Song, Y.; Jiang, Z.; Wang, Q.; Xu, L.; Zhao, F.; Chen, Y.; Shi, F.; et al. Behavior of organic matter-hosted pores within shale gas reservoirs in response to differential tectonic deformation: Potential mechanisms and innovative conceptual models. J. Nat. Gas Sci. Eng. 2022, 102, 104571. [Google Scholar] [CrossRef]
- Liang, X.; Xu, J.; Wang, Y.; Fang, X.; Zhao, L.; Wu, Y.; Deng, B. The shale gas enrichment factors of Longmaxi Formation under gradient basin-mountain boundary in South Sichuan Basin: Tectono-depositional differentiation and discrepant evolution. Chin. J. Geol. 2021, 56, 60–81. [Google Scholar]
- Wu, J.F.; Zhao, S.X.; Fan, C.H.; Xia, Z.Q.; Zhang, C.L.; Cao, L.Y. Fracture characteristics of the Longmaxi Formation shale and its relationship with gas-bearing properties in Changning area, southern Sichuan. Acta Pet. Sin. 2021, 42, 428–446. [Google Scholar]
Well ID | Sample No. | Depth (m) | Formation | BET Specific Surface Area (m2/g) | Total Pore Volume (mL/g) | Average Pore Diameter (nm) |
---|---|---|---|---|---|---|
L-2 | S-1 | 3831.34 | Long-11 | 20.668 | 0.0220 | 3.408 |
L-2 | S-2 | 3836.48 | Long-11 | 29.411 | 0.0235 | 3.409 |
L-2 | S-3 | 3842.42 | Long-11 | 25.114 | 0.0275 | 3.057 |
L-2 | S-4 | 3846.78 | Long-11 | 23.001 | 0.0253 | 3.059 |
L-2 | S-5 | 3847.58 | WuFeng | 17.351 | 0.0177 | 3.412 |
Well ID | Sample No. | Depth (m) | Formation | DFT Specific Surface Area (m2/g) | DFT Total Pore Volume (mL/g) |
---|---|---|---|---|---|
L-2 | S-1 | 3831.34 | Long-11 | 6.960 | 0.004 |
L-2 | S-2 | 3836.48 | Long-11 | 9.787 | 0.006 |
L-2 | S-3 | 3842.42 | Long-11 | 9.203 | 0.010 |
L-2 | S-4 | 3846.78 | Long-11 | 7.490 | 0.006 |
L-2 | S-5 | 3847.58 | WuFeng | 5.192 | 0.005 |
Well ID | Sample No. | Depth (m) | Pore Volume (mL/g) | Specific Surface Area (m2/g) | Average Pore Diameter (nm) | Porosity (%) |
---|---|---|---|---|---|---|
L-2 | S-1 | 3831.34 | 0.0054 | 1.446 | 14.89 | 1.441 |
L-2 | S-2 | 3836.48 | 0.0066 | 2.460 | 10.78 | 1.733 |
L-2 | S-3 | 3842.42 | 0.0056 | 1.592 | 14.10 | 1.459 |
L-2 | S-4 | 3846.78 | 0.0064 | 2.487 | 10.30 | 1.641 |
L-2 | S-5 | 3847.58 | 0.0059 | 1.524 | 15.46 | 1.472 |
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Yang, H.; Zhao, S.; Li, B.; Liu, Y.; Zheng, M.; Zhang, J.; Liu, Y.; Wang, G.; Yin, M.; Cao, L. Micropore Structure of Deep Shales from the Wufeng–Longmaxi Formations, Southern Sichuan Basin, China: Insight into the Vertical Heterogeneity and Controlling Factors. Minerals 2023, 13, 1347. https://doi.org/10.3390/min13101347
Yang H, Zhao S, Li B, Liu Y, Zheng M, Zhang J, Liu Y, Wang G, Yin M, Cao L. Micropore Structure of Deep Shales from the Wufeng–Longmaxi Formations, Southern Sichuan Basin, China: Insight into the Vertical Heterogeneity and Controlling Factors. Minerals. 2023; 13(10):1347. https://doi.org/10.3390/min13101347
Chicago/Turabian StyleYang, Hongzhi, Shengxian Zhao, Bo Li, Yong Liu, Majia Zheng, Jian Zhang, Yongyang Liu, Gaoxiang Wang, Meixuan Yin, and Lieyan Cao. 2023. "Micropore Structure of Deep Shales from the Wufeng–Longmaxi Formations, Southern Sichuan Basin, China: Insight into the Vertical Heterogeneity and Controlling Factors" Minerals 13, no. 10: 1347. https://doi.org/10.3390/min13101347
APA StyleYang, H., Zhao, S., Li, B., Liu, Y., Zheng, M., Zhang, J., Liu, Y., Wang, G., Yin, M., & Cao, L. (2023). Micropore Structure of Deep Shales from the Wufeng–Longmaxi Formations, Southern Sichuan Basin, China: Insight into the Vertical Heterogeneity and Controlling Factors. Minerals, 13(10), 1347. https://doi.org/10.3390/min13101347