Heterogeneity Characterization and Main Control Factors of Nanoscale Pore Structure of the Transitional Coal Measures Shale—A Case Study of Permian in Huainan Coalfield(PDF)
《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]
- Issue:
- 2018年第04期
- Page:
- 449-461
- Research Field:
- 基础地质与矿产地质
- Publishing date:
Info
- Title:
- Heterogeneity Characterization and Main Control Factors of Nanoscale Pore Structure of the Transitional Coal Measures Shale—A Case Study of Permian in Huainan Coalfield
- Author(s):
- SHAO Chun-jing; QU Zheng-hui; YIN Hong-wei; ZUO Zhao-xi; YU Kun; YU Ke-long
- 1. School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, Jiangsu, China; 2. School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China; 3. College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Keywords:
- transitional facies; coal measures shale; pore structure; FHH fractal model; heterogeneity; main control factor; Permian; Huainan coalfield
- PACS:
- P618.13;TE122
- DOI:
- -
- Abstract:
- Nanoscale pores are important place for storage of coal measures shale gas, and have very strong heterogeneity. In order to study the heterogeneity of the pore structure of transitional coal shale, the core shale samples of Permian Shanxi Formation and Lower Shihezi Formation in Huainan coalfield were tested in total organic carbon, vitrinite reflectance, X-ray diffraction analysis of whole rock and clay, field emission scanning electron microscopy, and low-temperature liquid nitrogen adsorption experiment. The parameters of shale, such as organic geochemistry, mineral composition and content and pore structure were acquired, then selecting the relative deviation and FHH fractal model to quantitatively evaluate and analyze the heterogeneity and main controlling factors of shale reservoir pore structure. The results show that the reservoir mainly develops parallel plate-like pores and slit-like pores between lamella of clay minerals, and conical pores between particles of clay minerals; the pore size is dominated by mesopores, followed by micropores and the macropores; the pore structure has obvious fractal characteristics, which is divided into permeability pore (r＞7.5 nm) and adsorption pore (r≤7.5 nm) because of the similarity to the coal reservoir, and the permeability is more complex than that of adsorption pores; the more developed the micropores, the smaller the pore volume, the larger the surface area, the larger the fractal dimension, the more complex the pore structure, and the stronger the heterogeneity; the heterogeneity of pore structure of transitional coal shale reservoir is mainly controlled by the difference of mineral composition under different sedimentary environments and diagenetic evolution, and the heterogeneity increases with the increase of the clay minerals contents and the decrease of brittle mineral contents; compared with Lower Shihezi Formation, Shanxi Formation has lower clay minerals contents, leading to lower fractal dimension, weaker pore structure complexity, relative smaller deviation of specific surface area and average pore size, relatively uniform pore distribution, and relatively weak heterogeneity, thus, Shanxi Formation is more favorable for the storage, desorption and diffusion of shale gas, and the exploitation of shale gas may be considered to give priority.
Last Update: 2018-07-27