Pore structure characterization for the Longmaxi and Niutitang shales in the Upper Yangtze Platform, South China: Evidence from focused ion beam–He ion microscopy, nano-computerized tomography and gas adsorption analysis

Wang, Pengfei; Jiang, Zhenxue; Chen, Lei; Yin, Li; Li, Zhuo; Zhang, Chen; Tang, Xianglu; Wang, Guozhen

doi:10.1016/j.marpetgeo.2016.09.001

Cited by 128 publications

(77 citation statements)

References 52 publications

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“…Fractures in Barnett and Woodford shales occur at a variety of scales (Gale & Holder, ; Gale, Reed, & Holder, ; Portas, ; Slatt, ) and are significant in any general investigation of shale properties, particularly those related to well‐drilling and artificial fracture treatment. The microfractures are also well developed in continental shales (J. J. Li, Wang, et al, ; J. J. Li, Yin, et al, ; P. F. Wang et al, ; M. Wang, Sherwood, et al, ; M. Wang, Wilkins, et al, ; M. Wang, Xue, et al, ; P. F. Zhang et al, ). In the SDT, the microfractures in the Jurassic shale can be divided into diagenetic microfractures and structural microfractures according to the cause of formation.…”

Section: Resultsmentioning

confidence: 97%

“…The pores can exist both in the skeletons of clay minerals and in large deposits of mineral crystals (Desbois, Urai, & Kukla, ). The scanning electron microscopy results illustrate that many clastic particles (e.g., quartz and feldspar) with both regular and irregular shapes are packaged between the sheet and plate clay minerals of the mud shale samples; these clastic particles can form pores and combine with the surrounding clay minerals (Figure a; J. J. Li, Yin, et al, ; Takehiko, Osamu, & Toshiro, ; P. F. Wang et al, ; P. F. Zhang et al, ). The diameters of these pores are larger and can reach the micron scale.…”

Section: Resultsmentioning

confidence: 98%

“…OM pores are intrapores found within OM. The thermal maturation must reach an R o level of approximately 0.6% or higher before OM pores begin to develop (J. J. Li, Yin, et al, ; Robert, Robert, Stephen, & Ursula, ; P. F. Wang et al, ; M. Wang, Sherwood, et al, ; M. Wang, Wilkins, et al, ; P. F. Zhang et al, ), which, according to Dow (), is the beginning of peak oil generation. At levels of maturity less than 0.6% R o , OM pores are absent or extremely rare (Robert et al, ).…”

Section: Resultsmentioning

confidence: 99%

“…The thermal maturation must reach an R o level of approximately 0.6% or higher before OM pores begin to develop (J. J. Li, Yin, et al, 2015;Robert, Robert, Stephen, & Ursula, 2012; P. F. Wang et al, 2016;M. Wang, Sherwood, et al, 2015;P.…”

Section: Secondary Poresmentioning

confidence: 99%

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Geochemical and geological characteristics of the Jurassic continental black shale in the Southwestern Depression of Tarim Basin

Jiang

Liu

et al. 2018

Geological Journal

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Although Jurassic continental black shale within the Southwestern Depression of Tarim Basin (SDT) have received renewed attention during the past few years due to their potential to be prospected for shale gas, studies on shale characteristics remain rare. In this study, 31 black shale core samples were collected from a well (Buya‐1) drilled recently in the Hetian Sag of the southern SDT, and their geochemical, petrographical, mineralogical, petrophysical, and pore structural characteristics were determined through a series of tests. The results indicate that the black shale has high and variable total organic carbon (TOC) contents ranging between 0.1% and 17.0% (average 3.2%), is dominated by Type III kerogen (gas‐prone), and is in a mature to high‐mature stage. The shale is mainly composed of quartz, clay, and feldspar with mean contents of 40.0% (range = 15.0–72.0%), 51.0% (range = 25–77%), and 5.5% (range = 1–13.0%), respectively. The pore spaces are composed of primary pores, secondary pores, and microfractures. The mean sorbed gas content of the shale is approximately 2.4 m3/t, and the TOC is significantly positively and linearly correlated with the adsorbed gas capacity. The results show that the Jurassic continental shale in the SDT is very favourable for the formation of a large shale gas play, and the middle segment of the Jurassic shale is the most favourable target layer for shale gas exploration due to its greater gas generation capacity, higher mineralogical brittleness, larger gas storage space, and greater gas sorption capacity. This study is significant in guiding subsequent shale gas exploration and development in the Jurassic, SDT, and also is a reference for identifying favourable exploration targets of shale gas resource in other continental basins.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Secondary Poresmentioning

confidence: 99%

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Geochemical and geological characteristics of the Jurassic continental black shale in the Southwestern Depression of Tarim Basin

Jiang

Liu

et al. 2018

Geological Journal

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“…Gao and Hu [33] found that Barnett shale has low pore connectivity by conducting imbibition experiments. A number of previous researchers, Ji et al [34,35], Wang et al [36,37], Tang et al [38][39][40], and Chen et al [41], indicated that organic matter provided most of the connected pores and that the network consisting of interconnected organic pores, microcracks, and bedding plane provided the main percolation pathway of shale gas. The accumulation pattern was deduced in the comprehensive consideration of previous studies and the experimental results, as well as related tectonism (Figure 6).…”

Section: Shale Gas Accumulation Patternmentioning

confidence: 99%

Lateral Percolation and Its Effect on Shale Gas Accumulation on the Basis of Complex Tectonic Background

et al. 2018

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As a result of complex tectonic background, shale gas in China exhibits differential enrichment. Choosing a favorable exploration target accurately is a crucial problem to be solved. In this study, the tests show that there is a superior transportation pathway within shale layer. Gas in the shale layer percolates much more in the direction parallel to the plane. Therefore, the accumulation pattern of shale gas indicates a complex tectonic background. Gas in the lower part of the structure diffuses and percolates in the vertical direction into the surrounding rock. Most gas percolates towards the high part of the structure in the direction parallel to the plane. When the shale was exposed, gas percolated along the parallel direction into the air. In the case of fracture development, if there is a reverse fault, gas would be enriched in the footwall. However, if there is an unsealed fault, it would become a pathway for gas migration. The above accumulation pattern was proved in several Areas. Also, this research presented a basis of evaluation units division. According to the buried depth, fractures, and structural position, Xiuwu Basin was divided into five evaluation units and Unit A3 is the most favorable exploration target.

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Connectivity of organic matter pores in the Lower Silurian Longmaxi Formation shale, Sichuan Basin, Southern China: Analyses from helium ion microscope and focused ion beam scanning electron microscope

et al. 2022

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As one of the most important energy sources in the world today, shale gas has attracted extensive research. Numerous scholars agreed that the organic matter (OM) pores in shale provide the main space which benefits effective gas occurrence. However, the connectivity provided by OM pores is more important in the development process than their reservoir properties. A comprehensive portrayal of the 3D connectivity of the OM pores is elaborated in this study. The Lower Silurian Longmaxi shale samples were selected as the research subject.The shale samples are subjected to focused ion beam scanning electron microscope, helium ion microscope observation experiments, 2D microscopic characterization of OM pores, and 3D segmentation extraction. The results indicate that the connectivity of shale is mainly contributed by OM pores. The OM pores have the advantageous structural characteristics of large number per unit area, evenly distributed, regular pore morphology, and large pore size relative to the mineral matrix pores. The OM pores structure in shale is complex with a network structure of small pores nested in large pores, which can increase the adsorption capacity of gas. Besides, the small pores nested in large pores can act as a throat to significantly improve the connectivity. OM pores in the pyrobitumen are interconnected in 3D space, providing the main channels for gas percolation in the shale reservoir.

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Pore structure characterization for the Longmaxi and Niutitang shales in the Upper Yangtze Platform, South China: Evidence from focused ion beam–He ion microscopy, nano-computerized tomography and gas adsorption analysis

Cited by 128 publications

References 52 publications

Geochemical and geological characteristics of the Jurassic continental black shale in the Southwestern Depression of Tarim Basin

Geochemical and geological characteristics of the Jurassic continental black shale in the Southwestern Depression of Tarim Basin

Lateral Percolation and Its Effect on Shale Gas Accumulation on the Basis of Complex Tectonic Background

Connectivity of organic matter pores in the Lower Silurian Longmaxi Formation shale, Sichuan Basin, Southern China: Analyses from helium ion microscope and focused ion beam scanning electron microscope

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