Lithofacies classification and its effect on pore structure of the Cambrian marine shale in the Upper Yangtze Platform, South China: Evidence from FE-SEM and gas adsorption analysis

Wang, Pengfei; Jiang, Zhenxue; Yin, Li; Chen, Lei; Li, Zhuo; Zhang, Chen; Li, Tingwei; Pu, Huayan

doi:10.1016/j.petrol.2017.06.011

Cited by 78 publications

(50 citation statements)

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“…The Lower Yangtze Platform, which is located in the eastern part of South China and along the Lower Yangtze Valley, is a large sedimentary basin covering a total area of approximately 36 × 10 4 km 2 (Du, Zhang, et al, ; Pan et al, ; Wang et al, ). It is bounded by the Tan‐lu Fault Zone in the north‐west and the Xuefeng–Jiangnan Fault Zone in the south‐east, and four tectonic units have been identified, namely, Qiantang Depression, Jiangnan Uplift, Nanjing Depression, and Subei Slope (Du, Song, et al, ; Figure a).…”

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

“…Thus far, most research and exploration breakthroughs for shale gas in China have focused on the Lower Silurian shale of the Middle and Upper Yangtze regions (Dai et al, ; Jiang et al, ; Li, Jiang, Zheng, Bi, & Chen, ; Wang et al, ; Yan et al, ; Zou et al, , , ). As a part of the Yangtze Platform, the neighbouring Lower Yangtze region has attracted much less interests in searching shale gas potentials (but see Du et al, ).…”

Section: Introductionmentioning

confidence: 99%

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The Lower Yangtze area: A next shale gas block for China? Preliminary potential assessment from some geology and organic geochemistry information

Chen

et al. 2019

Geological Journal

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In the last several years, the massive success of the Fuling shale gas field in south‐western China has shown great potential in finding giant shale gas fields in the Upper Yangtze area, and it has also attracted the increasing attention from geologists to find more shale gas reservoirs around the world. However, there is still a great dispute as to whether the neighbouring Lower Yangtze area is a next potential shale gas block in China. In this study, we evaluate preliminarily the shale gas potentials of five important sets of marine shales based on systematic analyses for the sedimentary environment, thickness, total organic carbon (TOC), thermal maturity, and other organic geochemistry parameters of both geological records from outcrops and wells in the Lower Yangtze area. The first two sets of marine shales occur in the Lower Cambrian and the Ordovician, and they all are of over–high organic maturity due to strong effects from regional tectonic movements and thus have poor potential. Although the Lower Silurian shales are widely distributed in the Lower Yangtze region, a terrigenous delta, a low amount of organic matter (TOC < 1.2%), and late tectonic activity together created unfavourable conditions for the generation and accumulation of the Lower Silurian shale gas. The Permian black shales occur in the Middle and Upper Permian. Several proxies, such as the appropriate maturity (vitrinite reflectance Ro of approximately 2.0%), abundant organic matter (TOC of approximately 4 wt%), good total hydrocarbon potential (S1 + S2), and high level of hydrocarbon conversion have resulted in good conditions for shale gas generation. However, the relative thinness (only 30 m), severe tectonic modification, and regional cap rock are not favourable for shale gas preservation. The Lower Yangtze area therefore is not an excellent block for shale gas exploration compared to its neighbouring Upper Yangtze area. However, in some areas with less structural deformation, the possibility of finding shale gas reservoirs cannot be ruled out, especially for the Permian shales, which had a greater opportunity to generate and accumulate shale gas than the other marine shales. In addition, for new shale gas exploration breakthroughs in the future, structural studies are essential in offering better understanding of the preservation conditions in the Lower Yangtze area.

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Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Lower Yangtze area: A next shale gas block for China? Preliminary potential assessment from some geology and organic geochemistry information

Chen

et al. 2019

Geological Journal

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“…4.2, is also likely to influence the fractal dimension through impacting pore throat structures. [48][49][50] Therefore, pore-throat structure parameters and mineral compositions illustrated in Fig. 9 can explain the way rock mineral compositions impact pore-throat structures.…”

Section: Effects Of Mineral Compositions On Pore-throat Structuresmentioning

confidence: 99%

Pore-Throat Structure and Fractal Characteristics of Shihezi Formation Tight Gas Sandstone in the Ordos Basin, China

et al. 2018

Self Cite

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In order to better understand the impact of fractal features of pore-throat structures on effective physical properties of tight gas sandstones, this paper carried out constant-rate mercury ‡ ‡ Corresponding authors. This is an Open Access article published by World Scientific Publishing Company. It is distributed under the terms of the Creative Commons Attribution 4.0 (CC-BY) License. Further distribution of this work is permitted, provided the original work is properly cited. 1840005-1Fractals 2018.26. Downloaded from www.worldscientific.com by 13.66.222.141 on 04/01/19. Re-use and distribution is strictly not permitted, except for Open Access articles. H. Huang et al.injection tests, gas-water permeability analyses, helium-based porosity and nitrogen pulse decay permeability measurements, and SEM and casting thin-section analyses on 20 sandstone samples of the Shihezi Formation from 16 wells of the Sulige Gas Field in the Ordos Basin, China. The fractal dimensions of pores corresponding to two pore radius ranges, namely fractal dimensions D p2 and D p3 , and those of throats also corresponding to two throat radius ranges, namely fractal dimensions D t1 and D t2 , were then calculated using the constant-rate mercury injection data. Fractal dimensions D p2 and D p3 are negatively correlated with the average pore radius and pore volume as well as quartz content, and they are positively related to contents of clay minerals and lithic fragments. Compared with pore fractal dimensions, throat fractal dimensions have lower correlations with throat structural parameters, and show vague relations with mineral compositions. Although the effects imposed by mineral compositions upon throat structures are similar to those upon pore structures, the flake-like and curved shapes of throats result in irregularity of fractal dimensions. Tight gas sandstones, with smaller fractal dimensions D p2 and D p3 , have larger effective porosity, indicating that more gas volumes can be replaced by liquids. As for tight gas sandstones with lower fractal dimensions D p3 and D t2 , the effective gas permeability is relatively high. In such cases, gas can flow more easily through the reservoir.

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“…Undoubtedly, pore characteristics play important roles in shale oil and gas exploration as well as development Yang et al, 2015b;Zhang et al, 2015b;Wang et al, 2016a;Wang et al, 2014Wang et al, , 2016bChen et al, 2017). Much research has been published on fracture and micropore types, distribution, and morphology, as well as the factors that control shale development (Huang et al, 2013a, b;Chen et al, 2015;Chen et al, 2016;Cao et al, 2016;Clarkson et al, 2016;Ran et al, 2016;Wang et al, 2017;Wu et al, 2020). Slatt and O'Brien (2011) defined and identified porous floccules, organopores, fecal pellets, fossil fragments, intraparticle pores, microchannels, and microfractures present in the Barnett and Woodford shales.…”

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confidence: 99%

Characterization of a Lacustrine Shale Reservoir and the Evolution of its Nanopores: A Case Study of the Upper Cretaceous Qingshankou Formation in the Songliao Basin, Northeastern China

Zhang

Liu

et al. 2020

Acta Geologica Sinica (Eng)

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The Songliao Basin is one of the most important petroliferous basins in northern China. With a recent gradual decline in conventional oil production in the basin, the exploration and development of unconventional resources are becoming increasingly urgent. The Qingshankou Formation consists of typical Upper Cretaceous continental strata, and represents a promising and practical replacement resource for shale oil in the Songliao Basin. Previous studies have shown that low‐mature to mature Qingshankou shale mainly preserves type I and type II1 organic matter, with relatively high total organic carbon (TOC) content. It is estimated that there is a great potential to explore for shale oil resources in the Qingshankou Formation in this basin. However, not enough systematic research has been conducted on pore characteristics and their main controlling factors in this lacustrine shale reservoir. In this study, 19 Qingshankou shales from two wells drilled in the study area were tested and analyzed for mineral composition, pore distribution and feature evolution using X‐ray diffraction (XRD), scanning electron microscopy (SEM), low‐pressure nitrogen gas adsorption (N2‐GA), and thermal simulation experiments. The XRD results show that clay, quartz, and feldspar are the dominant mineral constituents of Qingshankou shale. The clay minerals are mostly illite/smectite mixed layers with a mean content of 83.5%, followed by illite, chlorite, and kaolinite. There are abundant deposits of clay‐rich shale in the Qingshankou Formation in the study area, within which many mineral and organic matter pores were observed using SEM. Mineral pores contribute the most to shale porosity; specifically, clay mineral pores and carbonate pores comprise most of the mineral pores in the shale. Among the three types of organic matter pores, type B is more dominant the other two. Pores with diameters greater than 10 nm supply the main pore volume; most are half‐open slits and wedge‐shaped pores. The total pore volume had no obvious linear relationship with TOC content, but had some degree of positive correlation with the content of quartz + feldspar and clay minerals respectively. However, it was negatively correlated with carbonate mineral content. The specific surface area of the pores is negatively related to TOC content, average pore diameter, and carbonate mineral content. Moreover, it had a somewhat positive correlation with clay mineral content and no clear linear relationship with the content of quartz + feldspar. With increases in maturity, there was also an increase in the number of carbonate mineral dissolution pores and organic matter pores, average pore diameter, and pore volume, whereas there was a decrease in specific surface area of the pores. Generally, the Qingshankou shale is at a low‐mature to mature stage with a TOC content of more than 1.0%, and could be as thick as 250 m in the study area. Pores with diameters of more than 10 nm are well‐developed in the shale. This research illustrates that there are favorable condi...

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Lithofacies classification and its effect on pore structure of the Cambrian marine shale in the Upper Yangtze Platform, South China: Evidence from FE-SEM and gas adsorption analysis

Cited by 78 publications

References 57 publications

The Lower Yangtze area: A next shale gas block for China? Preliminary potential assessment from some geology and organic geochemistry information

The Lower Yangtze area: A next shale gas block for China? Preliminary potential assessment from some geology and organic geochemistry information

Pore-Throat Structure and Fractal Characteristics of Shihezi Formation Tight Gas Sandstone in the Ordos Basin, China

Characterization of a Lacustrine Shale Reservoir and the Evolution of its Nanopores: A Case Study of the Upper Cretaceous Qingshankou Formation in the Songliao Basin, Northeastern China

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