Pore-structure characterisation of tectonically deformed shales: a case study of Wufeng-Longmaxi Formation in western Hunan Province, southern China

Li, Zhenwei; Jiang, Zhenxue; Liang, Zhikai; Yu, Hailong; Yang, Youdong

doi:10.1080/08120099.2019.1588168

Cited by 19 publications

(18 citation statements)

References 43 publications

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“…Shale deformation is classified in three main forms of brittle deformation, brittle-ductile deformation, and ductile deformation [36][37][38][39][40]. Whether it is brittle deformation or ductile deformation, as the deformation intensity increases, both microchannels and microfractures increase [37,38,40].…”

Section: Effect Of Tectonism On Porementioning

confidence: 99%

“…N 2 has different adsorption mechanisms under different pressure conditions, so the fractal dimension D 1 of the low pressure stage is usually used to indicate the surface roughness of the pore structure, while the fractal dimension D 2 of the high-pressure stage represents the irregularity of the pore structure [11,47,48]. The tectonism can change the relationship between the pores in the shale reservoir, making the pore system of the shale more complex [32,[36][37][38][39][40] 10 Geofluids weak deformation (Table 2 and Figure 12). The samples with strong deformation that always have a relatively large D 1 may be related to the mixing behavior of clay and OM.…”

Section: Effect Of Tectonism On Pore Fractalmentioning

confidence: 99%

“…The irregularity of pore structure has an important influence on the spatial geometrical dimension, pore heterogeneity, and interconnectivity [11,13,49]. And multiple tectonism has an important influence on the pore network, which makes the nm-μm scale interP gap particularly developed [37,40]. This also causes the shale with strong deformation to have a high D 2 .…”

Section: Geofluidsmentioning

confidence: 99%

“…Recently, some researchers have got down to notice natural tectonic deformed samples and conducted experiments to study the relationship between tectonism and shale composition and pore structure features through experiments [32,[36][37][38][39][40]. Ju et al made inner comparison among the material composition and pore characteristics of brittle deformation, ductile deformation, and brittleductile shale samples from various areas and found that brittle shear results in microfractures and large pores and thus has an impact on the desorption and percolation capability of shale gas; the ductile deformation increased the specific surface area and enhanced the adsorption capacity of deformed shale [36].…”

Section: Introductionmentioning

confidence: 99%

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Relationship between Tectonism and Composition and Pore Characteristics of Shale Reservoirs

et al. 2020

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Tectonism is one of the major controlling factors of shale gas accumulation and enrichment in China. To explore the relationship between tectonism and composition and pore characteristics of shale reservoirs, this research carried out mineralogy tests, organic geochemistry tests, field emission scanning electron microscopy (FE-SEM) experiments, and low-pressure gas adsorption (LPGA, N2 and CO2) experiments on the shale samples of various deformation intensities from Southwestern China. Based on the FE-SEM image analyses, it can be found that there are large differences in pore characteristics in shale samples with different deformation intensities. The samples with strong deformation have more organic pores, mainly related to the clay-organic aggregates and rigid grains. Tectonism can cause organic matter (OM) and clay minerals to be mixed or OM to fill in the clay layers, resulting in the retention of some organic pores. It is the presence of pressure shadows around the rigid grains that can resist tectonic extrusion and protect some organic pores. LPGA experiment results also show that micropore-specific surface areas and pore volumes of the samples with strong deformation are larger than those with weak deformation. The shale samples with strong deformation also have more microchannels and microfractures. Tectonism can also cause some micropores to become macropores; for example, tectonism can cause the rigid grains to slide and rotate, enlarging the dissolution pores at the edges of rigid grains. Shale samples with strong deformation have a smaller mesopore volume; but due to the presence of organic-clay aggregates, a larger mesopore-specific surface area embarks on these samples. According to fractal dimension calculations, it is found that in strong deformed shale, more multiple dimensions of the pore system tend to represent rougher pore surfaces and more irregular shapes. Besides, rougher pore surfaces are eager to provide more adsorption sites and enhance the adsorption capacity of the deformed shale. This study investigates the relationship between tectonism and composition and pore characteristics of shale reservoirs and may promote understanding of the accumulation of shale gas in highly deformed areas.

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Section: Effect Of Tectonism On Porementioning

confidence: 99%

Section: Effect Of Tectonism On Pore Fractalmentioning

confidence: 99%

Section: Geofluidsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Relationship between Tectonism and Composition and Pore Characteristics of Shale Reservoirs

et al. 2020

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“…Shale slip rheological deformation refers to a migration process of solid matter driven by a given tectonic stress. In this process, solid matter migrates and redistributes in a given direction from macro to micro to adapt to the new tectonic environment (Liang et al 2017;Li et al 2019). In the case of plastic strain, the organic-rich shale can be regarded as a solid rheology that undergoes shear rupture and deformation (Ju et al 2018;Ma et al 2019).…”

Section: A Types and Characteristics Of Slip Rheological Deformatimentioning

confidence: 99%

Influence of differential structural deformation on shale reservoirs: a case study of the lower Silurian Longmaxi Shale in north Guizhou, Southern China

Gu¹,

Xu³

et al. 2020

Geol. Mag.

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Southern China is affected by multi-stage tectonic activities, with strong fold deformation, complex fault systems and poor shale gas preservation conditions. Here, we used shale samples from the lower Silurian Longmaxi shale in the complex tectonic area of Southern China, to study the relationship between differential structural deformation, and pore structure and adsorption capacity. According to the deformation mechanism of the shale, it is further divided into brittle-slip rheological deformation (BD) and ductile-slip rheological deformation (DD). The results show that all micro-fractures can be observed under scanning electron microscopy in deformed shale samples, but in shale samples with different types of rheological deformation, the micro-fractures have large differences in scale, fracture length and lateral connectivity. The micro-fractures developed in DD shales are small in scale and short in fracture length, but have strong local connectivity. In contrast, brittle minerals are more developed in BD shales, and interlayer shearing has formed micro-fractures with large fracture length and good lateral connectivity, which is beneficial for later fracturing. In these two types of deformed shales, pores in organic matter are rare, and sporadic organic pores have small pore size and poor connectivity. The total pore volume (1.8–2.4 × 10−2 cm3 g–1) of BD shale samples is higher than that of DD shale samples (0.8–1.6 × 10−2 cm3 g–1). There is a positive correlation between total pore volume and quartz content. In addition, the specific surface area (12–18 m2 g–1) of DD shale samples is larger than that of BD shale samples (6–12 m2 g–1).

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Evolution Mechanism of Pore Structures of Organic-Rich Shale Under Tectonic Deformation: A Comparative Study Between Whole Rock and Kerogen Samples

Cheng,

Jiang,

et al. 2023

Nat Resour Res

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Pore-structure characterisation of tectonically deformed shales: a case study of Wufeng-Longmaxi Formation in western Hunan Province, southern China

Cited by 19 publications

References 43 publications

Relationship between Tectonism and Composition and Pore Characteristics of Shale Reservoirs

Relationship between Tectonism and Composition and Pore Characteristics of Shale Reservoirs

Influence of differential structural deformation on shale reservoirs: a case study of the lower Silurian Longmaxi Shale in north Guizhou, Southern China

Evolution Mechanism of Pore Structures of Organic-Rich Shale Under Tectonic Deformation: A Comparative Study Between Whole Rock and Kerogen Samples

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