Pore characteristics and evolution mechanism of shale in a complex tectonic area: Case study of the Lower Cambrian Niutitang Formation in Northern Guizhou, Southwest China

Sun, Wenjibin; Zuo, Yujun; Wu, Zhonghu; Líu, Hao; Zheng, Lujing; Wang, Hong; Shui, Yue; Lou, Yili; Xi, Shijun; Li, Taotao

doi:10.1016/j.petrol.2020.107373

Cited by 37 publications

(27 citation statements)

References 44 publications

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“…For the Southern Guizhou, the maximum paleoburial depth of the Niutitang shale is 5600 m, corresponding to an Eq-R o of 2.2% to 2.7% (Figure 14), similar to the Yichang shale samples. The maximum paleoburial depth of the Niutitang shale seems to be closely related to the paleostructure of the Southern Guizhou area, which is structurally located on the east wing of the Qianzhong paleouplift [42,45]. Due to the presence of the Qianzhong paleouplift, the maximum ancient burial depth of the Niutitang shale in Southern Guizhou is much shallower than its peers.…”

Section: Geofluidsmentioning

confidence: 94%

“…11 Geofluids (Figure 16). In the early Paleozoic and late Paleozoic, Southern Guizhou experienced many large-scale transgression events and formed two sets of black shales representing the Cambrian, the Upper Ordovician, and the Lower Silurian [41,42]. The bottom of the Niutitang Formation is gray siliceous shale, the middle and lower part is gray carbonaceous shale, the upper part is dark gray argillaceous dolomite and mudstone, and the top is dark gray limestone [43,44].…”

Section: Geofluidsmentioning

confidence: 99%

“…However, from the perspective of the Niutitang shale in Chongqing, its thermal maturity is much higher than that in the Jingyan, Yichang, and Guizhou regions, while there are no OM pores of the Niutitang shale in Chongqing. However, other parameters such as TOC content, mineral composition, and kerogen type of the Niutitang shale reservoirs in the four regions (Jingyan, Chongqing, Yichang, and Guizhou) have similar characteristics [2,6,7,40,42,[48][49][50][51]. Therefore, thermal maturity is the key factor to control the OM pore development.…”

Section: Geofluidsmentioning

confidence: 99%

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Slope Belts of Paleouplifts Control the Pore Structure of Organic Matter of Marine Shale: A Comparative Study of Lower Cambrian Rocks in the Sichuan Basin

et al. 2021

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Extensive exploration of the marine shale of the Niutitang Formation in south China has been conducted. However, exploration and development results have varied considerably in different areas. For example, the Niutitang shale in Jingyan City (Southwestern Sichuan Basin) produces a large amount of gas with a long period of stable production. In contrast, most development wells in the Niutitang shale in Chongqing City do not produce gas. Scanning electron microscopy images showed that the organic matter (OM) pore development in the Niutitang shale in Jingyan is abundant, large in size, and are well connected. In contrast, OM pores in the Niutitang shale in Chongqing are rarely observed. OM pore development of the Jingyan and Chongqing shales is mainly controlled by thermal maturity as shown by equivalent vitrine reflectance determinations. The moderate thermal maturity has resulted in the development of a large number of OM pores in the Niutitang shale in Jingyan, whereas the high thermal maturity of the Niutitang shale in Chongqing has led to the destruction of most of the OM pores. Due to the existence of ancient uplift, the shale was buried shallowly in the process of hydrocarbon generation evolution, and the shale avoided excessive thermal evolution and retained appropriate thermal maturity. In the Jingyan area, due to its location near the central uplift in the Sichuan Basin, the Niutitang shale deposited nearby avoided excessive evolution, and a large number of OM pores were retained in the reservoir.

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Section: Geofluidsmentioning

confidence: 94%

Section: Geofluidsmentioning

confidence: 99%

Section: Geofluidsmentioning

confidence: 99%

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Slope Belts of Paleouplifts Control the Pore Structure of Organic Matter of Marine Shale: A Comparative Study of Lower Cambrian Rocks in the Sichuan Basin

et al. 2021

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“…, c r and ϕ r . The mechanical parameters can be obtained from concrete tests [46][47][48]. σ 1 r can be obtained from Equation (14).…”

Section: Parameter Determination Of the Statistical Damage Constitutimentioning

confidence: 99%

The Statistical Damage Constitutive Model of the Mechanical Properties of Alkali-Resistant Glass Fiber Reinforced Concrete

2020

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Alkali-resistant glass fiber reinforced concrete (AR-GFRC) has greatly improved in terms of tensile strength, toughness, durability, and reduction of cracking, which has been proven by testing. However, the constitutive relationship of fiber reinforced concrete under complicated stress represents a complex theoretical problem. In order to investigate the microscopic damage evolution and failure mechanism of AR-GFRC, the meso-statistical damage theory, microcontinuum theory, and composite material theory were considered, and uniaxial tensile tests of two types of AR-GFRC were conducted. A new damage variable expression of the AR-GFRC was proposed, and the stress-strain curve was redefined by considering the residual strength based on experimental fitting parameters and statistical parameters. A Weibull distribution was assumed and a statistical damage constitutive model was developed of the deformation process of the AR-GFRC while considering the residual strength effect; detailed calculation methods to determine the mechanical and statistical parameters of the concrete were developed. The validation results show that the theoretical stress-strain curve of the constitutive model is in good agreement with the experimental curve and the trend is consistent.

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“…Generally speaking, shale pore development is mainly affected by thermal maturity, organic matter abundance, kerogen maceral and mineral content, as well as other factors [10][11][12][13][14][15]. The relationship between thermal evolution degree and pore structure characteristics has obvious stage characteristics, which means that the porosity increases when the Ro(vitrinite reflectance) of the Niutitang shale reservoir is between 0.6% and 3%, and the pore structure is well developed; however, when Ro is more than 3.5%, it is adverse to pore development, and can even destroy the original pore structure and eventually lead to the disappearance of the pores [10,16]. Some scholars have also proposed that organic pores and micro-cracks develop in large quantities in the high-mature to over-mature stage [11,12].…”

Section: Introductionmentioning

confidence: 99%

The Characteristics and Main Controlling Factors for the Formation of Micropores in Shale from the Niutitang Formation, Wenshuicun Section, Southwest China

Huang

et al. 2021

Energies

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The characteristics of shale micro-pore development and its main influencing factors have important theoretical guiding significance for shale gas exploration and resource evaluation. In order to clarify the micro-pore development characteristics of lower Cambrian shale and the main controlling factors of micro-pore development, we used the lower Cambrian Niutitang formation shale, in the Wenshuicun section of the Guizhou Province in southwest China. The micro-pore development characteristics of the shale in the region were studied by argon ion profile field emission scanning electron microscopy and a low-temperature liquid nitrogen adsorption and desorption experimental system. The relationship between micro-pore and kerogen maceral composition, total organic carbon (TOC) content and different mineral content was analyzed in combination with mineral and geochemical characteristics. Inorganic pores (clay mineral pores, dissolution pores and pyrite intergranular pores) and micro-fractures (clay mineral shrinkage crack, tectonic fractures and overpressure fractures) were the main type of pore developed in the shale of the Niutitang formation in the Wenshuicun section, and no organic pores had developed. The pore size of shale is usually 2–50 nm, accounting for 58.33% of shale pores, e.g. mesopores. Clay mineral content has an obvious positive correlation with macropore volume and average pore diameter, and an obvious negative correlation with micropore volume. In addition, the content of feldspar in brittle minerals has a strong negative correlation with macropore volume and average pore diameter, and a strong positive correlation with micropore volume and BET-specific surface area. TOC content and the content of different kerogen macerals have no obvious correlation with the development of shale micropores in this region. It is concluded that inorganic mineral composition is the main controlling factor of micro-pore development within lower Cambrian shale, and organic matter abundance and maceral content have little influence on the micro-pore development. This study provides a case study for the characteristics of micropores in lower Cambrian shale in China.

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Pore characteristics and evolution mechanism of shale in a complex tectonic area: Case study of the Lower Cambrian Niutitang Formation in Northern Guizhou, Southwest China

Cited by 37 publications

References 44 publications

Slope Belts of Paleouplifts Control the Pore Structure of Organic Matter of Marine Shale: A Comparative Study of Lower Cambrian Rocks in the Sichuan Basin

Slope Belts of Paleouplifts Control the Pore Structure of Organic Matter of Marine Shale: A Comparative Study of Lower Cambrian Rocks in the Sichuan Basin

The Statistical Damage Constitutive Model of the Mechanical Properties of Alkali-Resistant Glass Fiber Reinforced Concrete

The Characteristics and Main Controlling Factors for the Formation of Micropores in Shale from the Niutitang Formation, Wenshuicun Section, Southwest China

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