Advantageous shale lithofacies of Wufeng Formation-Longmaxi Formation in Fuling gas field of Sichuan Basin, SW China

Wu, Lanyu; Hu, Dongfeng; Lu, Yongchao; Liu, Ruobing; Liu, Xiaofeng

doi:10.1016/s1876-3804(16)30024-6

Cited by 80 publications

(38 citation statements)

References 11 publications

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“…We can find that the Niutitang formation shale can be identify as mixed siliceous (S-2) or clay-rich siliceous (S-3) shale lithofacies (Figure 5). Compared with Barnett shale and others (Wu et al., 2016), the content of siliceous is too much and clay minerals are relatively low in the study area. However, the brittle mineral content of shale in the study area is generally high and the brittleness index (I) of HY1 and CY1 well are 0.52 and 0.59 on average respectively, which is favorable conditions for fracturing and increasing shale gas production (Gale et al., 2007).…”

Section: Resultscontrasting

confidence: 73%

“…Based on the three end members of mineral composition, we can classify four mainly shale lithofacies types: siliceous shale lithofacies (S), calcareous shale lithofacies (C), argillaceous shale lithofacies (CM), and mixed shale lithofacies (M). Each type can further classify into four types, and 16 types in all (Wu et al, 2016). We can find that the Niutitang formation shale can be identify as mixed siliceous (S-2) or clay-rich siliceous (S-3) shale lithofacies ( Figure 5).…”

Section: Lithology and Mineralsmentioning

confidence: 99%

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Characterization of pore microstructure and methane adsorption of organic-rich black shales in northwestern Hunan, South China

Huang

Dong

Hursthouse

et al. 2019

Energy Exploration & Exploitation

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The gas adsorption of shale is one of the most important factors influencing shale gas accumulation and production. Different from other shale gas fields, the shale in Northwestern Hunan province with strong structural deformation has especially high portion of adsorbed gas. The adsorption abilities of shale reservoir play a significant role in the success of exploration and production of shale gas in Northwestern Hunan. Therefore, based on many experiments including field emission scanning electron microscopy, N2/CO2 adsorption, excess CH4 adsorption with constant temperature and others, this paper found that: (1) the shale pores were identified with mineral matrix pores, organic-matter pores and fracture pores, and the pores can be further classified according to their shape features and forming mechanism; (2) after analyses of the distribution of the pore size, mesoporous is the largest contributor and widely distributed, and micropores provide more contribution on surface area but limited contribution to pore volume. Meanwhile, depth has little effect on the properties of shale reservoirs; (3) based on the fractal geometry theory, surface roughness is positively correlated to microstructure irregularity, which means the effects between the gas adsorption by Van der Waals force and by multilayer or capillary condensation in single pore system are consistent during the N2 adsorption process. (4) The abilities of gas storage are apparently sensitive to the surface roughness of shale pores and nonsensitive to microstructure irregularity. Total organic carbon has strong positive correlation with the surface roughness, specific surface area, total pore volume, and Langmuir volume, which means TOC can improve the adsorption of shale reservoir in many ways. Pyrite can offer much contribution to the ability of gas adsorption.

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Section: Resultscontrasting

confidence: 73%

Section: Lithology and Mineralsmentioning

confidence: 99%

Characterization of pore microstructure and methane adsorption of organic-rich black shales in northwestern Hunan, South China

Huang

Dong

Hursthouse

et al. 2019

Energy Exploration & Exploitation

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“…In recent years, many scholars have classified lithofacies based on a ternary diagram analysis of siliceous (quartz and feldspar), carbonate, and clay minerals (Hickey and Henk, 2007;Wang Y.M. et al, 2016b;Wu et al, 2016). Measurement results show that the Longmaxi Formation samples from the YS and N wells can be divided mainly into four ( Fig.…”

Section: Lithofacies Typementioning

confidence: 99%

“…Shale lithofacies with high TOC, high porosity and high brittle mineral content are generally regarded as the most favorable lithofacies in shale gas exploration (Wu et al, 2016). The Longmaxi Formation has three favorable lithofacies: S-2, M-2 and S-3.…”

Section: Lithofacies Typementioning

confidence: 99%

Relationship Between Electrical Properties and Sedimentary Environment of the Longmaxi Formation Shale, Southern Sichuan

Yang

Zhang

Wang

et al. 2020

Acta Geologica Sinica (Eng)

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The Lower Silurian Longmaxi Formation in the south of Sichuan is a key player in the exploration and development of shale gas in China. Due to a highly complex topographic area, electromagnetic methods (EM) become important exploration means in this area. Many studies have been conducted on the shale mineral composition and electrical properties of shale, however, the correlation between sedimentary environments and the electrical properties of shale remain poorly understood. The electrical properties and sedimentary environment of the organic-rich shale of the Longmaxi Formation have been studied by means of X-ray diffraction, organic geochemistry, scanning electron microscopy and complex resistivity measurements. The discovered high quartz content of the Longmaxi Formation shale results in low resistivity. Deep-water shelf biogenic quartz contributes lower resistivity more than that of shallow-water terrigenous quartz. The deep-water anoxic and organic sedimentary environment led to major enrichment of pyrite, leading to a high polarization effect in shale. We present the correlation between the lithofacies types and electrical properties of Longmaxi Formation. The mixed siliceous shale lithofacies is the most favorable among the three lithofacies, which is characterized by high total organic carbon (TOC) content, high brittleness mineral content, high polarization and low resistivity ("three high and one low"). This feature is an effective identification of shale gas reservoirs by electromagnetic prospecting. Our study can provide constraints on electrical parameters of rocks for electromagnetic "sweet spot" exploration of shale gas, and so this has important geological significance to shale gas exploration and development.

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“…Above all, Xinkailing-formation shale is characterized by a high brittleness index and can easily be fractured. Research has classified the shale in the Fuling area into four lithofacies (major classes) and 16 lithofacies (minor classes) [44] based on a 3-end-mumber diagram analysis of the silicon minerals, carbonate minerals, and clay minerals, and has found that mixed siliceous shale and clay-rich siliceous shale were most conducive to formation of lithofacies. Applying the 3-end-mumber diagram analysis to Xinkailing-formation shale, results showed that clay-rich siliceous shale contained most lithofacies (as shown in Figure 10).…”

Section: Mineral Composition and Lithofaciesmentioning

confidence: 99%

A New Insight into Shale-Gas Accumulation Conditions and Favorable Areas of the Xinkailing Formation in the Wuning Area, North-West Jiangxi, China

Li¹,

Zeng²,

Wang³

et al. 2017

Energies

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Abstract:In north-west Jiangxi, China, most shale-gas exploration has been focused on the Lower Cambrian Hetang and Guanyintang formations, whereas the Upper Ordovician Xinkailing formation shale has been ignored for years due to heavy weathering. This study systematically analyzed gas source conditions, reservoir conditions and gas-bearing ability in order to reveal the shale-gas accumulation conditions of the Xinkailing formation. The results show that the Xinkailing formation is characterized by thick deposition of black shale (10-80 m), high organic content (with total organic carbon between 1.18% and 3.11%, on average greater than 2%), relatively moderate thermal evolution (with vitrinite reflectance between 2.83% and 3.21%), high brittle-mineral content (greater than 40%), abundant nanopores and micro-fractures, very good adsorption ability (adsorption content between 2.12 m 3 /t and 3.47 m 3 /t, on average about 2.50 m 3 /t), and strong sealing ability in the underlying and overlying layers, all of which favor the generation and accumulation of shale gas. The Wuning-Lixi and Jinkou-Zhelin areas of the Xinkailing formation were selected as the most realistic and favorable targets for shale-gas exploration and exploitation. In conclusion, the Wuning area has great potential and can provide a breakthrough in shale gas with further investigation.

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Advantageous shale lithofacies of Wufeng Formation-Longmaxi Formation in Fuling gas field of Sichuan Basin, SW China

Cited by 80 publications

References 11 publications

Characterization of pore microstructure and methane adsorption of organic-rich black shales in northwestern Hunan, South China

Characterization of pore microstructure and methane adsorption of organic-rich black shales in northwestern Hunan, South China

Relationship Between Electrical Properties and Sedimentary Environment of the Longmaxi Formation Shale, Southern Sichuan

A New Insight into Shale-Gas Accumulation Conditions and Favorable Areas of the Xinkailing Formation in the Wuning Area, North-West Jiangxi, China

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