Characterization of shale gas enrichment in the Wufeng Formation–Longmaxi Formation in the Sichuan Basin of China and evaluation of its geological construction–transformation evolution sequence

He, Zhanxiang; Hu, Zhao; Nie, Haikuan; Li, Shuangjian; Xu, Jin

doi:10.1016/j.jnggs.2017.03.002

Cited by 50 publications

(34 citation statements)

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“…Surrounded by the Hubei-Hunan-Guizhou Fold Belt on the east, the Longmenshan Fold Belt on the west, the Micang Uplift and Dabashan Fold Belt sitting on the north, and the Emei-Liangshan Fold Belt on the south, the basin can be divided into three tectonic regions and six sublevel tectonic units by the Huayingshan and Longquanshan anticlines [34] (Figure 1). Several tectonic movements occurred in the Sichuan Basin which in chronological order are the Caledonian (Cambrian-Silurian), Hercynian (Devonian-Permian), Indosinian (Triassic), Yanshanian (Jurassic-Late Cretaceous), and Himalayan (Paleogene-Quaternary) orogenies [34][35][36]. Sedimentary sequences of the basin are relatively complete, which include the Middle-Upper Proterozoic, Paleozoic, Mesozoic, and Cenozoic strata.…”

Section: Geological Settingmentioning

confidence: 99%

Coevolutionary Dynamics of Organic-Inorganic Interactions, Hydrocarbon Generation, and Shale Gas Reservoir Preservation: A Case Study from the Upper Ordovician Wufeng and Lower Silurian Longmaxi Formations, Fuling Shale Gas Field, Eastern Sichuan Basin

et al. 2020

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Shale gas deposits are self-sourced, self-accumulating, and self-preserving in the Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation of the Fuling Shale Gas Field in the eastern Sichuan Basin. They were both seemingly mixed by secondary oil cracking and kerogen cracking gases during the high maturation window. The reservoir space primarily consists of mineral pores and organic matter (OM) pores, and the shale gas was mainly trapped by a high-pressure system. In this study, the Fuling O3w-S1l Shale Gas Field in the eastern Sichuan Basin was used as a case study to discuss the coevolutionary process and organic-inorganic interactions of hydrocarbon generation, accumulation, and preservation. The results indicate that the processes and mechanisms of organic-inorganic interactions and coevolution of hydrocarbon generation and reservoir preservation are quite different among the shale graptolite zones (GZ) with respect to hydrocarbon generation, types and characteristics of shale gas reservoirs, seal characteristics, and their spatiotemporal relations. In the WF2-LM4 GZ, the favorable OM, biogenic authigenic quartz and organic-inorganic interactions are highly coupled, leading to the high level of coevolution demonstrated within the field, as well as to the favorable conditions for shale gas accumulation. Conversely, the overlying LM5-LM8 GZ seemingly exhibits early densification and late charge and has a reverse mode of reservoir development (i.e., low degree of coevolution). These two coevolutionary processes were conducive to the development of a high degree of spatiotemporal matching between the reservoir (i.e., WF2-LM4 GZ) and the seal (i.e., LM5-LM8 GZ). This is due to underlying differences in their coevolutionary histories. The synthetic work presented here on the coevolutionary processes and mechanisms of formation for organic-inorganic interactions and hydrocarbon generation and reservoir preservation reveals insights into the driving mechanisms of shale gas enrichment, providing a basis for effectively predicting favorable enrichment intervals for shale gas worldwide.

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Section: Geological Settingmentioning

confidence: 99%

Coevolutionary Dynamics of Organic-Inorganic Interactions, Hydrocarbon Generation, and Shale Gas Reservoir Preservation: A Case Study from the Upper Ordovician Wufeng and Lower Silurian Longmaxi Formations, Fuling Shale Gas Field, Eastern Sichuan Basin

et al. 2020

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“…The Sichuan Basin has experienced a number of complex tectonic movements, including the Caledonian, Hercynian, Indosinian, Yanshanian (Jurassic-Late Cretaceous) and Himalayan movement. The Yanshanian movement controls the differential tectonic evolution of the eastern and western regions, which has had a major impact on the distribution, burial depth and preservation conditions of marine shale strata (He et al, 2017a). The Mesozoic and Cenozoic tectonic uplifts in the southeast of the Sichuan Basin are characterized by E-W blocks, N-S belts, and progressive deformation (Li et al, 2012).…”

Section: Regional Tectonic Backgroundmentioning

confidence: 99%

“…In terms of the porosity sensitivity and the porosity preservation under in situ pressure conditions, the eastern Sichuan Basin has a high degree of tectonic deformation, an early deformation period and relatively low pressure maintenance (He et al, 2017a). The Wufeng-Longmaxi shale in the eastern Sichuan Basin is strongly compacted, and its physical sensitivity is lower than that in the highultrahigh pressure area.…”

Section: Physical Properties (1) Porositymentioning

confidence: 99%

“…14). The eastern Sichuan Basin is greatly affected by the deformation resulting from the Yanshanian movement (Li et al, 2012;He et al, 2017a), and the shale reservoir is subject to different degrees of pressure relief. The pressure relief results in significantly deteriorated physical properties of the organic-rich argillaceous shale, silty shale and organic-lean argillaceous shale (with a lower anticompaction capacity); these shale plays gradually evolved into direct cap rocks in the eastern Sichuan Basin (Fig.…”

Section: Differential Evolution Of Reservoirsmentioning

confidence: 99%

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Differential Characteristics of the Upper Ordovician‐Lower Silurian Wufeng‐Longmaxi Shale Reservoir and its Implications for Exploration and Development of Shale Gas in/around the Sichuan Basin

Wang

Long

et al. 2019

Acta Geologica Sinica (Eng)

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The Upper Ordovician Wufeng‐Lower Silurian Longmaxi shale is widely distributed in the Sichuan Basin and its periphery, which is the key stratum for marine shale gas exploration and development (E&D) in China. Based on sedimentary environment, material basis, storage space, fracability and reservoir evolution data, the reservoir characteristics of the Wufeng‐Longmaxi shale and their significance for shale gas EE&D are systematically compared and analyzed in this paper. The results show that (1) the depocenter of the Wufeng (WF)‐Longmaxi (LM) shale gradually migrates from east to west. The high‐quality shale reservoirs in the eastern Sichuan Basin are mainly siliceous shales, which are primarily distributed in the graptolite shale interval of WF2‐LM5. The high‐quality reservoirs in the southern Sichuan Basin are mainly calcareous‐siliceous and organic‐rich argillaceous shales, which are distributed in the graptolite shale interval of WF2‐LM7. (2) Deep shale gas (the burial depth >3500 m) in the Sichuan Basin has high‐ultrahigh pressure and superior physical properties. The organic‐rich siliceous, calcareous‐siliceous and organic‐rich argillaceous shales have suitable reservoir properties. The marginal area of the Sichuan Basin has a higher degree of pressure relief, which leads to the argillaceous and silty shales evolving into direct cap rocks with poor reservoir/good sealing capacity. (3) Combining shale gas exploration practices and impacts of lithofacies, depth, pressure coefficient and brittle‐ductile transition on the reservoir properties, it is concluded that the favorable depth interval of the Wufeng‐Longmaxi shale gas is 2200∼4000 m under current technical conditions. (4) Aiming at the differential reservoir properties of the Wufeng‐Longmaxi shale in the Sichuan Basin and its periphery, several suggestions for future research directions and EE&D of shale gas are formulated.

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“…To date, China has made significant progress in the research and development of shale gas [3][4][5][6][7]. In Jiaoshiba Chongqing, the first large-scale shale gas field in China was built and has reached 100 billion cubic meters [8].…”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Morphology and Connectivity of Organic Pores in Shale from the Wufeng and Longmaxi Formations at the Southeast Sichuan Basin in China

Jiang

Jin

et al. 2021

Geofluids

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Organic pores play an important role in shale reservoirs. Organic pores occur where shale gas was produced and accumulated. However, there is little scientific understanding of the distribution and connectivity of organic pores. Organic pore types and their structural characteristics were studied using a total organic carbon (TOC), thin section, focused ion beam scanning electron microscope (FIB-SEM), and nano-CT. The samples were from the Wufeng Formation in the Upper Ordovician and Longmaxi Formations from the lower Silurian. The results show that organic matter is mainly concentrated in the Wufeng Formation and the bottom of the Longmaxi Formation and that the middle and upper parts of the Longmaxi Formation contain a low amount of organic matter. The shale of the Wufeng-Longmaxi Formation has high maturity, and its organic pores are well developed. There are three types of organic pores: algae, graptolite, and pyrobitumen pores. The pore connectivity of shale with a high organic content is better than that of shale with a low organic content. The volume of the organic pores accounts for more than 50% of the volume of the organic matter. Majority of the organic pores have an aperture smaller than 100 nm and are round, nearly circular, and elliptical in morphology. Most of the organic pores in a shale formation are developed in pyrobitumen, and most of the larger organic pores are concentrated at the center of solid pyrobitumen. The organic pores in pyrobitumen have the best connectivity and are the most favorable reservoir spaces and migration channels for shale gas, which is a crucial point of reference for future research of shale gas.

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Characterization of shale gas enrichment in the Wufeng Formation–Longmaxi Formation in the Sichuan Basin of China and evaluation of its geological construction–transformation evolution sequence

Cited by 50 publications

References 3 publications

Coevolutionary Dynamics of Organic-Inorganic Interactions, Hydrocarbon Generation, and Shale Gas Reservoir Preservation: A Case Study from the Upper Ordovician Wufeng and Lower Silurian Longmaxi Formations, Fuling Shale Gas Field, Eastern Sichuan Basin

Coevolutionary Dynamics of Organic-Inorganic Interactions, Hydrocarbon Generation, and Shale Gas Reservoir Preservation: A Case Study from the Upper Ordovician Wufeng and Lower Silurian Longmaxi Formations, Fuling Shale Gas Field, Eastern Sichuan Basin

Differential Characteristics of the Upper Ordovician‐Lower Silurian Wufeng‐Longmaxi Shale Reservoir and its Implications for Exploration and Development of Shale Gas in/around the Sichuan Basin

Three-Dimensional Morphology and Connectivity of Organic Pores in Shale from the Wufeng and Longmaxi Formations at the Southeast Sichuan Basin in China

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