Influence of the Late Ordovician‐Early Silurian Paleoenvironment and Related Geological Processes on the Organic Matter Accumulation and Carbon Isotope Excursion

Zhang, Pengyuan; Wang, Yongli; Wei, Zhifu; Wang, Gen; Zhang, Ting; He, Wei; Ma, Xueyun; Ma, He; Wei, Jianteng; Zhu, Chenxi

doi:10.1029/2023pa004628

Cited by 5 publications

(6 citation statements)

References 176 publications

(386 reference statements)

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“…In the early Rhuddanian, upwelling and the influx of eutrophic water fostered the flourishing of siliceous organisms. Afterward, the terrigenous clastic flux continued to increase and maintained at a high level, while the biogenic silicon content progressively decreased and stabilized, particularly during the Aeronian period . The lower QCI value of the LMX shale provides evidence that the excess silicon is not derived from hydrothermal sources, as the QCI of hydrothermal-sourced silicon quartz typically exhibits extraordinarily high values (9.25–10.42, Liu et al).…”

Section: Resultsmentioning

confidence: 97%

“…Afterward, the terrigenous clastic flux continued to increase and maintained at a high level, while the biogenic silicon content progressively decreased and stabilized, particularly during the Aeronian period. 21 The lower QCI value of the LMX shale provides evidence that the excess silicon is not derived from hydrothermal sources, as the QCI of hydrothermal-sourced silicon quartz typically exhibits extraordinarily high values (9.25−10.42, Liu et al 15 ). This is also supported by the low values of Mn (mean: 0.030%), Fe/Ti (mean: 8.97), and high ratio of Al/(Al + Fe + Mn) (mean: 0.68) in the studied LMX shale.…”

Section: Characteristics and Control Factors Of Quartzmentioning

confidence: 99%

“…In contrast, montmorillonite illitization mainly occurs at temperatures ranging from 60 to 140 °C, and Q C has higher QCI values due to its occurrence at higher temperatures or later diagenetic stages, which can be attributed to the promoting effect of formation temperature on quartz crystallization. 17 Moreover, detrital particles from the provenance area, primarily composed of felsic igneous rocks, 21 are considered to have fixed properties, and their QCI value may even exceed 10. 14 The established burial evolution framework of the LMX shale, based on Qiu et al, 37 demonstrates that it experienced quick subsidence during the Middle-Late Silurian, and the Q B likely appeared before the oil generation window (Ro < 0.5%).…”

Section: Characteristics and Control Factors Of Quartzmentioning

confidence: 99%

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Quartz Crystallinity Characteristics and Their Effects on Shale Gas Reservoir Performance: A Case Study of the Deep Longmaxi Formation Shale in the Sichuan Basin, China

Feng,

Xiao,

Wang

et al. 2024

ACS Earth Space Chem.

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Quartz, as a pivotal constituent of shale, has garnered considerable attention in research. Nevertheless, prior studies on quartz in shale have concentrated on its influence on organic matter accumulation, pore development, and physical properties. The crystal morphology of quartz and its implications for shale reservoir performance have been largely overlooked. This study utilizes the Longmaxi (LMX) shale in the Sichuan Basin, China, as an example to conduct this work. We used X-ray powder diffraction, polarizing microscopy, scanning electron microscopy, and cathodoluminescence testing, characterizing the crystallinity and characteristics of quartz, revealing the influence of quartz crystallinity on shale reservoirs. The results indicate that the quartz crystallinity index (QCI) of the LMX shale ranges from 2.81 to 8.09, and a significant correlation between the QCI and the sources of quartz is observed. Shale samples with lower QCI values tend to exhibit a higher content of biogenic quartz, whereas the content of clay-transformed quartz and/or terrigenous detrital quartz increases. Furthermore, the pore structure parameters of shale exhibit synergistic variations with QCI, especially for shale with low crystallinity, despite showcasing differences for pores with different pore sizes. Notably, QCI exhibits the strongest negative correlation with micropores, followed by mesopores, while this correlation is less apparent in macropores. The influence of QCI on pore development is primarily ascribed to its synergistic interaction with organic matter enrichment and the constraints imposed on the development and preservation of organic-matter-hosted pores. Under the well-preserved geological conditions of the LMX shale reservoirs, a definite correlation exists between the QCI value and shale gas content/production. This correlation signifies that QCI could serve as a potential indicator for assessing shale reservoir quality, complementing conventional parameters, such as the contents of total organic carbon and quartz.

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Section: Resultsmentioning

confidence: 97%

Section: Characteristics and Control Factors Of Quartzmentioning

confidence: 99%

Section: Characteristics and Control Factors Of Quartzmentioning

confidence: 99%

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Quartz Crystallinity Characteristics and Their Effects on Shale Gas Reservoir Performance: A Case Study of the Deep Longmaxi Formation Shale in the Sichuan Basin, China

Feng,

Xiao,

Wang

et al. 2024

ACS Earth Space Chem.

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“…The Sichuan Basin is one of the main petroliferous basins in China, with an area of 18×10 4 km 2 , the resource potential of natural gas is approximately 21.7×10 12 m 3 (Wang et al, 2022c;Zhang et al, 2022;Zhang et al, 2023). Within the Sichuan Basin, three distinct shale petroleum systems can be identified, characterized by different sedimentary environments.…”

Section: Geological Settingmentioning

confidence: 99%

Pore system and methane adsorption capacity features of marine and marine-continental transitional shale in the Sichuan Basin, SW China

Wang,

Guo,

Dong

et al. 2023

Front. Earth Sci.

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Recently, significant achievements have been made in the gas exploration of marine Longmaxi shale in China. As exploration efforts have advanced, the exploration targets have gradually expanded to other sedimentary systems (marine-continental transitional and lacustrine). Compared with marine shale, shale in other sedimentary systems shows stronger heterogeneity, rendering previous exploration experiences of marine shale ineffective in guiding exploration efforts. Therefore, there is a pressing need for comparative studies to support future exploration practices. In this paper, the marine Longmaxi Formation and the marine-continental transitional Longtan Formation shales in the Lintanchang area of the southeastern of the Sichuan Basin are selected as the research objects. The study aims to compare the mineralogical characteristics, pore systems, and methane adsorption capacities of these two sets of shales, thereby revealing the differences in controlling factors that affect their physical properties and methane adsorption capacities. Our results show that the Longtan shale exhibits a higher clay mineral content, while the Longmaxi shale demonstrates significantly higher siliceous mineral content. Compare with Longmaxi shale, the Longtan shale exhibits a wider distribution range and higher average value of TOC content. The pore system in the Longmaxi shale is primarily dominated by organic matter-related pores, whereas the Longtan shale is characterized by clay mineral-related pores as the primary pore type. Given the variance in sedimentary environments, the controlling factors of physical properties differ significantly between the two sets of shales. In the case of the Longmaxi shale, TOC content is the most influential factor governing physical properties, while clay mineral content exerts the most significant influence on physical properties in the Longtan shale. Furthermore, TOC content emerges as the primary factor affecting methane adsorption capacity in both the Longmaxi and Longtan shales, despite the presence of significant variations in their pore systems. Nevertheless, the specific mechanisms through which TOC content impacts methane adsorption capacity exhibit variations between the two distinct shale types under investigation. The difference in sedimentary environment leads to various effects of mineral composition on methane adsorption capacity. Therefore, in the future research, the influences of different factors on methane adsorption capacity should be studied in combination with the sedimentary background.

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“…The paleosedimentary environment plays a crucial role in organic matter (OM) enrichment, mineral composition, and pore system features. Consequently, the reconstruction of paleosedimentary environments holds significant importance for comprehending the mechanisms governing shale oil accumulation and identifying promising exploration targets [10,[20][21][22]. In geological history, the Jurassic emerges as a paradigmatic greenhouse period characterized by warm and humid conditions.…”

Section: Introductionmentioning

confidence: 99%

Geological Features, Paleosedimentary Environment, and Organic Matter Accumulation Mechanisms of the Lacustrine Shale Oil System: A Case Study of the Jurassic Dongyuemiao Member in the Sichuan Basin

Wang,

Li,

Guo

et al. 2023

Processes

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Lacustrine shale has garnered significant attention due to its significant resource potential. The Jurassic shale in the Sichuan Basin is an important target for lacustrine shale exploration in China. However, previous studies have predominantly focused on the Da’anzhai member of the Ziliujing Formation, and little attention has been paid to the shale of other strata. This paper aims to address this gap by investigating the Jurassic Dongyuemiao member in the Sichuan Basin. The study systematically characterizes the geological properties of the Dongyuemiao shale system, reconstructs the paleosedimentary environment, identifies the key factors influencing organic matter (OM) enrichment and physical properties, and assesses its resource potential through comparative analysis. Our results show that the Dongyuemiao shale was deposited in an oxic and semi-humid sedimentary environment characterized by intense weathering conditions. The enrichment of OM in the shale is primarily controlled by redox conditions and salinity, with redox conditions playing the most crucial role in OM accumulation. In terms of pore system characterization, clay mineral-associated pores dominate the pore types in the Dongyuemiao shale, while two types of organic matter-associated pores are also widely observed. The development of framework grain-associated pores is limited and only present in certain siliceous and carbonate minerals. The shales of the Dongyuemiao member and the Da’anzhai member exhibit slight differences in TOC content. However, the kerogen in the Dongyuemiao member displays higher hydrocarbon generation potential, and the Dongyuemiao shale exhibits more favorable pore structure parameters. Overall, the Dongyuemiao shale does not exhibit any significant disadvantages compared to the Da’anzhai shale. Therefore, it deserves greater attention in future exploration endeavors. The research findings presented in this paper provide a solid theoretical foundation for expanding the exploration scope of lacustrine shale in the Sichuan Basin.

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Influence of the Late Ordovician‐Early Silurian Paleoenvironment and Related Geological Processes on the Organic Matter Accumulation and Carbon Isotope Excursion

Cited by 5 publications

References 176 publications

Quartz Crystallinity Characteristics and Their Effects on Shale Gas Reservoir Performance: A Case Study of the Deep Longmaxi Formation Shale in the Sichuan Basin, China

Quartz Crystallinity Characteristics and Their Effects on Shale Gas Reservoir Performance: A Case Study of the Deep Longmaxi Formation Shale in the Sichuan Basin, China

Pore system and methane adsorption capacity features of marine and marine-continental transitional shale in the Sichuan Basin, SW China

Geological Features, Paleosedimentary Environment, and Organic Matter Accumulation Mechanisms of the Lacustrine Shale Oil System: A Case Study of the Jurassic Dongyuemiao Member in the Sichuan Basin

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