Paleoweathering, hydrothermal activity and organic matter enrichment during the formation of earliest Cambrian black strata in the northwest Tarim Basin, China

He, Taohua; Lu, Shuangfang; Li, Wenhao; Sun, Dexin; Pan, Wenqing; Zhang, Baoshou; Tan, Zhaozhao; Ying, Junfeng

doi:10.1016/j.petrol.2020.106987

Cited by 42 publications

(16 citation statements)

References 54 publications

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“…In summary, the redox and paleoproductivity of seawater, which finally controlled the organic matter accumulation, depend on hydrothermal activity and sea level fluctuation. In addition, the phenomenon that the Niu-1 member with strong hydrothermal activity but low TOC content and Niu-2 member with weak hydrothermal event but high TOC content found in our paper is consistent with that reported in Tarim Basin by [74].…”

Section: Terrigenous Clasticsupporting

confidence: 92%

“…Therefore, hydrothermal events may be the main causes of dysoxic to anoxia depositional environments in the Niu-1 member. A large number of reducing gases (e.g., H 2 S, CH 4 , H 2 , and CO) released during hydrothermal activity can lead to a benthic anoxic condition [74,75]. In addition, Ba-rich hydrothermal fluid, accompanied by abundant nutrient elements, vented along the deep-seated faults in shelf and basinal regions, resulting in nutrientrich bottom waters.…”

Section: Terrigenous Clasticmentioning

confidence: 99%

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Constraints on the Organic Matter Accumulation of Lower Cambrian Niutitang Shales in the Middle Yangtze Region, South China

et al. 2021

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The lower Cambrian Niutitang shales, as one of target intervals with the greatest potential for shale gas exploration and development, have attracted much attention. Nevertheless, the organic matter enrichment mechanisms of the lower Cambrian Niutitang shales need further study, especially in the hydrothermal active zone. In this study, samples from ND1 well in western Hubei Province, middle Yangtze region, South China, were investigated for the controlling factors of organic matter accumulation of Lower Cambrian Niutitang shales by detailed petrographic, mineralogic, and geochemical proxies. The results show that hydrothermal activity and sea level fluctuation controlled the redox conditions and paleoproductivity of seawater and ultimately controlled the organic matter accumulation of Niutitang formation. In the Niu-1 member, the intense hydrothermal events lead to a suboxic to anoxic environment, which is conducive to the organic matter preservation. However, low sea level strengthens the restriction of water mass and reduced nutrient upwelling into the shelf, leading to decreased marine primary productivity, which was ultimately responsible for depleted organic matter accumulation in the Niu-1 member. In the Niu-2 member, the anoxic-euxinic environment and high paleoproductivity, driven by continuous hydrothermal activity and rising sea level, were the main factors controlling the enrichment of organic matter. In the Niu-3 member, the dysoxic to oxic condition plus low primary productivity, caused by the disappearance of hydrothermal activities and sea-level fall, resulted in the unfavorable organic matter accumulation. The results of this paper enrich the model of organic matter enrichment in the lower Cambrian black shale in the middle Yangtze region.

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Section: Terrigenous Clasticsupporting

confidence: 92%

Section: Terrigenous Clasticmentioning

confidence: 99%

Constraints on the Organic Matter Accumulation of Lower Cambrian Niutitang Shales in the Middle Yangtze Region, South China

et al. 2021

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“…It is generally believed that clay minerals have strong adsorptivity, and organic matter can adhere to it, so that organic matter can be deposited and buried quickly. Therefore, the existence of clay minerals is conducive to the formation of sedimentary organic matter. − However, the abundance of organic matter is also affected by sedimentary water bodies and paleo-productivity. A high clay content means more terrestrial input, weak paleo-productivity, and low organic matter abundance.…”

Section: Resultsmentioning

confidence: 99%

Analysis of Adsorption Characteristics and Influencing Factors of Wufeng–Longmaxi Formation Shale in Sichuan Basin

Kong¹,

Xiao

et al. 2021

Energy Fuels

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Shale gas resources provide a new impetus to alleviate the contradiction between China's oil and gas supply and demand. As an important part of shale gas, understanding the occurrence mechanism of adsorbed gas can help shale gas resources to be better developed and used. This time, a series of experiments, such as low-temperature nitrogen adsorption and methane isotherm adsorption, were conducted to discuss the pore structure, adsorption performance, and adsorption mechanism of shale. The results show the following: (1) Shale pores are dominated by nanopores, and pores with a pore width of less than 2 nm have the best relationship with the shale surface area and adsorption capacity. (2) Total organic carbon (TOC) plays an important role in controlling the specific surface area and methane adsorption capacity of shale. This is mainly due to the large number of micropores (pore size of <2 nm) developed in organic matter. Micropores provide the main specific surface area and adsorption sites for methane adsorption. (3) A variety of models were used to fit shale methane isotherm adsorption data. The results show that the SDR model and Langmuir model have the best fit. The methane adsorption performance of shale is controlled by many factors; the adsorption capacity becomes weaker as the temperature rises; and this influence is also affected by TOC. (4) In comparison to the adsorption capacity, the change of the adsorbed phase density is more complicated: overall, there is a weak positive correlation with TOC; as the temperature increases, the adsorbed phase density decreases. However, this law is not stable, and there are different performances in different experiments. (5) The adsorption comparison results show that the shale methane adsorption is mainly multilayer adsorption and micropore filling.

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“…There are several significant differences between marine shale and CFSR [24][25][26][27][28]. CFSR is strongly affected by the sediment source and sedimentary environments [29,30]. Consequently, CFSR is highly heterogeneous, which is primarily manifested in the mineral types, rock compositions, structural characteristics, pore space, organic matter (OM) characteristics, and hydrocarbon mobility [31][32][33][34][35][36].…”

Section: Introductionmentioning

confidence: 99%

Coupling Relationship between Lithofacies and Brittleness of the Shale Oil Reservoir: A Case Study of the Shahejie Formation in the Raoyang Sag

Song

et al. 2022

Geofluids

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Analyzing the characteristics of rock brittleness in low-permeability mudstone and shale (MS) formations is imperative for efficient hydraulic fracturing stimulation. Rock brittleness depends on the mineral composition, organic matter abundance, and bedding structure. Based on the MS from Shahejie Formation mineral composition (clay mineral, felsic mineral, and calcareous mineral contents), total organic content, and bedding structure (laminated, laminar, and massive), six types of lithofacies were identified: clay-rich MS, felsic-rich MS, calcareous-rich MS, clay MS, felsic MS, and calcareous MS. The quartz, feldspar, calcite, and dolomite of the Shahejie Formation are brittle minerals. Consequently, lithofacies with high felsic and calcareous mineral contents are more brittle. In addition, laminated and laminar MS are also conducive to hydraulic fracturing. Therefore, laminated, organic-rich, and calcareous-rich MS are the dominant lithofacies for hydraulic fracturing in the Shahejie Formation. The lithofacies and brittleness index were predicted by the response characteristics between mineral compositions and logging curves. The 3521–3552 m section of well B11x is dominated by calcareous-rich MS with developed laminae, representing a favorable section for hydraulic fracturing. Fragile minerals and oil are widely developed in the lower part of the lower 1st member of the Shahejie Formation (Es1L) in the southwestern part of Zhaohuangzhuang-Suning, where hydraulic fracturing can be used to increase shale oil production.

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Paleoweathering, hydrothermal activity and organic matter enrichment during the formation of earliest Cambrian black strata in the northwest Tarim Basin, China

Cited by 42 publications

References 54 publications

Constraints on the Organic Matter Accumulation of Lower Cambrian Niutitang Shales in the Middle Yangtze Region, South China

Constraints on the Organic Matter Accumulation of Lower Cambrian Niutitang Shales in the Middle Yangtze Region, South China

Analysis of Adsorption Characteristics and Influencing Factors of Wufeng–Longmaxi Formation Shale in Sichuan Basin

Coupling Relationship between Lithofacies and Brittleness of the Shale Oil Reservoir: A Case Study of the Shahejie Formation in the Raoyang Sag

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