Sedimentary environment controls on the lacustrine shale lithofacies: A case study from the Nanpu depression, Bohai Bay Basin

Liu, Huan; Liu, Xiaoping; Liu, Guoyong; Li, Guoyong; Wang, Jianwei; Gao, Yongliang; Sun, Biao; Hou, J.; Liu, Hanxi; Sun, Xueliang

doi:10.1016/j.geoen.2023.211704

Cited by 3 publications

(4 citation statements)

References 56 publications

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“…0.26%). A significant positive correlation between the TiO2 and Al2O3 content in the Es3l to Es4u interval (Figure 10), with a correlation coefficient R2 = 0.955, indicates a close association with terrigenous input, supporting the effectiveness of these proxies in assessing terrigenous detrital influx [50,64]. The sharp rise and subsequent decline in the Ti content in the middle of Es4u, combined with other geochemical proxies, suggest a gradual overall increase in terrigenous detrital influx from the bottom to the top of Es3l-Es4u.…”

Section: Terrigenous Detrital Influxmentioning

confidence: 82%

“…Lithofacies with more than 2% organic matter are classified as organic-rich lithofacies, accounting for about 62.85% (Figure 5a); those with 1% to 2% organic matter are organic-moderate lithofacies, representing 34.29% (Figure 5a); and those with less than 1% organic matter are organic-poor lithofacies, the least common at 2.86% (Figure 5a). Regarding sedimentary structures, those with single-layer thicknesses less than 1 mm are classified as laminated, more than 1 mm as layered, and those with unclear bedding structures as massive [50]. In the study interval from Es3l to Es4u, developed laminated structures make up 80%, layered structures are extremely rare at 1.43%, and massive structures account for 18.57% (Figure 5b).…”

Section: Lithofacies Classification Scheme and Main Lithofacies Typesmentioning

confidence: 99%

“…This is believed to be associated with the continuous deepening of the lake body due to increased precipitation in a more humid climate, leading to an increase in terrigenous clastic influx and a reduction in early carbonate precipitation. This phenomenon can be understood using the concept of "Carbonate Compensation Depth (CCD)" from oceanography [50]. Carbonate precipitation depends on the relationship between the rate of carbonate production and dissolution, with the dissolution rate controlled by water depth.…”

Section: Depositional Stage IVmentioning

confidence: 99%

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Lithofacies Characteristics of Continental Lacustrine Fine-Grained Sedimentary Rocks and Their Coupling Relationship with Sedimentary Environments: Insights from the Shahejie Formation, Dongying Sag

Guo,

Shi,

et al. 2024

Minerals

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Lacustrine fine-grained sedimentary rocks in the Dongying Sag of the Bohai Bay Basin in China exhibit significant potential for hydrocarbon exploration. This study investigates the lithofacies types and sedimentary evolution of the Paleogene Shahejie Formation’s lower third member (Es3l) and upper fourth member (Es4u), integrating petrological and geochemical analyses to explore the relationship between lithofacies characteristics and sedimentary environments. The results show that the fine-grained sedimentary rocks in the study area can be classified into 18 lithofacies, with seven principal ones, including organic-rich laminated carbonate fine-grained mixed sedimentary rock lithofacies and organic-rich laminated limestone lithofacies. In conjunction with analyses of vertical changes in geochemical proxies such as paleoclimate (e.g., CIA, Na/Al), paleoproductivity (e.g., Ba), paleosalinity (e.g., Sr/Ba), paleo-redox conditions (e.g., V/Sc, V/V + Ni), and terrigenous detrital influx (e.g., Al, Ti), five stages are delineated from bottom to top. These stages demonstrate a general transition from an arid to humid paleoclimate, a steady increase in paleoproductivity, a gradual decrease in paleosalinity, an overall reducing water body environment, and an increasing trend of terrestrial detrital input. This study demonstrates that the abundance of organic matter is primarily influenced by paleoproductivity and paleo-redox conditions. The variations in rock components are predominantly influenced by paleoclimate, and sedimentary structures are affected by the depth of the lake basin. Special depositional events, such as storm events in Stage II, have significantly impacted the abundance of organic matter, rock components, and sedimentary structures by disturbing the water column and disrupting the reducing conditions at the lake bottom. The present study offers crucial insights into the genesis mechanisms of continental lacustrine fine-grained sedimentary rocks, facilitates the prediction of lithofacies distribution, and advances the exploration of China’s shale oil resources in lacustrine environments.

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Section: Terrigenous Detrital Influxmentioning

confidence: 82%

Section: Lithofacies Classification Scheme and Main Lithofacies Typesmentioning

confidence: 99%

Section: Depositional Stage IVmentioning

confidence: 99%

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Lithofacies Characteristics of Continental Lacustrine Fine-Grained Sedimentary Rocks and Their Coupling Relationship with Sedimentary Environments: Insights from the Shahejie Formation, Dongying Sag

Guo,

Shi,

et al. 2024

Minerals

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“…In this scenario, the reducing environment resulting from high salinity is the main driving force behind OM enrichment. , Consequently, the salinity and TOC content are positively correlated. Examples of such conditions can be found in the Shahejie Formation in Dongpu Sag, , Shahejie Formation in Nanpu Sag, and Lucaogou Formation in Santanghu Basin . Under hypersaline conditions, the paleoclimate is dry and hot, which is unfavorable for the influx of terrigenous higher plants, and high salinity causes the death of aquatic organisms.…”

Section: Discussionmentioning

confidence: 99%

Favorable Exploration Lithofacies and Their Formation Mechanisms in Lacustrine Shales Deposited under Different Salinity Conditions: Insights into Organic Matter Accumulation and Pore Systems

Wang

Guo

et al. 2023

Energy Fuels

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Efficient identification of favorable exploration lithofacies with commercial value is of utmost importance in lacustrine shale petroleum exploration. Shales deposited under different salinity conditions exhibit considerably different organic matter (OM) accumulation and mineral compositions. However, the systematic summarization of favorable exploration lithofacies and their formation mechanisms in lacustrine shale systems formed under different salinity conditions is still lacking. Herein, lacustrine shale of the Lower Jurassic Qianfoya Formation (J 1 q) from the Langzhong Area of the Sichuan Basin is studied to systematically reveal its OM accumulation mechanisms and the factors controlling its physical properties. By combining our data with that published in the literature, the favorable exploration lithofacies and their formation mechanisms in lacustrine shales deposited under various different salinities (i.e., freshwater, saline, and hypersaline) are discussed. Our findings indicate that the J 1 q shale comprises four lithofacies, namely, organic-lean mixed shale (LM), organic-lean argillaceous shale (LCM), organic-rich mixed shale (RM), and organic-rich argillaceous shale (RCM). The pore systems of RCM and RM are dominated by OM-related pores, whereas those of LCM and LM are dominated by clay mineral-related pores. The J 1 q shale was deposited in an oxic environment with a semiarid to semihumid climate, moderate weathering, and freshwater to brackish conditions. The OM content is primarily influenced by the relatively reductive environment. The physical properties of RCM and RM are primarily determined by the total organic carbon (TOC) content, whereas those of LCM and LM are determined by the clay mineral content. Additionally, a novel model for describing the change in the TOC content, pore system characteristics, and fracability of shale with an increase in salinity is proposed. The model shows that with an increase in salinity, the TOC content first decreases, then increases, and finally decreases. Simultaneously, there is an improvement in the proportion of framework-grain related pores within the pore system. RCM, RM, and tight sandstone and limestone interlayers within freshwater lacustrine shale can be regarded as primary sweet spots. In the saline and hypersaline lacustrine shale systems, the main exploration targets are RM and organic-rich calcareous shale. These observations provide theoretical guidance for locating sweet spots in lacustrine shale systems deposited under different salinity conditions.

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Control of complex lithofacies on the shale oil potential in saline lacustrine basins of the Jimsar Sag, NW China: Coupling mechanisms and conceptual models

He,

Luo,

Jiang

et al. 2024

Journal of Asian Earth Sciences

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Sedimentary environment controls on the lacustrine shale lithofacies: A case study from the Nanpu depression, Bohai Bay Basin

Cited by 3 publications

References 56 publications

Lithofacies Characteristics of Continental Lacustrine Fine-Grained Sedimentary Rocks and Their Coupling Relationship with Sedimentary Environments: Insights from the Shahejie Formation, Dongying Sag

Lithofacies Characteristics of Continental Lacustrine Fine-Grained Sedimentary Rocks and Their Coupling Relationship with Sedimentary Environments: Insights from the Shahejie Formation, Dongying Sag

Favorable Exploration Lithofacies and Their Formation Mechanisms in Lacustrine Shales Deposited under Different Salinity Conditions: Insights into Organic Matter Accumulation and Pore Systems

Control of complex lithofacies on the shale oil potential in saline lacustrine basins of the Jimsar Sag, NW China: Coupling mechanisms and conceptual models

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