Anatomy of a lacustrine stratigraphic sequence within the fourth member of the Eocene Shahejie Formation along the steep margin of the Dongying depression, eastern China

AAPG Bulletin ◽  
2019 ◽  
Vol 103 (2) ◽  
pp. 469-504
Author(s):  
Zhixin Li ◽  
Wan Yang ◽  
Yongshi Wang ◽  
Liqiang Zhang ◽  
Hongmei Luo ◽  
...  
Keyword(s):  
Eastern China ◽  
Stratigraphic Sequence ◽  
Dongying Depression ◽  
Shahejie Formation ◽  
Fourth Member

The Characteristics of Palaeogeomorphology in Ek1 and the Lower Part of Es4 of the Paleogene in Dongying Depression and its Significance to Petroleum Geology

2012 ◽  
Vol 524-527 ◽  
pp. 226-230
Author(s):  
Li An Liu ◽  
Jian Bo Han
Keyword(s):  
Petroleum Geology ◽  
Alluvial Fans ◽  
The South ◽  
Research Results ◽  
Northern Basin ◽  
Dongying Depression ◽  
Contour Graph ◽  
Shahejie Formation ◽  
Fourth Member

By using the data of drilling and logging and other materials, the contour graph of the thickness of the remnant strata can be worked out. After the compaction restoration of the graph, the original sedimentary thickness of the First Member of Kongdian Formation(Ek1) and the Lower Part of the Fourth Member of Shahejie Formation ( lower Es4) can be obtained and their palaeogeomorphology can be reconstructed. The research results show that palaeogeomorphology has an obvious control on the sedimentary systems of Ek1 and lower Es4. In the areas with higher mountains and steeper slopes in the northern basin, there mainly develop nearshore subaqueous fans while in the south of the basin, there mostly develop alluvial fans.

scholarly journals A Novel Redox Indicator based on Relative Abundances of C31 And C32 Homohopanes in the Eocene Lacustrine Dongying Depression, East China

2021 ◽  
Author(s):  
Chong Jiang ◽  
Haiping Huang ◽  
Zheng Li ◽  
Hong Zhang ◽  
Zheng Zhai
Keyword(s):  
Vitrinite Reflectance ◽  
Source Rocks ◽  
East China ◽  
Peak Oil ◽  
Dongying Depression ◽  
Anoxic Environments ◽  
Oil Generation ◽  
Shahejie Formation ◽  
The Impact ◽  
Fourth Member

Abstract A suite of oils and bitumens from the Eocene Shahejie Formation (Es) in the Dongying Depression, East China was geochemically characterized to illustrate the impact of source input and redox conditions on the distributions of pentacyclic terpanes. The fourth member (Es4) developed under highly reducing, sulfidic hypersaline conditions, while the third member (Es3) formed under dysoxic, brackish to freshwater conditions. Oils derived from Es4 are enriched in C32 homohopanes (C32H), while those from Es3 are prominently enriched in C31 homohopanes (C31H). The C32H/C31H ratio shows positive correlation with homohopane index (HHI), gammacerane index (G/C30H), and negative correlation with pristane/phytane (Pr/Ph) ratio, and can be used to evaluate oxic/anoxic conditions during deposition and diagenesis. High C32H/C31H ratio (> 0.8) is an important characteristic of oils derived from sulfidic, hypersaline anoxic environments, while low values (< 0.8) indicate non-sulfidic, dysoxic conditions. Extremely low C32H/C31H ratios (< 0.4) indicate strong oxic conditions of coal depsoition. Advantages to use C32H/C31H ratio as redox condition proxy compared to the HHI and gammacerane indexes are wider valid maturity range, less sensitive to biodegradation influence and better differentiation of reducing from oxic environments. Preferential cracking of C35-homohopanes leads HHI to be valid in a narrow maturity range before peak oil generation. No C35 homohopane can be reliably detected in the Es4 bitumens when vitrinite reflectance is > 0.75%, which explains the rare occurrence of high HHI values in Es4 source rocks. Gammacerane is thermally more stable and biologically more refractory than C30 hopane, leading G/C30H ratio more sensitive to maturation and biodegradation than C32H/C31H ratio. Meanwhile, both HHI and gammacerane index cannot differentiate level of oxidation. The C32H/C31H ratio can be applied globally as a novel redox proxy in addition to the Dongying Depression.

The Geochemical Characteristics of Constant Elements of Red Mudstones in the Lower Part of the Fourth Member of Shahejie Formation in Dongying Depression

2013 ◽  
Vol 772 ◽  
pp. 765-770
Author(s):  
Li’an Liu ◽  
Nian Hong Zhu
Keyword(s):  
Statistical Analysis ◽  
Source Area ◽  
Geochemical Characteristics ◽  
The Other ◽  
Single Source ◽  
Sedimentary Structures ◽  
Dongying Depression ◽  
Shahejie Formation ◽  
Fourth Member

The statistical analysis of constant elements of red mudstones in the lower part of the fourth member of Shahejie Formation (S4) in Dongying Depression shows that the red mudstones in the lower S4 of Dongying Depression can be classified into three major types based on the characteristics of their constant elements, which is closely relevant to the sedimentary structures of red mudstones. Among the three types of red mudstones, two types originate from one single source area while the other type embraces the characteristics of multi-sources.

scholarly journals Chemical compaction of deep buried mudstone and its influence on pressure prediction

2020 ◽  
Vol 600 (1) ◽  
pp. 012012
Author(s):  
Li Chao ◽  
Luo Xiaorong ◽  
Zhang Likuan ◽  
Lei Yuhong ◽  
Chen Ming ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Clay Minerals ◽  
Eastern China ◽  
Bohai Bay ◽  
Dongying Depression ◽  
Pore Pressure Prediction ◽  
Shahejie Formation ◽  
Vertical Effective Stress ◽  
The Impact ◽  
Transformation Of Clay Minerals

Abstract The chemical compaction of mudstones which is dominated by the transformation of clay minerals leads to significant changes in the mineral composition and microstructure of mudstone during process of deep burial. In particular, the transformation of smectite to illite in mudstones results in noticeable impact on the pore pressure formation and the overpressure logging responses. At present, the study about the pressurization mechanism of chemical compaction and the impact on overpressure logging responses is really weak, which made it hard to pore pressure identification and pressure prediction for deep buried formations. Taking the Paleogene Shahejie Formation in the Dongying depression of the Bohai Bay Basin in eastern China as typical case, this paper analyses the characteristics of clay mineral transformation of the Shahejie Formation in the Dongying depression, the logging responses of overpressures, and the influence of chemical compaction on the prediction of pore pressure. The results showed that the chemical compaction of mudstones changes the relationship between the petrophysical properties of mudstone and vertical effective stress and the logging responses of overpressure. The typical characteristic of chemical compaction manifested as density increase continuous with the depth. The normal compaction trends of the different compaction stages are the basis for overpressure mechanisms identification and pore pressure prediction. The depth of the rapid transformation of clay minerals has a good consistency with the top of overpressure zone (2000–2800 m) in Dongying depression, which indicates that the overpressure and its logging responses may be related to the chemical compaction of mudstones. The measured pressure in intervals deeper than 3000 m is closer to the predicted pressure based on the normal compaction trend of chemical compaction.

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