Controls on organic matter enrichment in source rocks of the Shahejie Formation in the southwestern Bozhong Sag, Bohai Bay Basin, China

2020 ◽  
Vol 560 ◽  
pp. 110026
Author(s):  
Jie Yin ◽  
Changgui Xu ◽  
Fang Hao ◽  
Qi Wang ◽  
Quanyun Miao ◽  
...  
Keyword(s):  
Organic Matter ◽  
Source Rocks ◽  
Bohai Bay ◽  
Bohai Bay Basin ◽  
Shahejie Formation

scholarly journals The influences of sedimentary environments on organic matter enrichment in fine-grained rocks of the Paleogene Shahejie formation in Nanpu Sag, Huanghua Depression, Bohai Bay Basin

2021 ◽  
pp. 014459872110310
Author(s):  
Min Li ◽  
Xiongqi Pang ◽  
Guoyong Liu ◽  
Di Chen ◽  
Lingjian Meng ◽  
...  
Keyword(s):  
Organic Matter ◽  
Source Rocks ◽  
Bohai Bay ◽  
Bohai Bay Basin ◽  
Humid Climate ◽  
High Productivity ◽  
Fine Grained ◽  
Huanghua Depression ◽  
Shahejie Formation ◽  
Nanpu Sag

The fine-grained rocks in the Paleogene Shahejie Formation in Nanpu Sag, Huanghua Depression, Bohai Bay Basin, are extremely important source rocks. These Paleogene rocks are mainly subdivided into organic-rich black shale and gray mudstone. The average total organic carbon contents of the shale and mudstone are 11.5 wt.% and 8.4 wt.%, respectively. The average hydrocarbon (HC)-generating potentials (which is equal to the sum of free hydrocarbons (S1) and potential hydrocarbons (S2)) of the shale and mudstone are 39.3 mg HC/g rock and 28.5 mg HC/g rock, respectively, with mean vitrinite reflectance values of 0.82% and 0.81%, respectively. The higher abundance of organic matter in the shale than in the mudstone is due mainly to paleoenvironmental differences. The chemical index of alteration values and Na/Al ratios reveal a warm and humid climate during shale deposition and a cold and dry climate during mudstone deposition. The biologically derived Ba and Ba/Al ratios indicate high productivity in both the shale and mudstone, with relatively low productivity in the shale. The shale formed in fresh to brackish water, whereas the mudstone was deposited in fresh water, with the former having a higher salinity. Compared with the shale, the mudstone underwent higher detrital input, exhibiting higher Si/Al and Ti/Al ratios. Shale deposition was more dysoxic than mudstone deposition. The organic matter enrichment of the shale sediments was controlled mainly by reducing conditions followed by moderate-to-high productivity, which was promoted by a warm and humid climate and salinity stratification. The organic matter enrichment of the mudstone was less than that of the shale and was controlled by relatively oxic conditions.

Hydrocarbon generation and evolution of the source rocks of the lower Es3 and upper Es4 members of the Shahejie Formation in the Niuzhuang Sub-sag, Jiyang Depression, Bohai Bay Basin, eastern China

2018 ◽  
Vol 6 (4) ◽  
pp. SN11-SN21
Author(s):  
Zhenkai Huang ◽  
Maowen Li ◽  
Quanyou Liu ◽  
Xiaomin Xie ◽  
Peng Liu ◽  
...  
Keyword(s):  
Activation Energy ◽  
Eastern China ◽  
Source Rocks ◽  
Bohai Bay ◽  
Hydrocarbon Generation ◽  
Bohai Bay Basin ◽  
Jiyang Depression ◽  
Generation Threshold ◽  
Oil Generation ◽  
Shahejie Formation

Systematic organic petrology and geochemistry analyses have been conducted in the source rocks of the lower Es3 and upper Es4 members of the Shahejie Formation in the Niuzhuang Sub-sag, Jiyang Depression, Bohai Bay Basin, eastern China. The results indicate that the main organic types of shale and nongypsum mudstone in the lower Es3 and upper Es4 member are I-II1 kerogen, and the predominant ([Formula: see text]) activation energy frequencies range from 57 to [Formula: see text]. The similar distribution characteristics in the two source rocks indicate that they have a similar hydrocarbon maturation process. An extensive pyrolysis analysis indicates that the source rocks of the upper Es4 member do not have an obvious double peak hydrocarbon generation model. Previous studies indicate that the hydrocarbon index peak at a depth of 2500–2700 m is affected by migrating hydrocarbon. Major differences are not observed in the hydrocarbon generation and evolution process of the shale and nongypsum mudstone. The primary oil generation threshold of the lower Es3 and upper Es4 members is approximately 3200 m, and the oil generation peak is approximately 3500 m. The activation energy distribution of the gypsum mudstone of the upper Es4 member is wider than that of the shale and nongypsum mudstone, and lower activation energies account for a larger proportion of the activation energies. The above factors may lead to a shallower oil generation threshold for gypsum mudstone compared with that for shale and nongypsum mudstone.

Application of biomarkers to petroleum migration in the Linyi fault area, Huimin Depression, Bohai Bay Basin, China

2017 ◽  
Vol 54 (3) ◽  
pp. 311-321
Author(s):  
Lixin Pei ◽  
Wenzhe Gang ◽  
Daming Wang ◽  
Min Xiong
Keyword(s):  
Hanging Wall ◽  
Source Rocks ◽  
Bohai Bay ◽  
Bohai Bay Basin ◽  
Petroleum Migration ◽  
Migration Direction ◽  
High Maturity ◽  
Shahejie Formation ◽  
Geochemical Investigation ◽  
Huimin Depression

A geochemical investigation was carried out on 32 crude oil samples to investigate the origin of the oil and to trace the migration direction in the Linyi fault area, Huimin Depression, Bohai Bay Basin, China. The oils, which were characterized by low gammacerane content and a dominance of C27 over C29 regular steranes, originated from the source rock of the third member of the Shahejie Formation (Es3) in the Linnan Sag. A sequential charge of low- and high-maturity oils from the Es3 source rocks resulted in a decrease in oil maturity in the migration direction. The petroleum migration direction in the footwall of the Linyi fault was northward, away from the fault, and the migration direction at the southwest end (in the hanging wall) of the Linyi fault was westward, along the fault, as evidenced by lateral gradients of biomarker parameters of various maturity, density, and viscosity.

Paleosalinity and Its Association with Organic Matter: A Case Study from the Eocene Shahejie Formation, Laizhou Bay Sag, Bohai Bay Basin (China)

2021 ◽  
Vol 20 (4) ◽  
pp. 741-754
Author(s):  
Haoran Liang ◽  
Guosheng Xu ◽  
Qing Yu ◽  
Fanghao Xu ◽  
Deying Wang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Laizhou Bay ◽  
Bohai Bay ◽  
Bohai Bay Basin ◽  
Shahejie Formation

scholarly journals Characteristics of nanopores in terrestrial low-maturity shale based on organic-inorganic interactions: A case study on the Shahejie Formation shale in the southern Bohai Bay Basin, Eastern China

2020 ◽  
Vol 600 (1) ◽  
pp. 012007
Author(s):  
Fu Deliang ◽  
Sun Lina ◽  
Xu Guosheng ◽  
Liang Haoran ◽  
Zhang Chen ◽  
...  
Keyword(s):  
Organic Matter ◽  
Surface Area ◽  
Pore Diameter ◽  
Eastern China ◽  
Bet Surface Area ◽  
Bohai Bay ◽  
Bohai Bay Basin ◽  
Pore Characteristics ◽  
Inorganic Matter ◽  
Shahejie Formation

Abstract In this study, the influence of organic matter and inorganic matter on the pore structure of the Shahejie Formation (E2-3S) shale in the Bohai Bay Basin, was analysed. The pore characteristics, including the BET surface area, BJH adsorption cumulative volume and average pore diameter of the original samples, extracted samples, H2O2-treated samples and kerogen samples, were analysed with low-pressure N2 adsorption experiment. The study showed that the soluble organic matter in low-maturity shale blocked a certain number of pores, which mainly had pore sizes below 5 nm. The solid organic matter mainly formed pore diameters of 1-2 nm and pore diameters larger than 10 nm. A large amount inorganic pore diameter in the ranges of less than 0.8 nm, 1-2 nm, and 2.3-20 nm was blocked by solid organic matter. The micropores formed by minerals were much more abundant than those formed by organic matter in the terrestrial low-maturity shale. The symbiotic relationship between the minerals and the organic matter led to a decrease in the specific surface area and pore volume of the terrestrial low-maturity shale.

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