scholarly journals Hydrocarbon Generation Potential and Depositional Setting of Eocene Oil-Prone Coaly Source Rocks in the Xihu Sag, East China Sea Shelf Basin

ACS Omega ◽  
2020 ◽  
Vol 5 (50) ◽  
pp. 32267-32285
Author(s):  
Shilong Kang ◽  
Longyi Shao ◽  
Lanzhi Qin ◽  
Shuxia Li ◽  
Jinshui Liu ◽  
...  
Keyword(s):  
East China Sea ◽  
Source Rocks ◽  
East China ◽  
Hydrocarbon Generation ◽  
China Sea ◽  
Hydrocarbon Generation Potential ◽  
East China Sea Shelf ◽  
Depositional Setting

scholarly journals Petrology and hydrocarbon significance of the coaly source rocks from the Pinghu Formation in the Xihu Sag, East China Sea Shelf Basin

2020 ◽  
Vol 38 (5) ◽  
pp. 1295-1319
Author(s):  
Jinshui Liu ◽  
Shilong Kang ◽  
Wenchao Shen ◽  
Lanzhi Qin ◽  
Qianyu Zhou ◽  
...  
Keyword(s):  
East China Sea ◽  
Oil And Gas ◽  
Liquid Hydrocarbon ◽  
Source Rocks ◽  
East China ◽  
Lower Amount ◽  
Hydrocarbon Generation ◽  
Total Hydrocarbon ◽  
China Sea ◽  
East China Sea Shelf

The Xihu Sag in the East China Sea Shelf Basin contains abundant oil and gas reserves and is a focus for hydrocarbon exploration and development. Source rocks are mainly coals and coal-measures mudstones in the Paleogene Pinghu and Huagang formations. Samples from the Pinghu Formation in the Xihu Sag were collected for petrology, total organic carbon, and Rock-Eval analysis for the purpose of investigating macerals component and their contributions to hydrocarbon generation potential. The coaly source rocks from the Pinghu Formation are dominated by vitrinite (average 86.18%) but have an obviously elevated content of liptinite (average 12.59%) and a much lower amount of inertinite (average 1.23%). Liptinite of the samples is mainly composed of resinite, with a small amount of cutinite, sporinite and alginate in descending order. TOC values are 37.55%–65.58% (average 49.16%). Effective HI values are 167–281 mg HC/g TOC (average 223.5 mg HC/g TOC), suggesting the organic matter is type II kerogen. Relatively high HI values and macerals components suggest that the coaly source rocks can generate both oil and gas. Although the liptinite in the coaly source rocks has a content lower than vitrinite values, it makes a significant contribution to both total hydrocarbon and liquid hydrocarbon generation. The contributions of vitrinite, liptinite and inertinite to the total hydrocarbon generation approximately are 63.21%, 36.46% and 0.33%, respectively. The contributions of vitrinite and liptinite to the liquid hydrocarbon generation are approximately 40.95% and 59.05%, respectively. These results demonstrate that the coaly source rocks are dominated by vitrinite macerals with a relatively higher content of liptinite macerals, especially resinite, and these source rocks are more prone to both total hydrocarbon and liquid hydrocarbon generation. Paleogene coaly source rocks from other parts of the world should be considered for their oil-prone nature.

scholarly journals Geochemical Characterization of the Eocene Coal-Bearing Source Rocks, Xihu Sag, East China Sea Shelf Basin, China: Implications for Origin and Depositional Environment of Organic Matter and Hydrocarbon Potential

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 909
Author(s):  
Xiong Cheng ◽  
Dujie Hou ◽  
Xinhuai Zhou ◽  
Jinshui Liu ◽  
Hui Diao ◽  
...  
Keyword(s):  
Organic Matter ◽  
East China Sea ◽  
Water Table ◽  
Depositional Environment ◽  
Source Rocks ◽  
East China ◽  
Gas Chromatography Mass Spectrometry ◽  
Peak Oil ◽  
China Sea ◽  
East China Sea Shelf

Eocene coal-bearing source rocks of the Pinghu Formation from the W-3 well in the western margin of the Xihu Sag, East China Sea Shelf Basin were analyzed using Rock-Eval pyrolysis and gas chromatography–mass spectrometry to investigate the samples’ source of organic matter, depositional environment, thermal maturity, and hydrocarbon generative potential. The distribution patterns of n-alkanes, isoprenoids and steranes, high Pr/Ph ratios, abundant diterpanes, and the presence of non-hopanoid triterpanes indicate predominant source input from higher land plants. The contribution of aquatic organic matter was occasionally slightly elevated probably due to a raised water table. High hopane/sterane ratios and the occurrence of bicyclic sesquiterpanes and A-ring degraded triterpanes suggest microbial activity and the input of microbial organisms. Overwhelming predominance of gymnosperm-derived diterpanes over angiosperm-derived triterpanes suggest a domination of gymnosperms over angiosperms in local palaeovegetation during the period of deposition. The high Pr/Ph ratios, the plot of Pr/n-C17 versus Ph/n-C18, the almost complete absence of gammacerane, and the distribution pattern of hopanes suggest that the samples were deposited in a relatively oxic environment. Generally, fluctuation of redox potential is coupled with source input, i.e., less oxic conditions were associated with more aquatic organic matter, suggesting an occasionally raised water table. Comprehensive maturity evaluation based on Ro, Tmax, and biomarker parameters shows that the samples constitute a natural maturation profile ranging from marginally mature to a near peak oil window. Hydrogen index and atomic H/C and O/C ratios of kerogens suggest that the samples mainly contain type II/III organic matter and could generate mixed oil and gas.

Simulation of hydrocarbon generation and expulsion for the dark mudstone with Type-Ⅲ kerogen in the Pinghu Formation of Xihu Sag in East China Sea Shelf Basin

2021 ◽  
Author(s):  
Chenjie Xu
Keyword(s):  
East China Sea ◽  
Source Rock ◽  
Open System ◽  
Oil And Gas ◽  
East China ◽  
Hydrocarbon Generation ◽  
Gas Generation ◽  
China Sea ◽  
East China Sea Shelf ◽  
Oil And Gas Resources

<p>In order to finely describe the hydrocarbon generation and expulsion process of source rocks and provide reasonable key parameters for quantitative evaluation of oil and gas resources, we carried out a simulation research under semi-open system on hydrocarbon generation and expulsion for the dark mudstone with Type-Ⅲ kerogen in the Eocene Pinghu Formation in the Xihu Sag, East China Sea Shelf Basin. The results show that the process of hydrocarbon generation and expulsion can be divided into five stages as follows:</p><ul><li><em>R</em><sub>o</sub> = 0.5%~0.7%, oil was generated slowly without expulsion;</li> <li><em>R</em><sub>o</sub> = 0.7%~1.0%, oil was generated and expelled rapidly;</li> <li><em>R</em><sub>o</sub> = 1.0%~1.5%, oil began to be cracked into hydrocarbon gas;</li> <li><em>R</em><sub>o</sub> = 1.5%~2.3%, gas generation predominated;</li> <li><em>R</em><sub>o </sub>> 2.3%, only dry gas was generated.</li> </ul><p>Oil expulsion threshold (<em>R</em><sub>o</sub>) of the source rock of this type is about 0.7% (<em>R</em><sub>o</sub> = 0.7%), having a wide gas-window of <em>R</em><sub>o</sub> = 1.0%~3.0%. So it can maintain relatively strong gas generation ability at high- and over-mature stages, belonging to gas-prone source rock. Following the study on experimental results and the characteristics of hydrocarbon generation and expulsion in samples, we established a set of mathematical models for the evaluation of the process and potential of gas generation and oil generation and expulsion of the dark mudstone with Type-Ⅲ kerogen in the study area. Compared with the thermal simulation experiment in a closed system, the cumulative yield of oil in the semi-open system is higher and closer to that under actual geological conditions. Accordingly, we may conclude that more oil and gas resources may exist in the Xihu Sag.</p>

Astronomical forcing of the Paleogene coal-bearing hydrocarbon source rocks of the East China Sea Shelf Basin

2020 ◽  
Vol 406 ◽  
pp. 105715 ◽  
Author(s):  
Jingyu Zhang ◽  
Damien Pas ◽  
Wout Krijgsman ◽  
Wei Wei ◽  
Xuebin Du ◽  
...  
Keyword(s):  
East China Sea ◽  
Source Rocks ◽  
East China ◽  
The East China Sea ◽  
China Sea ◽  
Hydrocarbon Source Rocks ◽  
East China Sea Shelf ◽  
Astronomical Forcing
Sign in / Sign up

Export Citation Format

Share Document