scholarly journals Paleovegetational Reconstruction and Implications on Formation of Oil Shale and Coal in the Lower Cretaceous Laoheishan Basin (NE China): Evidence from Palynology and Terpenoid Biomarkers

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4704
Author(s):  
Yu Song ◽  
Kai Zhu ◽  
Yinbo Xu ◽  
Qingtao Meng ◽  
Zhaojun Liu ◽  
...  

In some cases, the oil shale deposited in shallow lakes may be genetically associated with the coal-bearing successions. Although paleovegetation is an important controlling factor for the formation of oil shale- and coal-bearing successions, few studies have focused on their joint characterization. In this study, a total of twenty-one oil shale and coal samples were collected from the upper member of the Lower Cretaceous Muling Formation (K1ml2) in the Laoheishan Basin, and investigated for their bulk geochemical, maceral, palynological, and terpenoid biomarker characteristics, in order to reconstruct the paleovegetation and reveal its influence on the formation of oil shale and coal. The K1ml2 is subdivided into lower, middle, and upper units. The studied oil shale samples from the lower and upper units display a high ash yield (Ad), low total organic carbon (TOC) and sulfur (S) contents, and limited hydrocarbon generation potential. The studied coal samples from the middle unit are characterized by low Ad, and high TOC and low S values, and show significant hydrocarbon generation potential. The paleovegetation during the formation of the lower unit was dominated by mire vegetation, such as shrubs (e.g., Lygodiaceae, Schizaeaceae), tree ferns (e.g., Dicksoniaceae/Cyatheaceae), and coniferous trees (e.g., Podocarpaceae). In the middle unit interval, the paleovegetation was represented by highland vegetation (Pinaceae and Araucariaceae) and peat-forming coniferous plants (e.g., Podocarpaceae, Cupressaceae/Taxodiaceae). Various vegetation, such as herbs (e.g., Osmundaceae), shrubs (e.g., Schizaeaceae), and coniferous trees (e.g., Podocarpaceae) was prosperous during the upper unit interval. Coniferous trees could provide abundant hydrogen-rich materials (e.g., resins) to the mire/lake, which may elevate the hydrogen content in peat/lake sediments, and finally result in higher hydrocarbon generation potential in the coal than in the oil shale. Therefore, the influence of paleovegetation on the formation of oil shale and coal should be fully considered when studying oil shale- and coal-bearing successions. The results also provide guidance for further exploration studies on oil shale and coal in northeast China.

2018 ◽  
Vol 33 (1) ◽  
pp. 89-105 ◽  
Author(s):  
Yousif M. Makeen ◽  
Wan Hasiah Abdullah ◽  
Muhammad Nadzmi Abdul Ghofur ◽  
Habeeb A. Ayinla ◽  
Mohammed Hail Hakimi ◽  
...  

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1043
Author(s):  
Jinliang Zhang ◽  
Jiaqi Guo ◽  
Yang Li ◽  
Zhongqiang Sun

The Changling Depression is the largest and most resource-abundant reservoir in the South Songliao Basin, NE China. The petroleum evolution rules in the Lower Cretaceous deep tight sandstone reservoir are unclear. In this study, 3D basin modeling is performed to analyze the large-scale petroleum stereoscopic migration and accumulation history. The Changling Depression has a complex fault system and multiple tectonic movements. The model is calibrated by the present formation temperatures and observed maturity (vitrinite reflectance). We consider (1) three main erosion episodes during the burial history, one during the Early Cretaceous and two during the Late Cretaceous; (2) the regional heat flow distribution throughout geological history, which was calibrated by abundant measurement data; and (3) a tight sandstone porosity model, which is calibrated by experimental petrophysical parameters. The maturity levels of the Lower Cretaceous source rocks are reconstructed and showed good gas-generation potential. The highest maturity regions are in the southwestern sag and northern sag. The peak hydrocarbon generation period contributed little to the reservoir because of a lack of seal rocks. Homogenization temperature analysis of inclusions indicated two sets of critical moments of gas accumulation. The hydrocarbon filling in the Haerjin and Shuangtuozi structures occurred between 80 Ma and 66 Ma, while the Dalaoyefu and Fulongquan structures experienced long-term hydrocarbon accumulation from 100 Ma to 67 Ma. The homogenization temperatures of the fluid inclusions may indicate a certain stage of reservoir formation and, in combination with the hydrocarbon-accumulation simulation, can distinguish leakage and recharging events.


Fuel ◽  
2021 ◽  
Vol 291 ◽  
pp. 120205
Author(s):  
shucheng Liu ◽  
Hongyu Zhao ◽  
Tao Fan ◽  
Jun Zhou ◽  
Xiangyang Liu ◽  
...  

Oil Shale ◽  
2018 ◽  
Vol 35 (4) ◽  
pp. 304
Author(s):  
F HU ◽  
Z LIU ◽  
Q MENG ◽  
J WANG ◽  
Q SONG ◽  
...  

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