Burial history and the evolution of hydrocarbon generation in Carboniferous-Permian coal measures within the Jiyang super-depression, China

Han Sijie,Liang Jingjing,Jia Jinlong,Zhou Peiming,Sang Shuxun

doi:10.15446/esrj.v24n4.63220

Han Sijie, Liang Jingjing + Show 3 more

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https://doi.org/10.15446/esrj.v24n4.63220

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Abstract

In the Jiyang Sub-basin, Carboniferous-Permian (C-P) coal-measure source rocks have experienced complex multi-stage tectonics and therefore have a complex history of hydrocarbon generation. Because these coal measures underwent multi-stage burial and exhumation, they are characterized by various burial depths. In this study, we used the basin modeling technique to analyze the relationship between burial history and hydrocarbon generation evolution. The burial, thermal and maturity histories of C-P coals were reconstructed, including primary hydrocarbon generation, stagnation, re-initiation, and peak secondary hydrocarbon generation. The secondary hydrocarbon generation stage within this reconstruction was characterized by discontinuous generation and geographical differences in maturity due to the coupled effects of depth and a delay of hydrocarbon generation. According to the maturity history and the delay effect on secondary hydrocarbon generation, we concluded that the threshold depth of secondary hydrocarbon generation in the Jiyang Sub-basin occurred at 2,100 m during the Yanshan epoch (from 205 Ma to 65 Ma) and at 3,200 m during the Himalayan period (from 65 Ma to present). Based on depth, residual thickness, maturity, and hydrocarbon-generating intensity, five favorable areas of secondary hydrocarbon generation in the Jiyang Sub-basin were identified, including the Chexi areas, Gubei-Luojia areas, Yangxin areas, the southern slope of the Huimin depression and southwest of the Dongying depression. The maximum VRo/burial depth (%/km) occurred in the Indosinian epoch as the maximum VRo/time (%/100Ma) happened in the Himalayan period, indicating that the coupling controls of temperature and subsidence rate on maturation evolution play a significant role in the hydrocarbon generation evolution. A higher temperature and subsidence rate can both enhance the hydrocarbon generation evolution.

Highlights

The Jiyang Sub-basin is a secondary structural unit in the Bohai Bay Basin, which contains rich oil and gas resources; it has significant potential for exploration and development (Pang et al, 2003; Li et al, 2006; Jin et al, 2009)
Recent studies investigating hydrocarbon accumulation in the Jiyang Sub-basin have focused on Palaeogene and Neogene sandmudstone reservoir systems and associated Cenozoic source rocks that include multilayer organic-rich argillaceous strata (Zhu et al, 2005, 2007; Zhang et al, 2016)
Owing to the presence of faults and surface unconformities, the formation of a petroleum system consisting of Cenozoic oil and gas reservoirs from Palaeozoic source rocks remains problematic unless structural conditions are favorable (Zhang et al, 2004, 2009b)

Summary

Introduction

The Jiyang Sub-basin is a secondary structural unit in the Bohai Bay Basin, which contains rich oil and gas resources; it has significant potential for exploration and development (Pang et al, 2003; Li et al, 2006; Jin et al, 2009). Burial history of Carboniferous-Permian coals and its impact on secondary hydrocarbon generation in the Jiyang Sub-basin, China. The aim of this study was to confirm secondary hydrocarbon generation occurred and establish a relationship between burial history and the evolution of source rock maturity in the Jiyang Sub-basin.

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Results

Conclusion