Abstract

The marine shale in southern China has undergone complex tectonic evolution with a high thermal evolution degree. Excessive thermal evolution brings certain risks to shale gas exploration and development. With the advancement of experimental methods, the evolution process of shale reservoirs can be better understood from the micro-nanoscale. This work takes the Ordovician-Silurian Wufeng and the first member of Longmaxi Formation in the Sichuan Basin and Lower Cambrian Niutitang Formation in Outer Margin of the Sichuan Basin to study the impact of maturity upon the genesis of shale gas and development features of the reservoir. A series of geochemical research methods, including TOC, gas component and gas isotope, were adopted to study the impact of different thermal evolution stages of organic matter upon the genesis of shale gas. The nanoscale micro-imaging technique, such as FIB-SEM and FIB-HIM, was used to analyze the development of OM-hosted pores. As shown from the results, when Ro = 1.2–3.5%, the marine shale gas is dominated by methane and other hydrocarbon gases, since the mixture of cracking gas from liquid hydrocarbons and kerogen-cracking gas cause the carbon isotope reversal. Besides, the pyrobitumen pores characterized by the strong connectivity and storage capacity were primarily developed. When Ro > 3.5%, the organic matter is at the graphitization stage. The shale gas is mainly composed of nitrogen at this stage. The nitrogen is originated from the atmosphere and the thermal evolution process, and the OM-hosted pores (pyrobitumen and kerogen pores) characterized by the bad connectivity and storage capacity are developed. Finally, the main component of shale gas, the genesis of shale gas and the pattern of OM-hosted pores under different thermal evolution stages of organic matter are summarized, which provide technical support for the exploration and development of shale gas.

Details

Title
Effect of organic maturity on shale gas genesis and pores development: A case study on marine shale in the upper Yangtze region, South China
Author
Zhang, Kun 1 ; Peng, Jun 2 ; Wang, Xin 3 ; Jiang, Zhenxue 3 ; Song, Yan 4 ; Jiang, Lin 5 ; Jiang, Shu 6 ; Xue, Zixin 3 ; Wen, Ming 3 ; Li, Xiaohui 3 ; Liu, Xiaoxue 3 ; Huang, Yizhou 7 ; Wang, Pengfei 8 ; Chang’an Shan 9 ; Liu, Tianlin 10 ; Xie, Xuelian 11 

 School of Geoscience and Technology, Southwest Petroleum University, Chengdu, 610500, China; State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China; Key Laboratory of Tectonics and Petroleum Resources (China University of Geosciences), Ministry of Education, Wuhan 430074, China 
 School of Geoscience and Technology, Southwest Petroleum University, Chengdu, 610500, China 
 State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China; Unconventional Natural Gas Institute, China University of Petroleum, Beijing 102249, China 
 State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China; Unconventional Natural Gas Institute, China University of Petroleum, Beijing 102249, China; Research Institute of Petroleum Exploration and Development, Beijing 100083, China 
 Research Institute of Petroleum Exploration and Development, Beijing 100083, China 
 Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China; Research Institute of Unconventional Oil & Gas and Renewable Energy, China University of Petroleum (East China), Qingdao 266580, China; Energy and Geoscience Institute, University of Utah, Salt Lake City, Utah 84108, United States of America 
 Organic Geochemistry Unit, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, UK 
 Geoscience Documentation Center, China Geological Survey, Beijing 100083, China 
 School of Earth Sciences and Engineering, Xi’an Shiyou University, Xi’an 710065, China 
10  State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China 
11  Guangzhou Marine Geological survey, Guangzhou 510760, China 
Pages
1617-1629
Publication year
2020
Publication date
2020
Publisher
De Gruyter Poland
e-ISSN
23915447
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2732546546
Copyright
© 2020. This work is published under http://creativecommons.org/licenses/by/4.0 (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.