ORIGINAL RESEARCH article
Front. Earth Sci.
Sec. Economic Geology
Volume 13 - 2025 | doi: 10.3389/feart.2025.1650521
This article is part of the Research TopicAdvances in Accumulation Conditions of Unconventional Oil and Gas Resources in Complicated Structure AreasView all 4 articles
Reservoir Heterogeneity in Deep Marine-Continental Transitional Shales: The Role of Lithofacies and Quality in the Coal-Bearing Longtan Formation,Central Sichuan Basin
Provisionally accepted
Longyi Wang1,2,3
Xizhe Li1,2,3*
Yana Chen2,4Hongming Zhan2*Xiangyang Pei2Yuchuan Chen5Nijin Qi1,2Weikang He1,2Wenxuan Yu2Yaoqiang Lin2Yuhang Zhou1,2- 1University of Chinese Academy of Sciences, Beijing, China
- 2Research Institute of Petroleum Exploration and Development, Beijing, China
- 3Institute of Porous Flow and Fluid Mechanics China National Petroleum Corporation and Chinese Academy of Sciences, Langfang, China
- 4PetroChina Hangzhou Institute of Petroleum Geology, Hangzhou, China
- 5China University of Geosciences Beijing, Beijing, China
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Compared with marine shale formations, marine-terrestrial transitional shales exhibit rapid lithofacies changes. This poses significant challenges for the classification of shale lithofacies and the study of their characteristics. The Permian Longtan Formation (LTF) coal-measure shale in marine-terrestrial transitional facies in the central-southern Sichuan Basin is expected to be a new gas-rich formation with development value in China.Based on core observation and thin-section identification, and using techniques such as XRD, TOC analysis, field-emission scanning electron microscopy, lowtemperature gas adsorption, and high-pressure mercury intrusion, this study systematically analyzed the lithofacies types, geochemical characteristics, and pore features of the LTF coal-measure shale in the deep area of the central Sichuan Basin.The study shows that the shale in the studied interval mainly developed four lithofacies: organic-rich clay shale (CS-H), medium-organic mixed shale (MS-M), medium-organic siliceous shale, and low-organic calcareous shale (CAS-L).The four lithofacies are interbedded with each other, and their characteristics differ significantly.Clay content and TOC content are the main factors affecting their quality.Through multiparameter analysis, it is determined that the CS-H lithofacies has a good hydrocarbon generation basis, well-developed pores, and good preservation conditions, making it a high-quality lithofacies.The research conclusions provide important insights into the study of marine-terrestrial transitional shale formations and offer a basis for further advancing the development and utilization of transitional shales.
Keywords: Marine-continental transitional facies, Longtan Formation, Shale lithofacies, Pore features, Lithofacies Quality
Received: 20 Jun 2025; Accepted: 24 Jul 2025.
Copyright: © 2025 Wang, Li, Chen, Zhan, Pei, Chen, Qi, He, Yu, Lin and Zhou. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Xizhe Li, University of Chinese Academy of Sciences, Beijing, China
Hongming Zhan, Research Institute of Petroleum Exploration and Development, Beijing, China
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