Oil & Gas Geology ›› 2025, Vol. 46 ›› Issue (1): 192-210.doi: 10.11743/ogg20250114

• Petroleum Geology • Previous Articles     Next Articles

Platform-trough differential evolution and recent findings on conventional and unconventional natural gas play fairways in the Middle Permian Maokou Formation, eastern Sichuan Basin

Jie GUO1,2,3(), Di XIAO1,2,3(), Bing LUO4, Benjian ZHANG4, Xiao CHEN4, Xihua ZHANG4, Minglong LI1,2,3, Xiucheng TAN1,2,3   

  1. 1.State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,Sichuan 610500,China
    2.Research Branch of State Energy Key Laboratory of Carbonate Oil and Gas,,Southwest Petroleum University,Chengdu,Sichuan 610500,China
    3.Sichuan Provincial Key Laboratory of Natural Gas Geology,Southwest Petroleum University,Chengdu,Sichuan 610500,China
    4.Research Institute of Exploration and Development,Southwest Oil & Gasfield Company,PetroChina,Chengdu,Sichuan 610051,China
  • Received:2024-09-04 Revised:2025-01-07 Online:2025-02-28 Published:2025-03-03
  • Contact: Di XIAO E-mail:19938294146@163.com;super_xd_mm@126.com

Abstract:

The unclear understanding of the Permian rifting evolution and sedimentary filling patterns in the Sichuan Basin has hindered hydrocarbon exploration in this region. Based on outcrop observations and the latest drilling, logging, and seismic data, we determine the sequences in the Maokou Formation within the eastern Sichuan Basin and investigate the formation filling process from deposition. The results indicate that rifting in the eastern Sichuan Basin began in the early to middle Middle Permian, as manifested by the initial rifting stage during the late depositional stage of the 1st member of the Maokou Formation (also referred to as the Mao 1 Member), and the significantly intensified activation of Nos. 15 and 16 basement faults during the early depositional stage of the Mao 2 Member. In response to the tensile stress in the N-S direction, the sedimentary landscapes of study area are transformed as characterized by southern platforms and northern rifts. Following the late depositional stage of the Mao 2 Member, the tectonic activity got further intensified in the study area, evolving into a period of continuous rifting development. This multi-stage tectonic and sedimentary differentiation is likely influenced by the episodic activities of the Emeishan large igneous province (ELIP), leading to the formation of multi-stage slope break zones. The Gufeng Member of the Maokou Formation in the Shizhu area, as well as the Cheng-20 and Zhang-12 well blocks, represents organic matter-rich deposits formed in low-lying areas of the carbonate platform. Meanwhile, the reservoirs of the high-energy shoal facies and the source rocks of the Gufeng Member in the low-lying areas create a favorable source rock-reservoir configuration. All these establish the areas as potential large-scale exploration region. Furthermore, the platform-margin shoal zone in well Cheng-23—Zhongxian County is identified as a natural gas play fairway.

Key words: Emeishan large igneous province (ELIP), rift evolution, sequence stratigraphy, natural gas, Maokou Formation, Sichuan Basin

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