Title: Paleoenvironment and petroleum potential of the lacustrine shales in the Lower Cretaceous Shahezi Formation of the Southern Songliao Basin, NE China

Authors: Zhengjian Xu; Shu Jiang; Xiaodong Hu; Wenchao Zhang; Xiaogang Li; Shaohua Xu; Nini Zhang

Addresses: Chongqing Key Laboratory of Complex Oil and Gas Field Exploration and Development, Chongqing University of Science and Technology, Chongqing 401331, China; Chongqing Institute of Geology and Mineral Resources, Chongqing 401120, China; Key Laboratory of Tectonics and Petroleum Resources, China University of Geosciences, Ministry of Education, Wuhan 430074, China; Key Laboratory of Sedimentary Basin and Oil and Gas Resources, Ministry of Natural Resources, Chengdu 610081, China ' Key Laboratory of Tectonics and Petroleum Resources, China University of Geosciences, Ministry of Education, Wuhan 430074, China; Energy and Geoscience Institute, University of Utah, Salt Lake City, 84108, USA ' Chongqing Key Laboratory of Complex Oil and Gas Field Exploration and Development, Chongqing University of Science and Technology, Chongqing 401331, China ' Chongqing Key Laboratory of Complex Oil and Gas Field Exploration and Development, Chongqing University of Science and Technology, Chongqing 401331, China ' Chongqing Key Laboratory of Complex Oil and Gas Field Exploration and Development, Chongqing University of Science and Technology, Chongqing 401331, China ' Chongqing Key Laboratory of Complex Oil and Gas Field Exploration and Development, Chongqing University of Science and Technology, Chongqing 401331, China ' Geologic Exploration and Development Research Institute, Chuanqing Drilling Co., Ltd., CNPC, Chengdu 610051, China

Abstract: The occurrence of conventional and unconventional hydrocarbons is directly determined by organic matter (OM)-rich shales in fault-controlled sedimentary basins. Through integrated analyses of organic petrology, element concentrations, bulk organic geochemical characteristics, hydrocarbon generation, and expulsion of the Shahezi shales, we have conducted comprehensive studies on the paleoenvironment, OM source, and petroleum potential of the Shahezi shales: 1) the Shahezi deposition occurred under a cold and semi-humid to semi-arid paleoclimate, and sub-reducing to reducing redox conditions, favourable for OM preservation; 2) the OM origins of shales are primarily a mixture of aquatic microorganisms and terrestrial higher plants; 3) the shales demonstrate a fair to excellent source rock potential; 4) oil generation began around 130 Ma, while gas generation started around 105 Ma; 5) the shales have reached the hydrocarbon expulsion threshold; 6) the occurrence of burial-deep tight gas reservoirs, is predominantly controlled by the outer boundary of the shale distribution. [Received: December 29, 2023; Accepted: January 24, 2024]

Keywords: lacustrine shale; paleoenvironment; organic matter origin; petroleum potential; Shahezi Formation; Southern Songliao Basin; China.

DOI: 10.1504/IJOGCT.2024.139533

International Journal of Oil, Gas and Coal Technology, 2024 Vol.36 No.1, pp.1 - 36

Received: 22 Dec 2023
Accepted: 24 Jan 2024
Published online: 03 Jul 2024 *

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