Fine-grained rock fabric facies classification and its control on shale oil accumulation: a case study from the Paleogene Kong 2 Member, Bohai Bay Basin

• Published in: Frontiers of earth science Vol. 15; no. 2; pp. 423 - 437
• Main Authors: HAN, Wenzhong, ZHAO, Xianzheng, PU, Xiugang, CHEN, Shiyue, WANG, Hu, LIU, Yan, SHI, Zhannan, ZHANG, Wei, WU, Jiapeng
• Format: Journal Article
• Language: English
• Published: Beijing Higher Education Press 01.06.2021; Springer Nature B.V
• Subjects: Accumulation; Bohai Bay Basin; Classification; Core analysis; Core sampling; Coring; Earth and Environmental Science; Earth Sciences; fabric facies; fine grained deposits; Fluorescence; Geochemistry; Horizontal wells; Hydrocarbons; Laboratory tests; lithologic facies; Logging; Mineral composition; Oil and gas exploration; Oil exploration; Oil shale; Optimization; organic facies; Paleogene; Physical properties; Research Article; Rocks; Sedimentary facies; Sedimentary rocks; Sedimentary structures; Seismic surveys; Shale; Shale oil; Shales; Total organic carbon; Bohai Bay; organic facies; fine grained deposits; lithologic facies; Bohai Bay Basin; fabric facies
• ISSN: 2095-0195; 2095-0209
• DOI: 10.1007/s11707-020-0867-4

Lacustrine shale oil resources in China are abundant, with remarkable exploration breakthroughs being achieved. Compared to marine shale oil in North America, efficient exploration of lacustrine shale oil is more difficult; thus, selecting favorable layer and optimization zone for horizontal wells is more important. In this study, based on systematic coring of approximately 500 m fine-grained deposits of the Kong 2 Member, combining laboratory tests and log data, source rock geochemistry and reservoir physical properties, the favorable rock fabric facies for oil accumulation was analyzed and classified. First, the dominant lithologic facies, organic facies, and bed combination facies were determined based on mineral composition from logging, total organic content (TOC), and sedimentary structure. Secondly, 10 fabric facies were classified by combining these three facies, with 4 fabric facies were found to have high TOC content, high total hydrocarbon, and strong fluorescence features, indicating good shale oil enrichment. Thirdly, the distribution of the upon good fabric facies was identified to be located at the top of the Kong 2 Member, with evidences of seismic resistivity inversion, thermal maturity, structure depth, and strata thickness. And the favorable facies were found to be stably distributed lateral at the area of about 100 km 2. High oil flow has been detected at this layer within this area by several wells, including horizontal wells. The exploratory study of fabric facies classification and evaluation provides a new research idea for lacustrine shale oil exploration and effectively promotes breakthroughs in lacustrine shale oil exploration in Bohai Bay Basin.