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
Wenzhong HAN1,2, Xianzheng ZHAO2, Xiugang PU2, Shiyue CHEN1(), Hu WANG2, Yan LIU3, Zhannan SHI2, Wei ZHANG2, Jiapeng WU2
1. School of Earth Science and technology, China University of Petroleum (East China), Qingdao 266580, China 2. Dagang Oil Field Company of PetroChina, Tianjin 300280, China 3. Key Laboratory of Exploration Technologies for Oil and Gas Resources (Ministry of Education), Yangtze University, Wuhan 430100, China
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 km2. 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.
. [J]. Frontiers of Earth Science, 2021, 15(2): 423-437.
Wenzhong HAN, Xianzheng ZHAO, Xiugang PU, Shiyue CHEN, Hu WANG, Yan LIU, Zhannan SHI, Wei ZHANG, Jiapeng WU. 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. Front. Earth Sci., 2021, 15(2): 423-437.
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