Geochemical characteristics and hydrocarbon potential of source rocks of the Upper Permian Linxi Formation in the Kundu-Taohaiyingzi area, NE China

• Published in: Oil shale (Tallinn, Estonia : 1984) Estonia : 1984), 2024-12, Vol.41 (4), p.237-256
• Main Authors: Li, Yihang, Zhang, Yujin, Fu, Xiuli, Lou, Renxing, Dong, Qingshui, Xin, Xiaochao, Huang, Youyou, Su, Yangxin, Bai, Yue
• Format: Article
• Language: English
• Subjects: Algae; Alkanes; Analysis; Aquatic plants; Basins (Geology); Carbon; Carbon content; continental shale; geochemical characteristics; Geochemistry; Geological surveys; Geology; hydrocarbon potential; Hydrocarbons; Information processing; Kerogen; linxi formation; Mudstone; Natural gas exploration; Oil and gas exploration; Organic carbon; Organic geochemistry; Organic matter; Outcrops; Permian; Petrology; Rocks; Sedimentary rocks; Shale; Shale gas; Shale oils; Shales; songliao basin; Stratigraphy; Surveys; Total organic carbon
• ISSN: 0208-189X; 1736-7492
• DOI: 10.3176/oil.2024.4.01

The extremely thick dark mudstone of the Permian Linxi Formation in the Kundu-Taohaiyingzi area of northeastern China is a promising potential area for shale gas prospecting in the periphery of the Songliao Basin. This study involved a geological field survey, outcrop sample collection, and comprehensive geochemical analysis to conduct an in-depth analysis of the organic matter enrichment and hydrocarbon generation potential of the dark mudstone of the target zone, using organic petrology and organic geochemistry. The results show that the thermal maturity of the dark mudstone of the Linxi Formation is in the mature to high-mature stage. The organic matter is dominated by type II kerogen and supplemented by type III kerogen, and the average total organic carbon content is 0.76%, classifying it as a medium-good source rock. The main peak of carbon numbers is primarily distributed between n[C.sub.17] and n[C.sub.19], with a smaller amount at n[C.sub.21]. The distribution of n-alkanes follows a pre-peakpattern characterized by medium and low carbon numbers, suggesting that the organic matter originates from aquatic plants, bacteria, and algae. Combined with the fact that the ratios of pristine and phytane (Pr/Ph) are mainly distributed in the range of 0.99-1.33, the sedimentary environment is a weakly reduced to weakly oxidized lacustrine bay. The systematic analysis of the source rocks of the Upper Permian Linxi Formation in the Kundu-Taohaiyingzi area indicates favorable prospects for shale gas exploration. Utilizing a comprehensive superposition method of geological information, this article identified the Yamen Gacha-Saihan Tala area as a potential area for shale gas exploration. Keywords: Songliao Basin, continental shale, Linxi Formation, geochemical characteristics, hydrocarbon potential.