@article{Pu2026, 
author = {Xiugang Pu and Guochao Xia and Jiangchang Dong and Zhannan Shi and Wenzhong Han and Qianru Shi and Wei Zhang and Yueqi Dong and Xiongying Dong},
title = {Multi-source hydrocarbon accumulation in the faulted and deeply depressed Tangdong area, Qikou Sag, Bohai Bay Basin},
year = {2026},
journal = {Energy Geoscience},
volume = {7},
number = {2},
keywords = {Oil-source rock correlation, Multi-source hydrocarbon accumulation, Petroleum geochemistry, Source rock, Deeply depressed area, Qikou sag, Exploration well emplacement},
url = {https://www.sciopen.com/article/10.1016/j.engeos.2026.100522},
doi = {10.1016/j.engeos.2026.100522},
abstract = {Based on organic geochemical analysis data, this study examined the characteristics of multi-source hydrocarbon accumulation in the Tangdong area of Qikou Depression, Bohai Bay Basin. The results indicate that the Tangdong area contains four source rock sequences: the third member of the Dongying Formation (Ed3), the middle and lower sub-members of the first and third member of Shahejie Formation (Es1M, Es1L, Es3). Both the salinity of sedimentary water bodies and the contribution of bacteria in the four source rock sequences gradual increase in the order of Es3, Es1M, Es1L and Ed3, as indicated by the Ga/C30H, ETR, sterane/C30 hopane, C24TeT/C26TT, C23TT/C30H, and the carbon isotope data of group components. Additionally, certain quantities of 4-methylsterane have been detected in source rocks in the Es3, Es1M, and Ed3, suggesting the special contribution of dinoflagellates to these source rocks. Based on biomarker parameters and carbon isotope data, the crude oil can be categorized into classes A to D, which show complex multi-source accumulation characterized by different sources in the same well and even in the same layer. Class A crude oil occurring in the higher part of the Ed3 originates from source rocks in the Es1L and Es3. Class B oil existing in the lower part of the Ed3 is derived from source rocks in the Ed3. Class C oil found in the Es1U is sourced from source rocks in the Es1M. Class D oil present in the Es1L is contributed indigenously by the source rocks in the Es1L, establishing this unit as a lithologic hydrocarbon reservoir with source rocks and reservoirs in the same layer. Under the guidance of the understanding of multi-source hydrocarbon accumulation, currently, three wells have been drilled, all yielding satisfactory outcomes.}
}