Oil & Gas Geology ›› 2022, Vol. 43 ›› Issue (6): 1445-1458.doi: 10.11743/ogg20220613

• Petroleum Geology • Previous Articles     Next Articles

Geochemical characteristics and hydrocarbon resources potential of source rocks in Babei Sag, Yingen-Ejinaqi Basin

Yiwen Gao1(), Shiyan Hao1(), Qing Wang2, Weibo Wang1, Shaojing Jiang1, Qingxiong Fan3, Zhijun Chen1, Ye Zhou1   

  1. 1.Reseach Institute,Yanchang Petroleum (Group) Co. Ltd. ,Xi’an,Shaanxi 710075,China
    2.No. 6 Gas Production Plant,Changqing Oil Field Company,PetroChina,Xi'an,Shaanxi 710018
    3.Drilling Engineering Company,Yanchang Petroleum (Group) Co. Ltd. ,Yan'an,Shaanxi 716000,China
  • Received:2022-04-06 Revised:2022-09-10 Online:2022-11-21 Published:2022-11-21
  • Contact: Shiyan Hao E-mail:32952030@qq.com;463632928@qq.com

Abstract:

The source rocks and reservoirs in the Babei Sag, Yingen-Ejinaqi Basin, are assessed for geochemical characterization, effective source rock mapping and hydrocarbon potential analysis based on data from rock pyrolysis experiments of 1 143 mudstone samples and systematic tests of 38 mudstone samples from two local wells. The results show that potential source rocks are developed in mudstones of the Yingen Formation (K1y), Suhongtu Formation (K1s), the third, second and first members of the Bayingob Formation (K1b3, K1b2 and K1b1), and Carboniferous-Permian (C-P) systems in the sag. Among them, the latter four (K1b3, K1b2, K1b1 and C-P) have higher organic matter abundance with type Ⅱ2-typeⅢ kerogen of maturity and over-maturity. Higher plant made significant contribution to the organic carbon content in the source rocks and a weak reducing—weak oxidizing environment together with brackish water provided a setting for the source rocks to deposit. The source rocks in the sag are deemed effective when their TOC is no less than 0.80 % and threshold depth for hydrocarbon generation is 1 100 m. Based on these criteria, effective source rocks in the sag are mainly developed in K1b3, K1b2, K1b1 and C-P and have the largest thickness in two sedimentary centers (northern subsag and southern subsag). Good source rock conditions and active hydrocarbon shows indicate that the study area has good hydrocarbon exploration potential.

Key words: geochemical characteristics, source rock, petroleum resource potential, Babei sag, Yingen-Ejinaqi Basin

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