Oil & Gas Geology ›› 2021, Vol. 42 ›› Issue (2): 443-455.doi: 10.11743/ogg20210214

• Petroleum Geology • Previous Articles     Next Articles

Geological characteristics and shale oil exploration of Es3(1) in Qikou Sag, Bohai Bay Basin

Lihong Zhou(), Guomeng Han, Fei Yang, Jianying Ma, Liangang Mou, Kejia Zhou, Changli Wang, Lina Meng   

  1. Dagang Oilfield Branch Company, PetroChina, Tianjin 300280, China
  • Received:2020-04-03 Online:2021-04-28 Published:2021-04-21

Abstract:

The high and stable industrial shale oil flow from the first submember of the third member of Shahejie Formation (Es3(1)) in Qikou Sag, Bohai Bay Basin, reveals a possible 100 million tons of oil resource in the lacustrine shale of the member and serves as a significant reference for shale oil exploration in the whole Shahejie Formation of the basin.Based on a comprehensive study of sedimentary setting, lithology, reservoir properties, brittleness and oil-bearing property of the shale series in the member, we found that the shale series are of semi-deep lake-deep lake environment and characterized by well-developed pores and fractures, high brittleness, low reservoir sensitivity and high oil-gas bearing potential.They are favorable for hydrocarbon generation and accumulation and can be easily stimulated.Longitudinally, the member can be divided into 6 sweet-spot sections, namely sections C1 to C6 downwards of 7 to 96 m thick and 434 m in total.Horizontally, the sections are distributed in areas from 87.4 to 194.3 km2 with a cumulative area of 256 km2.Preliminary assessment using volumetric oil content method indicates the sections have a resource of 4.1×108 t.Guided by the development strategy of "using old wells to control the range of sweet spots and horizontal wells to increase production", two highly deviated wells, Wells Bin 60-56 and F38x1 were tested with industrial oil flows.Deploy horizontal well exploration for C1 sweet spot, Well QY10-1-1 was tested with 100 equivalent tons of hydrocarbon per day.Furthermore, Bin56-1H produced 3 043.11 t in total after 206 days of production, and the reverse drainage rate was 7.77%, indicating a major breakthrough in the shale oil exploration of Es3(1) in Qikou Sag, Bohai Bay Basin.

Key words: depositional setting, sweet spot evaluation, shale oil, the first submember of the third member of Shahejie Formation, Qikou Sag, Bohai Bay Basin

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