Special Oil & Gas Reservoirs ›› 2024, Vol. 31 ›› Issue (2): 37-46.DOI: 10.3969/j.issn.1006-6535.2024.02.005

• Geologic Exploration • Previous Articles     Next Articles

Mechanism of Overpressure Formation in the Youquanzi Oilfield in western Qaidam Basin

Han Tianhua1,2, Liu Chenglin1,2, Tian Jixian3, Yang Taozheng1,2, Feng Dehao1,2, Li Guoxiong1,2   

  1. 1. National Key Laboratory of Petroleum Resources and Engineering of China University of Petroleum (Beijing), Beijing 102249, China;
    2. China University of Petroleum (Beijing), Beijing 102249, China;
    3. China Petroleum Exploration and Production Research Institute, Beijing 100083, China
  • Received:2023-02-06 Revised:2024-01-04 Online:2024-04-25 Published:2024-07-26

Abstract: Overpressure is widely developed in the Cenozoic formation of the Youquanzi Oilfield in western Qaidam Basin, and the identification of overpressure genesis has great significance for the study of oil-gas migration and reservoir formation. The measured pressures, logging curves, acoustic velocity - density cross plot, overpressure genesis comprehensive analysis method and overpressure compartment mode for the Youquanzi Oilfield were comprehensively analyzed. The results show that the negative pressure, normal pressure, overpressure and strong overpressure systems were longitudinally developed in the Cenozoic Formation of the Youquanzi Oilfield; the pressure coefficient of the overpressure system was generally greater than 1.3, and the pressure coefficient of some overpressure points was greater than 1.73, showing the characteristics of strong overpressure; overpressure in this area, the main controlling factors were the uneven compaction, tectonic extrusion and hydrocarbon generation; the oil-gas migration was in line with the overpressure compartment mode; the oil and gas were migrated to the Nanyi Mountain Area due to overpressure. The study result clarifies the oil-gas migration direction of the Yauquanzi Oilfield and is of guiding significance to the study of oil and gas reservoirs in western Qaidam Basin and similar regions.

Key words: overpressure compartment, pressure coefficient, uneven compaction, hydrocarbon generation, tectonic extrusion, Youquanzi Oilfield

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