Xinjiang Petroleum Geology ›› 2025, Vol. 46 ›› Issue (6): 684-692.doi: 10.7657/XJPG20250604

• OIL AND GAS EXPLORATION • Previous Articles     Next Articles

Microscopic Occurrence and Production Dynamics of Shale Oil in Lucaogou Formation, Jimsar Sag, Junggar Basin

LIU Jin1,2a,3(), BAI Lei2a,3,4, ZHANG Baozhen2a, WEI Chao1, LEI Haiyan2b, DENG Yuan2a, CAO Jian1()   

  1. 1. School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu 210023, China
    2. PetroChina Xinjiang Oilfield Company, a.Research Institute of Exploration and Development; b.Mahu Exploration and Development Project Department, Karamay, Xinjiang 834000, China
    3. Xinjiang Key Laboratory of Shale Oil Exploration and Development, Karamay, Xinjiang 834000, China
    4. School of Petroleum Engineering, China University of Petroleum (Beijing), Beijing 102249, China
  • Received:2025-04-21 Revised:2025-07-14 Online:2025-12-01 Published:2025-12-05
  • Contact: CAO Jian E-mail:liujin2015@petrochina.com.cn;jcao@nju.edu.cn

Abstract:

Complex microscopic occurrence and unclear production dynamics of shale oil in continental saline lacustrine basins challenge the study of shale oil enrichment theory and development law. Taking the Lucaogou formation in the Jimsar sag of Junggar Basin as an example, this paper characterizes the fluid occurrence state and mobility in the shale reservoirs using the techniques such as nuclear magnetic resonance, confocal laser scanning microscopy, argon ion polishing, and scanning electron microscopy, and validates against the monitoring results of produced fluid from individual wells in the pilot test area. The results show that the microscopic occurrence of the shale oil is characterized by oil fully saturating nanopores and both oil and water coexisting in sub-micron to micron-sized pores, with light and heavy components in hydrocarbons arranged in an onionskin pattern. The natural depletion of shale oil prefers the light hydrocarbon components stored in sub-micron to micron-sized pores, where free water is involved in the fluid flow. Changes in crude oil properties and produced water during well production represent effective responses to the microscopic fluid occurrence state. Shale oil well production is featured with by long-term water production and sequential producing of light and heavy components.

Key words: Junggar Basin, Jimsar sag, Lucaogou formation, shale oil, microscopic occurrence state, dynamic response

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