Earth Science Frontiers ›› 2024, Vol. 31 ›› Issue (2): 284-298.DOI: 10.13745/j.esf.sf.2023.5.33

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Can hydrocarbon source rock be uranium source rock?—a review and prospectives

LIU Chao1,2,3(), FU Xiaofei1,3,*(), LI Yangcheng4, WANG Haixue1,3, SUN Bing1, HAO Yan1, HU Huiting1, YANG Zicheng1,3, LI Yilin1,3, GU Shefeng4, ZHOU Aihong4, MA Chenglong5   

  1. 1. Institute of Unconventional Oil and Gas, Northeast Petroleum University, Daqing 163318, China
    2. Institute of Applied Technology, Northeast Petroleum University, Daqing 163318, China
    3. Ministry of Education Key Laboratory of Continental Shale Hydrocarbon Accumulation and Efficient Development, Northeast Petroleum University, Daqing 163318, China
    4. Daqing Oilfield Company Ltd., Daqing 163712, China
    5. Liaohe Oilfield Company Research Institute of Petroleum Exploration & Development, Panjin 124010, China
  • Received:2023-01-26 Revised:2023-04-27 Online:2024-03-25 Published:2024-04-18

Abstract:

The coexistence of hydrocarbon source rocks and sandstone-hosted uranium (U) deposits in the same basin has been widely reported. Hydrocarbon source rock contributes to uranium precipitation and enrichment by providing oil and gas; whereas, whether it can be a source of uranium supply is of great relevance as to weather uranium prospecting should expand deep into the basin. This study reviews relevant domestic and international studies and offers perspectives on this topic, focusing on three key issues: migration potential of uranium in source rock, possible ways of uranium transport by formation fluids, and mechanisms of uranium precipitation and accumulation. Hydrothermal modeling results show that uranium migration can occur during hydrocarbon generation and expulsion, and the migrated-uranium, probably a mix of U(IV) and U(VI), is likely transported by both hydrocarbon-bearing formation water and oils. The transported-uranium precipitates due to a decrease of uranium solubility and decomposition of the transport fluids caused by a decrease of temperature and pressure and change of pH and Eh; the uranium precipitates can also redissolve in oxygen-rich formation water. The main perspectives are: (1) the amount of migrated-uranium is uncertain, and the mechanism and laws of U migration are still unclear, thus further modeling experiments on source rock-uranium system is recommended to understand the kinetics of uranium migration. (2) Up to now, little is known about the dominant U mobile forms and their thermodynamic properties and distribution between hydrocarbon-bearing formation water and oil, thus, in-situ thermal testing via thermal simulation experiments is recommended to address this issue. (3) During uranium upward transport, changes in temperature, pressure, Eh, and organic/inorganic components of the transport fluids control uranium geochemistry, thereby, in order to understand uranium geochemistry and its controlling factors under different conditions, multi-variable simulation experiments on hydrocarbon-uranium transport is suggested.

Key words: hydrocarbon source rocks, source of uranium, oil and gas, sandstone-hosted uranium deposit, mobile, metallogenetic mechanism

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