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0 2026012202

DOI: https://doi.org/10.11698/PED.20250583

Enrichment mechanism and optimal in-situ conversion recovery method of lacustrine low- to medium-maturity shale oil

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  • 1. ZWZ Academician Research Studio, PetroChina Research Institute of Petroleum Exploration & Development, Beijing 100083, China;
    2. PetroChina Research Institute of Petroleum Exploration & Development, Beijing 100083, China;
    3. State Key Laboratory of Continental Shale Oil, Daqing 163712, China;
    4. National Engineering Laboratory for Exploration and Development of Low-Permeability Oil & Gas Fields, Xi’an 710018, China;
    5. Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China;
    6. School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China

Received date: 2025-10-30

  Revised date: 2026-01-10

  Online published: 2026-01-22

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Abstract

In-situ heating conversion is the most practical extraction method for lacustrine low-to-medium maturity shale oil. However, the energy output-input ratio (Eout/Ein) must exceed the economic threshold to achieve commercial development. This paper systematically investigates the mechanism of super-rich accumulation of organic matter in continental shale, sweet spot evaluation, optimal heating windows, and appropriate well types and patterns from the perspectives of enhancing energy output and reducing energy input. (1) The super-rich accumulation of organic matter in lacustrine shale is primarily controlled by the intensity, frequency, and preservation of external material inputs, and is related to moderate volcanic and hydrothermal activities, marine transgressions, and radioactive materials, with organic matter abundance ≥6%. (2) The quality of organic-rich intervals is related to the type of source material and hydrocarbon generation potential. The in-situ conversion-derived hydrocarbon quality index (HQI) is established, and the zones exhibiting HQI ˃450 are defined as sweet spots. (3) Considering the characteristics of the organic matter conversion material field and seepage field, the temperature interval 300 °C-370 °C is recommended as the optimal heating window for the Chang 73 sub-member in the Ordos Basin. Based on the advantages of thermal conductivity, permeability, and hydrocarbon expulsion efficiency along the bedding direction during shale heating, the “horizontal well heating + vertical well development” scheme is proposed, which has demonstrated significant enhancement in both recovery factor and energy output-input ratio, making it the optimal in-situ conversion process. The research findings provide a theoretical and technical foundation for the economical and efficient development of low- to medium-maturity shale oil.

Key words： lacustrine low-to-medium maturity shale oil; in-situ heating conversion; optimal heating window; horizontal well heating + vertical well development; energy output-input ratio; super-rich accumulation of organic matter; renewable energy

Cite this article

ZHAO Wenzhi, LIU Wei, BIAN Congsheng, XU Ruina, WANG Xiaomei, LV Weifeng, JIN Jiafeng, YAO Chuanjin, XIONG Chi, LI Ruirui, LI Yongxin, DONG Jin, GUAN Ming, BIAN Leibo . Enrichment mechanism and optimal in-situ conversion recovery method of lacustrine low- to medium-maturity shale oil[J]. Petroleum Exploration and Development, 0 : 2026012202 . DOI: 10.11698/PED.20250583

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