Main Controlling Factors and Development Practice of Shale Oil Sweet Spots in the Lucaogou Formation, Jimsar Sag, Junggar Basin

doi:10.7657/XJPG20250601

Abstract

Abstract:

The Permian Lucaogou formation in the Jimsar sag, Junggar Basin, represents one of the most significant continental shale oil plays in China. However, uncertainties remain regarding the primary geological controls of “sweet spots”, incomplete evaluation frameworks, and discontinuous distribution of productive intervals. Clarifying the formation mechanisms and identification criteria of the sweet spots is critical for advancing shale oil exploration theory and guiding efficient development. Based on core, well logging, and experimental data, this study systematically investigates the controlling factors of shale oil sweet spots in the Lucaogou formation from four dimensions (reservoir capacity, oil-bearing capacity, mobility, and fracability). The results indicate that the Lucaogou formation can be divided into upper, middle, and lower sweet-spot intervals, among which the middle interval remains largely undeveloped yet holds substantial potential. Siltstone and calcareous-felsic shale which are characterized by abundant macropores, high free hydrocarbon content, and strong mobility constitute the most favorable lithofacies. Intervals with moderate total organic carbon (TOC) content, moderate maturity, and high brittle-mineral content are more conducive to forming fracable sweet spots. A four-property coupling evaluation highlights the middle interval as a prime development target which is further validated by the high-yield performance of Well JHW85-71. This study provides a scientific foundation for sweet spot identification and development planning of shale oil in the Lucaogou formation in the Jimsar sag.

Key words: Junggar Basin, Jimsar sag, Lucaogou formation, shale oil, sweet-spot interval, controlling factor, development strategy

CLC Number:

P618.12

JIN Zhijun, CAO Yan, ZHANG Hong, TANG Yong, QIN Zhijun, LIU Kouqi, LIANG Chenggang, LI Guanfang, HE Wenjun. Main Controlling Factors and Development Practice of Shale Oil Sweet Spots in the Lucaogou Formation, Jimsar Sag, Junggar Basin[J]. Xinjiang Petroleum Geology, 2025, 46(6): 647-658.

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