Flow characteristics of shale oil and their geological controls: A case study of the Lucaogou Formation in the Jimsar Sag, Junggar Basin

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The Lucaogou Formation in Jimsar has a significant development potential due to its massive shale oil resources. Nevertheless, the complex and heterogeneous lithology, coupled with unclear flow mechanisms, poses a challenge in effectively predicting its development potential. Therefore, it is crucial to clarify the flow characteristics of shale oil and its controlling factors. In this study, we used a flow simulation experiment to investigate the flow characteristics of different samples under various temperatures and confining stresses and quantitatively evaluated flow characteristics using threshold pressure gradient and total loss of flow rate. Additionally, by combining scanning electron microscopy and mercury intrusion capillary pressure techniques for pore structure characterization, and the relationship between microscopic pore structure and flow parameters was discussed. The findings indicate that rock composition and pore throat structure collaboratively control shale oil flow. Mesopores and macropores primarily develop between dolomite or albite, leading to well-developed pore throat structure with larger average throat radius, lower displacement pressure, and better reservoir quality, enhancing shale oil flowability. Dolomitic siltstone often exhibits these characteristics, making it a favorable lithology for shale oil flow. This study reveals the flow mechanism of shale oil under the action of reservoir physical properties, material compositions, temperatures and confining stresses, summarizes the geological characteristics of advantageous reservoirs. It provides theoretical support for layer selection and efficient development of shale oil reservoirs in the Lucaogou Formation of the Jimsar.