Abstract The inorganic pores, organic pores, and kerogen matrix are important media to store water and oil in shale rocks. We present a vacuum imbibition method to identify the volume of water and oil in these media. Before the experiments, comprehensive rock characterizations were carried out on shale samples from Shahejie Formation combining various methods including N2 adsorption, scanning electron microscope (SEM), X-ray diffraction, and RockEval pyrolysis. Total organic carbon (TOC) accounts for 1.59–5.97% of total rock weight. Kerogen thermal maturity (Ro) of the studied samples is 0.62–1.05%. Then, vacuum imbibition experiments were conducted on shale samples using water and n-dodecane. The accurate volumes of water in organic pores, oil in inorganic pores and organic pores, and the volume of dissolved oil were determined from vacuum imbibition experiments. The effects of Ro on shale storage were analyzed. Furthermore, novel mathematical models of oil and water vacuum imbibition in shale were proposed. The water imbibition in inorganic pores is a capillary flow. The oil imbibition in shale includes capillary flow in pore structures and diffusion in kerogen. The pore-kerogen double diffuse layer (PKDDL) physical model was proposed for the mechanisms of the hydrocarbon mass transfer between pore structures and kerogen. The capillary pressure and the dissolution rate constants were obtained by matching mathematical models with experimental results. This study provides new methods to evaluate the water and oil storage and transfer in organic-rich shale and advances the crucial mechanisms for the evaluation and development of shale reservoirs.

中文翻译：

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真空自吸法研究富有机质页岩水油储运

摘要 无机孔、有机孔和干酪根基质是页岩中储水储油的重要介质。我们提出了一种真空吸入法来确定这些介质中水和油的体积。实验前，结合N2吸附、扫描电子显微镜（SEM）、X射线衍射和RockEval热解等多种方法对沙河街组页岩样品进行了综合岩石表征。总有机碳 (TOC) 占岩石总重量的 1.59-5.97%。研究样品的干酪根热成熟度 (Ro) 为 0.62-1.05%。然后，使用水和正十二烷对页岩样品进行了真空吸渗实验。有机孔中水、无机孔和有机孔中油的准确体积，溶解油的体积由真空渗吸实验确定。分析了 Ro 对页岩储量的影响。此外，提出了新的页岩油水真空自吸数学模型。无机孔隙中的吸水是毛细管流动。页岩中的吸油包括孔隙结构中的毛细流动和干酪根中的扩散。提出了孔隙-干酪根双扩散层（PKDDL）物理模型来研究孔隙结构与干酪根之间的烃类传质机制。毛细管压力和溶解速率常数是通过将数学模型与实验结果相匹配而获得的。