陆相页岩油复杂多重孔隙流体动用模式与传质模拟研究

The continental shale oil reservoirs are characterized by strong heterogeneity, complex pore types and oil occurrence patterns. Oil transport in micro-nano pores is obviously affected by hydrocarbon-solid interaction, which leads to the inaccuracy of traditional oil and gas seepage theories and methods in describing the mobility pattern and flow law of shale oil. This research focuses on the key scientific problems in the study of shale oil mobility pattern and mass transfer simulation in shale multi-porosity media. By improving experimental methods and innovating theories, the pore structure properties and distribution rules of shale oil can be characterized, and the mobility characteristics of shale oil in different occurrence patterns in multiple pores can be revealed. Molecular simulation method is used to study transport mechanisms of liquid hydrocarbon including adsorption and velocity slip in micro-nano pores and a characterization method of shale oil flow parameters considering heterogeneous distribution of shale pores is constructed. On this basis, the mathematical models of shale oil mass transfer in kerogen-inorganic pores are established considering the distribution of organic matters and verified by results of physical experiments. Finally, combining the distribution of natural micro-fractures, the mass transfer simulation method of shale oil with different mobility patterns in multi-porosity media is formed, and the mobility limit and seepage law of shale oil with different occurrence patterns in multi-porosity media are explored to provide theoretical basis for effective development of continental shale oil in China.

陆相页岩油藏非均质性强、孔隙类型和原油赋存方式复杂，微纳米孔隙内原油运移受烃-固相互作用影响明显，导致传统油气渗流理论无法准确描述页岩油的动用模式和流动规律。本课题针对页岩复杂多重孔隙内原油动用模式和传质模拟中的关键科学问题，通过实验改进和理论创新，表征页岩油孔隙结构特征和分布规律，揭示多重孔隙内不同赋存方式页岩油动用特征；利用分子模拟方法，研究微纳米孔内液态烃吸附、速度滑移等运移机制，构建考虑孔隙非均匀分布的页岩油流动参数表征方法；在此基础上，考虑有机质分布建立干酪根-无机基质页岩油传质数学模型，利用实验结果进行验证；最后结合天然微裂缝分布，形成页岩油多重孔隙不同动用模式的传质模拟方法，探索多重孔隙不同赋存方式页岩油的动用界限和渗流规律，为我国陆相页岩油有效开发提供理论依据。

多重多尺度孔隙介质是陆相页岩油藏重要的储层特征。由于水力压裂的复杂性导致页岩孔隙介质和流体运移规律的表征难度增大。明确不同尺度不同类型页岩孔隙介质内流体运移机制和动用模式对提高页岩油宏观渗流模拟可靠性和制定合理的开发方案具有重要意义。本项目首先采用物理实验方法研究了不同页岩孔隙介质变化规律，明确了水力压裂对页岩孔隙结构的影响机制，揭示了不同孔隙介质改造前后的可动界限。然后，基于分形几何理论，构建多重孔隙介质耦合表观渗透率模型，研究不同孔隙介质内微观运移机制对渗流特征的影响规律，明确了不同孔径分布下有机和无机孔隙内流体运移机制和表观渗透率的综合特征。在宏观尺度页岩油井模拟研究方面，首先构建了考虑基质-裂缝耦合的页岩油压裂井流动数学模型，通过解析和数值求解方法，研究了不同影响因素下页岩油井压力和产能变化规律及其影响因素，利用改进数理方法明确页岩油井产能影响主控因素，明确了不同产能影响因素的影响程度。同时，耦合自动历史拟合方法和产能评价模型，解决了页岩油井改造缝网参数获取困难的问题，并基于地质工程一体化评价指标体系实现对压裂潜力的预测，指导页岩油井的压裂施工设计和压后效果评价。.基于本项目的研究，深化了页岩油井压裂后不同孔隙介质内流体动用程度的认识，提高了页岩多重介质耦合表观渗透率的计算准确性，为提高页岩油藏宏观流动模拟方法的可靠性提供了理论基础；同时，也为页岩油藏的地质工程一体化压裂设计方案的制定提供了理论指导。