基于分子动力学的页岩气储层表观渗透率预测模型研究

Study on prediction model of apparent permeability of shale gas reservoir based on molecular dynamics

页岩气储层表观渗透率的准确预测一直是行业面临的重大挑战,主要由于其复杂的孔隙结构和气体分子在多尺度上的输运行为,传统宏观渗透率模型难以应对这种复杂性。为解决这一问题,本研究融合了微观分子动力学模拟与宏观流体力学理论,提出了一种多尺度模型。通过分子动力学模拟深入探讨气体分子在纳米孔隙中的扩散、吸附及分子间相互作用,揭示了微观尺度的输运机制。基于模拟得到的气体分子扩散系数、吸附量和平均自由程等关键参数,本研究建立了一个修正的表观渗透率模型,从而更准确地预测气体在实际储层条件下的宏观流动行为。此外,模型通过实验数据验证和校准,确保其准确性与适用性。最终,该模型为页岩气的有效开发和产能评估提供了重要的理论支持,并为复杂孔隙介质中的气体输运研究提供了新的视角。

Accurate prediction of the apparent permeability of shale gas reservoirs has been a major challenge for the industry,mainly due to its complex pore structure and the transport behavior of gas molecules on multiple scales,and the traditional macroscopic permeability model is difficult to cope with this complexity.To address this issue,this study integrates microscopic molecular dynamics simulations with macroscopic hydrodynamics theory to propose a multi-scale model.The diffusion,adsorption and intermolecular interactions of gas molecules in nanopores are deeply explored through molecular dynamics simulations,revealing the transport mechanism at the microscopic scale.Based on the key parameters obtained from the simulations,such as the diffusion coefficient,adsorption,and mean free range of the gas molecules,a modified apparent permeability model is developed in this study,which can more accurately predict the macroscopic flow behavior of the gas under the actual reservoir conditions. In addition, the model is validated and calibrated by experimental data to ensure its accuracy and applicability. Ultimately, the model provides important theoretical support for the effective development and capacity assessment of shale gas, and offers a new perspective for the study of gas transport in complex pore media.