The prediction of rock permeability is important in the extraction of oil/gas from tight reservoirs. Permeability is determined by connected pores and their distribution in rocks. The existence of pore can induce stress concentration around pore surface which affects pore strains. In common permeability models, volumetric pore strains are used to quantify the permeability evolution during gas production but pore strain solutions exclude the impact of stress concentration. In this study, the stress concentration around pore surface was considered and corresponding pore surface displacements were calculated. Different from solutions of volumetric pore strain, solutions of stress concentration and pore surface displacement have close relationship with pore geometry. Based on SEM images of tight rocks, the pore shape was assumed as ellipse. An analytical solution for the surface displacement of an ellipse pore was derived and substituted into the permeability definition. Different from common permeability models, this novel permeability model includes pore geometry property. This geometry-based permeability model was verified by experimental data. The comparison between the common model and this geometry-based model was also conducted. The sensitivity study was conducted to investigate impacts of pore geometry and stress variation on permeability evolution. It was illustrated that this geometry-based model is valid and its performance of permeability prediction for tight rocks is better than that of common model. This is because the important factors, such as pore geometry size and stress orientation, are incorporated explicitly. The advantage of this geometry-based model is that the impact of stress orientation (α) on permeability is involved so this geometry-based model is able to predict permeability of reservoirs after hydraulic fracturing where the stress orientation commonly changes.

岩石渗透率的预测对于从致密油藏中提取油气至关重要。渗透率取决于连通的孔隙及其在岩石中的分布。孔的存在会引起孔​​表面应力集中，从而影响孔应变。在常见的渗透率模型中，使用体积孔隙应变来量化天然气生产过程中的渗透率演变，但孔隙应变解却排除了应力集中的影响。在这项研究中，考虑了孔表面周围的应力集中并计算了相应的孔表面位移。与体积孔隙应变的解决方案不同，应力集中和孔隙表面位移的解决方案与孔隙几何形状密切相关。根据致密岩石的SEM图像，孔隙形状被假定为椭圆形。得出了椭圆孔表面位移的解析解，并将其代入渗透率定义中。与常见的渗透率模型不同，这种新颖的渗透率模型具有孔隙几何特性。通过实验数据验证了这种基于几何的渗透率模型。还进行了通用模型与基于几何的模型之间的比较。进行了敏感性研究，以研究孔隙几何形状和应力变化对渗透率演化的影响。结果表明，这种基于几何的模型是有效的，其致密岩渗透率预测性能优于普通模型。这是因为重要因素（例如孔几何尺寸和应力方向）已明确纳入。α）涉及渗透率，因此该基于几何的模型能够预测水力压裂后应力方向通常发生变化的储层的渗透率。