考虑应力敏感的致密储层油水两相相对流动能力分形数值模拟方法

A Numerical Simulation Method for Oil-Water Two-Phase Relative Flow Capacity in Tight Reservoirs Considering Stress Sensitivity Effect

在应用分形理论和毛管束模型的基础上,建立了考虑应力敏感性的致密储层油水两相相对渗透率模型。通过定义归一化油水相对渗透率,研究了有效应力、弹性模量和孔隙度对致密储层油水两相相渗曲线的影响。模型的预测结果与实验数据的吻合程度高,验证了模型的有效性。理论分析结果表明:有效应力与束缚水饱和度、剩余油饱和度呈负相关。随着有效应力的增大,油水两相的相对渗透率向中间收缩,共渗区域减小;随着弹性模量的降低,孔隙介质的变形量、束缚水和残余油饱和度均增大;孔隙度对油水两相的相对渗透率影响较小。建立的模型可以准确描述应力作用下致密储层油水两相的渗流特征。

A oil-water relative permeability model for tight reservoirs considering stress sensitivity was established on the basis of fractal theory and capillary bundle model.The effects of effective stress,elastic modulus and porosity on the oil-water relative permeability curve of tight reservoirs were studied by defining the normalized oil-water relative permeability.The high agreement degree between the predicted results of the model and the experimental data validates the effectiveness of the model.The theoretical analysis results indicate that effective stress is negatively correlated with irreducible water saturation and remaining oil saturation.As the effective stress increases,the relative permeability of oil and water shrinks towards the middle,and the co-seepage area of oil and water decreases.As the elastic modulus decreases,the deformation,irreducible water saturation and residual oil saturation of the porous medium all increase.The influence of porosity on the relative permeability of oil and water is relatively small.The established model can accurately describe the two-phase seepage characteristics of oil and water in tight reservoirs with stress.