考虑局部渗流的Biot孔隙弹性模型改进

Modification of Biot Poroelastic Model by Considering Local Seepage

因井孔声场受储层渗透性影响,故声波测井可应用于储层渗透率评价。目前描述孔隙介质波动的经典Biot孔隙弹性模型明显低估了岩石中波的衰减。为解决这一问题并将声波测井应用于储层渗透率评价,在经典Biot模型基础上考虑局部渗流对声波衰减的影响,对经典Biot模型进行修正,将修正模型用于井孔声场模拟,分析利用声波测井数据反演地层渗透率的可行性。与实验数据对比表明,修正模型计算的声波衰减和频散比经典Biot模型可更好地解释实测结果。井孔声场模拟结果指出:在用单极子源声波测井数据进行渗透率反演时需要采用较低的声源频率,且需考虑地层局部渗流对井孔声波幅值的影响。

The acoustic field of acoustic logging is affected by reservoir permeability.Therefore,acoustic logging can be applied to reservoir permeability evaluation.However,the classical Biot poroelastic model,which describes the wave propagation in porous media,obviously underestimates the attenuation of waves in rocks.In order to solve the problem and apply acoustic logging to permeability evaluation,the study modifies the classical model by introducing the influence of local seepage on wave attenuation.Then,the modified model is used to simulate the borehole acoustic field and analyze the feasibility of inversion of reservoir permeability via acoustic logging data.The results show that the attenuation and dispersion calculated by modified model can better explain the measured ones.It is obtained from the borehole acoustic field modeling that when monopole acoustic well logging data is used for permeability inversion,a lower sound source frequency is needed and the influence of local seepage on the amplitude of borehole acoustic field need to be considered.