储层砂岩的各向异性

Anisotropy in reservoir sandstone

对泵油饱和南京砂岩施以正弦波载荷来模拟地震波在储层砂岩中的传播，进而研究地震波的频率和振幅对储层砂岩的衰减、杨氏模量、油松比、纵横波速度和各向异性的影响。获得了以下结论：①随正弦波频率的增高，杨氏模量、泊松比、纵横波速度都增大；频率越高，增长速率越快、频散效应越显著。②当固定频率，不断增大应变振幅时，其衰减增大，而杨氏模量和泊松比及纵横波速度却反而降低。③无论是随频率的增高，或应变振幅的增大，上述物理力学参数及动力学参数都存在极为明显的各向异性；这种各向异性既与南京砂岩固有的各向异性有关，也与饱和流体沿施加压力方向的流动和扩散有关；这种压力引起的非破坏性小变形，将导致储层的各向异性。

Effect of seismic frequency and amplitude on attenuation, Young's modules, Poisson's ration, compressional wave and shear wave velocity and anisotropy has been studied when loading sine-wave on pumped oil-saturated Nanjing sandstone to model seismic propagation in reservoir sandstone. The obtained results are follows: ①Young's modulus,Poisson's ration and compressional wave and shear wave velocity increase with increasing frequency of sine-wave and the higher frequency is, the faster increasing rate is and the more obvious dispersion effect is; ②attenua tion increases with increasing strain amplitude while Young's modulus, Poisson's ration and compressional wave and shear wave velocity instead when fixed frequency; ③obvious anisotropy exists in above mentioned physico-mechanic and dynamic parameters whether frequency increased or strain amplitude increased. These anisotropy related both with intrinsic anisotropy of sandstone and with that saturated fluid flows and disperses along the direction that pressure was loaded on, as the pressure caused small non-destructive deformation, so it resulted reservoir anisotropy.