正交偶极声波测井资料在评价地层各向异性中的应用

Evaluating formation shear-wave anisotropy by using cross-dipole acoustic logging data

1. 石油大学(华东)地球资源与信息学院,山东东营 257061;2. 石油大学(北京)地球资源与信息学院,北京 102249

College of Geo-resources and Information, China University of Petroleum, Dongying 257061, China

裂缝和不均衡地应力等均可引起地层的各向异性,利用正交偶极子测量的4组波形可在井孔内评价地层的各向异性。其方法原理是,根据各向异性地层中偶极声源激发的快、慢弯曲波具有波形相似的特征,对所有接收阵列的快、慢弯曲波进行波形匹配,并构造目标函数,然后反演出地层的各向异性参数。用该方法处理了裂缝性和存在不均衡地应力地层中多口井的正交偶极资料,处理结果与成像资料基本吻合,表明各向异性系数和快横波方位能够用来指示地层的裂缝和地应力信息。

Both fracture and stress difference can induce formation shear-wave anisotropy that can be measured by four component waveforms of the cross-dipole logging in filled-fluid borehole. In anisotropic formation, the waveform of fast flexural wave is similar to that of slow flexural wave. Based on the above characteristic of fast and slow flexural waves, their waveforms of all receives are matched, an objective function is constructed, and the formation shear-wave anisotropy parameters are inverted quickly and accurately. The method is used to process field cross-dipole logging data in fractured and unbalanced stress formations respectively. The results obtained accord with the imaging data, which shows that the information of fracture and formation stress can be indicated by the anisotropy coefficient and fast shear azimuth.