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在做横波勘探时,若不考虑方位各向异性的影响,就不能取得精确的结果。为了勘查裂隙,可以直接利用各向异性测量资料推断出裂隙的存在及其方位。然而,在应用横波勘探进行成像及AVO研究时,必须考虑各向异性引起的数据失真。因此,测量出研究区目的层的横波各向异性的量级、方位及随深度的变化是非常必要的。 文中用三种不同的算法研究了合成和实际数据集。这两种数据集都含有正交偏振产生的直达横波及地表纵波震源产生的转换横波。 算法是:包括剥层处理在内的四分量旋转法,它只能用于正交横波震源数据;互相关预测模拟法以及参数反演法。这些算法已用于直达横波以及地下模型转换所产生的横波。后两种算法还可用于单个震源产生的单相偏振的数据。 当这三种算法用于合成数据时,都可获得类似的结果。三种算法用于实际数据所获得的结果也基本相似。只是由于数据特征不同具有不同的灵敏度。实际转换波数据的分析结果是令人满意的,因为这些数据的频带比地表产生的数据的频带更宽。纵波震源的偏移距非常小,在2100米的井中为300米,因而转换横波传播路径是近于垂直的,这就避免了横向各向同性介质产生的各向异性效应的干扰。 实际数据分析表明,井底存在双折射的某些证据(可能达5％的各向异性),各向异性层与各向同性层呈
When doing transverse wave surveys, accurate results can not be obtained without considering the effects of azimuthal anisotropy. In order to investigate fissures, anisotropy measurements can be used directly to infer the existence and orientation of fissures. However, anisotropy-induced data distortion must be considered when applying shear wave exploration for imaging and AVO studies. Therefore, it is necessary to measure the magnitude, azimuth and the variation with depth of shear-wave anisotropy in the target layer of the study area. In this paper, three different algorithms are used to study the synthesis and actual data sets. Both datasets contain transversal shear waves produced by orthogonal polarizations of the transversal and terrestrial sources. The algorithm is: a four-component rotation method including delamination processing, which can only be used for orthogonal S-wave source data; cross-correlation prediction simulation method and parameter inversion method. These algorithms have been applied to shear waves generated by the direct shear wave and the underground model transformation. The latter two algorithms can also be used for single-phase polarization generated data from a single source. Similar results are obtained when the three algorithms are used to synthesize the data. The results obtained by the three algorithms for the actual data are also basically similar. Just because of different data features have different sensitivities. The results of the analysis of the actual converted wave data are satisfactory because the band of these data is wider than the band of data of the surface. Polarimeters have very small offsets, 300 m at 2,100 m, so that the transversal shear wave propagation path is near vertical, which avoids the interference of anisotropic effects from transversely isotropic media. The actual data analysis shows that there is some evidence of birefringence (up to 5% anisotropy) at the bottom of the well, with anisotropy and isotropy