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横波双折射总是与垂直裂隙的存在相联系的。在这种情况下,识别裂隙的常规方法是探测横波VSP中的横波分裂。这些勘查将海洋采集排除在外且局限于能用横波震源的地区。本文描述了一种用有井源距VSP的转换横波测量横波双折射的技术。假定SV波的传播是几乎垂直的,参数反演方法可被应用到根据三个参数:快横波偏振和快、慢横波速度模拟的多分量有井源距VSP数据的水平分量中。本技术可应用于来自裂隙区之上的SV波和双折射层顶端产生的波型转换横波中。在这种情况下,分别地处理SV波能提供有意义区域中存在横波双折射的证据。
Skew birefringence is always associated with the existence of vertical fractures. In this case, the conventional method of identifying a fracture is to detect shear-wave splitting in the shear-wave VSP. These surveys exclude marine acquisitions and are limited to areas where shear waves can be sourced. This paper describes a technique for measuring transverse birefringence using a converted shear wave with a well-to-source distance VSP. Assuming that SV-wave propagation is almost vertical, the parametric inversion method can be applied to the horizontal component of the multi-component well-to-ground distance VSP data according to three parameters: fast-wave polarization and fast and slow shear-wave velocity simulations. The present technique can be applied to wave-transformed shear waves generated from SV waves and birefringent layers atop crevice regions. In this case, separately processing the SV wave energy provides evidence of the presence of shear-wave birefringence in the region of interest.