裸眼井和套管井中偶极声场的辐射和接收

运用弹性波互易原理,指出并验证井中声场辐射和接收存在的互易性,使得井的接收响应可以由井的辐射因子计算得到,并结合辐射声场的远场渐近解,使得远探测声场的计算效率显著提高;模拟结果与三维有限差分数值模拟结果吻合。由于井对声场辐射和接收的调制作用,偶极横波远探测测井数据SH型横波的贡献远大于SV型横波的贡献,这一结果为数据的处理和解释提供了理论基础;模拟数据及其成像处理结果还证明了横波远探测技术在套管井中的可行性。所提的理论和方法可以快速模拟偶极横波远探测声场。

Radiation and reception of elastic waves from a dipole source in open and cased boreholes

According to elastic reciprocity theorem, the shear-wave radiation from a borehole dipole source is reciprocal to the reception in the source orientation of the borehole fluid displacement caused by the incidence of plane shear waves upon the borehole. Consequently, the borehole radiation pattern can be utilized to compute the borehole reception directivity. The results show that the radiation away from borehole can be accurately computed using an asymptotic solution in the far-field of the borehole. The use of the reciprocity theorem and the asymptotic solution greatly reduces the computational effort in the reflection survey simulation. The simulation results agree well with those from a 3D finite difference elastic wave simulation. The modeling results also show that the SH-wave component from the dipole source is a dominate component for the dipole shear-wave imaging. Simulation and processing results of cased-hole dipole reflection survey data also demonstrate the feasibility of applying the borehole shear-wave imaging technology in cased boreholes. The results of this work provide a fast and accurate algorithm for simulating the dipole-shear wave reflection survey along a borehole.