利用井中偶极声源远场辐射特性的远探测测井

远探测声波测井技术近年来的一个重要进展是利用偶极声波探测仪器来发射和接收地层深部的反射信号.本文论述了这种偶极声波远探测技术的基本原理和方法,并结合数值模拟计算验证了该方法的可行性及灵敏度.具体来说,井中偶极声源向地层深部辐射出纵波、SH和SV型横波,其中SH型横波具有很宽的辐射覆盖及较高的反射灵敏度,是偶极横波远探测...

Single-well acoustic reflection imaging using far-field radiation characteristics of a borehole dipole source

An important recent advance in single-well reflection imaging is the utilization of a dipole acoustic system in a borehole to radiate and receive elastic waves to and from a remote geologic reflector in formation. This paper elaborates the fundamental theory and method of the dipole acoustic imaging technology, analyzing its sensitivity and feasibility in conjunction with a numerical modeling study. The analyses show that a borehole dipole source can radiate a compressional (P) wave and two types of shear wave (i.e., SV and SH waves) into the formation. The SH wave has wide radiation coverage and best reflection sensitivity, providing the foundation for dipole-shear imaging. In an acoustically slow formation, the dipole-generated P wave has strong reflection sensitivity and can also be utilized for reflection imaging. An important feature of dipole imaging is its sensitivity to reflector azimuth, which results from the directivity of the dipole source. By using a four-component data acquisition method to record the dipole-generated reflection signal, the reflector azimuth can be determined. Field data examples are used to demonstrate the characteristics of dipole acoustic imaging and its effectiveness.