Acoustic multi-mode logging device adapted to decouple noise within a semi-rigid receiver array

摘要

A multi-mode receiver sonde having individual receiver stations within a semi-rigid receiver array. The semi-rigid receiver array is adapted to decouple noise (tool-mode noise and/or road-noise) at one location within the receiver array from other locations within the receiver array by using compliant spacers between the receiver stations to absorb and scatter the noise. In preferred embodiments, multi-mode receiver stations are presented which provide a common ground for output signals detected by the receiver stations. Additional embodiments provide for combining the output signals into composite signals which represent a selected borehole propagation mode. In one highly preferred embodiment, the use of transducer detectors which have a flat frequency response over a selected bandwidth allows for accurate comparisons between composite signals so that changes in phase and amplitude over distance and time can be determined.