| 摘要 |
An acoustic well logging method employing a tool having at least two acoustic transmitters and at least two acoustic receivers. In a preferred embodiment, one receiver is positioned midway between the two transmitters, and the other receiver is spaced from the first receiver along the longitudinal axis of the tool between the transmitters. Two signals, each representing an acoustic wave that has propagated from a transmitter through a portion of the formation surrounding the borehole to a receiver, are recorded when the tool is in each of two positions relative to the longitudinal axis of the well. In each of the tool positions, one recorded signal is associated with the midpoint receiver and the other with another receiver. From the four recorded signals, a new signal is generated. This derived signal has Fourier amplitude spectrum indicative of the formation parameters, but is independent of components associated with the transmitters and receivers. Thus the method results in amplitude information that is neither corrupted by variations in the sensitivity between the various receivers and transmitters, nor by variations in sensitivity of any individual transducer over time. In an alternative preferred embodiment, the positions of the transmitters and receivers in the tool are interchanged. In variations on the preferred embodiments, three or more pairs of recorded signals are generated.
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