Method and apparatus for echo-peak detection for circumferential borehole image logging

摘要

Signals from an acoustic transducer used in a borehole include overlapping, ringing reflections from the casing walls, voids in the cement and the formation. By using the Hilbert transform, an envelope of the signals is determined and individual echoes are detected by using a Gauss-Laplace operator.

主权项

1. A method of characterizing cement in proximity to a casing installed in a borehole in an earth formation, the method comprising:
activating a transducer at at least one azimuthal orientation in the borehole and generating an acoustic pulse; receiving a signal comprising a plurality of overlapping events resulting from the generation of the acoustic pulse, at least one of the plurality of overlapping events being due to a ringing of the transducer; estimating an envelope of the received signal; and estimating from the envelope of the received signal an arrival time of each of the plurality of events by, at least in part, applying a Gaussian Laplace operator to the envelope to estimate arrival times, the arrival times being characteristic of a property of the cement in proximity to the casing, the property being an acoustic impedance of the cement in proximity to the casing.