Patent ID: 6014609
Filing Date: 2000-01-11
Classification: G01V

Abstract:
A method for collecting acoustic data produced in response to the transmission of an acoustic pulse down a borehole in the earth, comprising the steps of:monitoring the acoustic environment within said borehole to produce a detection signal,applying a variable gain to said detection signal to produce an output signal,prior to the generation of said acoustic pulse, monitoring background noise in said borehole as said detection signal and selecting a first gain value for application to said detection signal to produce said output signal to have a first predetermined amplitude,detecting the occurrence of said acoustic pulse in said detection signal, andafter detecting said occurrence of said acoustic pulse, increasing the gain applied to said detection signal when an amplitude related to a preceding portion of said output signal is less than a first limit, and decreasing the gain applied to said detection signal when an amplitude related to a preceding portion of said output signal is more than a second limit, but limiting the gain applied to said detection signal to not exceed said first gain value.