Simultaneous digitizing apparatus for an acoustic tool

Claim 1

For use in a well borehole to obtain multiple simultaneous data signals from N acoustic receivers carried by an elongated acoustic logging sonde sized and adapted for passage in the well borehole and suspended by a well logging cable having a single acoustic data conductor, the multiple simultaneous signals formed in response to a single acoustic energy pulse from an acoustic transmitter carried by the sonde, a data collection system comprising: (a) N acoustic receivers supported by an acoustic logging sonde forming N time overlapping acoustic logging output signals from the receivers where N is an integer; (b) first multiplexing means having N inputs connected to the outputs of said N acoustic receivers; (c) second multiplexing means connected to said first multiplexing means; (d) digital converter means operating at a first rate and connected to said second multiplexing means for forming a time based series of digital words representative of the output signals of said N receivers; (e) digital data buffer means in said sonde and connected to said digital converter means for recording in a formatted order a series of digital words from said converter means; (f) an acoustic transmitter monitor means for monitoring acoustic transmitter pulses transmitted by the acoustic transmitter and supplying the monitored transmitter pulses to said second multiplexing means; (g) control means connected to said first and second multiplexing means for controlling operation of said first and second multiplexing means to form a series of digital words representative of; (1) the monitored transmitter pulses from said acoustic transmitter monitor, and (2) the N acoustic logging output signals; (h) timing means incorporated with said control means to time digitizing by said digital converter means to operate both said first and second multiplexing means to form: (1) a first series of digital words representing the monitored transmitter pulses; and (2) a second and later series of digital words representing the N acoustic logging output signals; and (i) telemetry transmitting means for telemetering the first and second series of digital words from said buffer means along the single acoustic data conductor in the cable at a second rate which rate is less than the first rate such that a single acoustic energy pulse from said acoustic transmitter generates N digital representations of the acoustic energy received at said N acoustic receivers corresponding to the arrival at each receiver of a single acoustic energy pulse.

Claim 7

A method of acoustic logging in a well borehole below a surface with an acoustic pulse transmitter on a sonde supported by a cable wherein the cable has a single acoustic data signal conductor and N multiple acoustic receivers on the sonde to observe overlapping received acoustic signals, the method comprising the steps of: (a) transmitting an acoustic pulse by a transmitter; (b) forming a signal by monitoring the acoustic pulse transmitter during operation thereof ; (c) multiplexing and digitizing the formed signal for a first time interval beginning at time equals zero to form a series of digital words representing the acoustic pulse; (d) storing the digital words in a memory in the sonde; (e) listening for overlapping acoustic signals resulting from the transmitted acoustic pulse at N acoustic receivers along the well borehole and forming an analog signal from each of the N receivers; (f) multiplexing the overlapping N received analog signals at first and second rates; (g) digitizing the multiplexed N analog signals into a series of digital words encoding the N analog signals; (h) storing the digital words encoding the N analog signals in a specified sequence in the memory; and (i) telemetering from the sonde along the single acoustic data signal conductor along the cable supporting the sonde to the surface digital words in the memory representing the monitored acoustic transmitter pulse and the N received signals, wherein the telemetering rate is slower than the first rate.

Claim 8

A method of acoustic logging in a well borehole below a surface with an acoustic pulse transmitter on a sonde supported by a cable wherein the cable has a single acoustic data signal conductor and N multiple acoustic receivers on the sonde to observe overlapping received acoustic signals, the method comprising the steps of: (a) transmitting an acoustic pulse by a transmitter; (b) forming a signal by monitoring the acoustic pulse transmitter during operation thereof ; (c) multiplexing and digitizing the formed signal for a first time interval beginning at time equals zero to form a series of digital words representing the acoustic pulse; (d) storing the digital words in a memory in the sonde; (e) listening for overlapping acoustic signals resulting from the transmitted acoustic pulse at N acoustic receivers along the well borehole and forming an analog signal from each of the N receivers; (f) multiplexing the overlapping N received analog signals at first and second rates; (g) digitizing the multiplexed N analog signals into a series of digital words encoding the N analog signals; (h) storing the digital words encoding the N analog signals in a specified sequence in the memory; and (i) telemetering from the sonde along the single acoustic data signal conductor along the cable supporting the sonde to the surface digital words in the memory representing the monitored acoustic transmitter pulse and the N received signals, wherein the telemetering rate is slower than the first rate.