System and methodology for removing noise associated with sonic logging
AssigneeSchlumberger Technology Corporation
InventorsToshimichi Wago, Toshihiro Kinoshita, Jahir Pabon, Wataru Izuhara
Life of this patent
Estimating the term…
Abstract
A technique facilitates removal of noise from sonic logging signals. The technique may comprise various approaches used alone or in combination to reduce or eliminate noise associated with tool arrival. The technique may comprise an active cancellation approach which optimizes the cancellation effect while having minimal impact on the desired acoustic signals. The techniques also may utilize an asynchronous noise cancellation approach with a calibration transmitter designed to minimize impact on the desired acoustic signals.
Claims20
A method for evaluating a reservoir, comprising:
- deploying a sonic logging tool downhole into a borehole;
- operating the sonic logging tool to emit and receive acoustic signals from a main transmitter and a cancelling or calibration transmitter;
- processing received acoustic signals from the main transmitter and the cancelling or calibration transmitter facilitating removal of tool arrival.
A cancelling transmitter comprising:
- a plurality of piezo discs provided in a fluid filled cavity;
- wherein the plurality of piezo discs are axially aligned and polarized.
A system to analyze downhole entities, comprising:
- a sonic logging tool having:
- a tool body;
- a plurality of velocity sensors coupled to the tool body and decoupled from a surrounding fluid;
- a plurality of acoustic receivers;
- and
- a main transmitter to emit an acoustic wave to excite the formation;
- a cancellation or calibration transmitter to emit an axial wave to excite the tool body;
- a processor system receiving data from the plurality of velocity sensors and the plurality of acoustic receivers after the main transmitter emits the acoustic wave and the cancellation or calibration transmitter emits the axial wave, the processor system utilizing the data to facilitate removal of tool arrival from the data in order to analyze the downhole entities.
Dependencies are inferred from the claim text.