Device and method for generating a beam of acoustic energy from a borehole, and applications thereof
View Patent ↗In some aspects of the invention, a method of generating a beam of acoustic energy in a borehole is disclosed. The method includes generating a first acoustic wave at a first frequency; generating a second acoustic wave at a second frequency different than the first frequency, wherein the first acoustic wave and second acoustic wave are generated by at least one transducer carried by a tool located within the borehole; transmitting the first and the second acoustic waves into an acoustically non-linear medium, wherein the composition of the non-linear medium produces a collimated beam by a non-linear mixing of the first and second acoustic waves, wherein the collimated beam has a frequency based upon a difference between the first frequency range and the second frequency, and wherein the non-linear medium has a velocity of sound between 100 m/s and 800 m/s.
1. A method of generating a collimated beam of acoustic energy within a logging tool and directing it into a borehole, the method comprising:
generating a first acoustic wave at a first frequency;
generating a second acoustic wave at a second frequency different from the first frequency, wherein the first acoustic wave and second acoustic wave are generated by at least one transducer carried by a tool located within the borehole;
transmitting the first and the second acoustic waves into an acoustically non-linear medium within the logging tool, wherein the composition of the non-linear medium produces a collimated beam by a non-linear mixing of the first and second acoustic waves, wherein the collimated beam has a frequency based upon a difference between the first frequency range and the second frequency, and wherein the non-linear medium has a sound velocity between 100 m/s and 800 m/s.
2. The method in accordance with claim 1 , wherein the non-linear medium has a nonlinearity parameter beta between 2 and 50.
3. The method in accordance with claim 1 , wherein the non-linear medium has a quality factor Q greater than 30.
4. The method in accordance with claim 1 , wherein the non-linear medium is selected from the group consisting of: a mixture of liquids, a solid, a granular material, embedded microspheres, an emulsion, and combinations thereof.
5. The method in accordance with claim 1 , wherein the collimated beam has a frequency range.
6. The method in accordance with claim 5 , wherein the frequency range of the collimated beam is between 15 kHz and 120 kHz.
7. The method in accordance with claim 1 , wherein the first frequency comprises a range of frequencies.
8. The method in accordance with claim 1 , wherein the second frequency comprises a range of frequencies.
9. The method in accordance with claim 1 , further comprising transmitting the collimated beam into a material around the borehole.
10. The method in accordance with claim 9 , wherein the material is rock formation, cement, or casing, or a combination thereof.
11. The method in accordance with claim 9 , further comprising reflecting and guiding the collimated acoustic beam by a movable acoustic mirror.
12. A wireline or pipe conveyed logging tool deployed within a borehole, configured to generate and direct a collimated acoustic beam within the tool, the tool comprising:
a housing;
at least one transducer, carried by the housing, and configured to produce a first acoustic wave at a first frequency and a second acoustic wave at a second frequency different from the first frequency; and
a non-linear medium carried by the housing, wherein the composition of the non-linear medium is configured to produce a collimated beam by a non-linear mixing of the first and second acoustic waves, wherein the collimated beam has a frequency based upon a difference between the first frequency and the second frequency, and wherein the non-linear medium has a velocity of sound between 100 m/s and 800 m/s.
13. The tool in accordance with claim 12 , wherein the non-linear medium has a nonlinearity parameter beta between 2 and 50.
14. The tool in accordance with claim 12 , wherein the non-linear medium has a quality factor Q greater than 30.
15. The tool in accordance with claim 12 , wherein the non-linear medium is selected from the group consisting of: a mixture of liquids, a solid, a granular material, embedded microspheres, an emulsion, and a combination thereof.
16. The tool in accordance with claim 12 , wherein the collimated beam has a frequency range.
17. The tool in accordance with claim 12 , wherein the frequency range of the collimated beam is between 15 kHz and 120 kHz.
18. The tool in accordance with claim 12 , wherein the first frequency comprises a range of frequencies.
19. The tool in accordance with claim 12 , wherein the second frequency comprises a range of frequencies.
20. The tool in accordance with claim 12 , wherein the tool is configured to transmit the collimated beam into a material around the borehole.
21. The tool in accordance with claim 20 , wherein the material is rock formation, cement, or casing, or a combination thereof.
22. The tool in accordance with claim 12 , further comprising a movable acoustic mirror configured to reflect and guide the collimated acoustic beam.