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 and the second frequency; and transmitting the collimated beam through a diverging acoustic lens to compensate for a refractive effect caused by the curvature of the borehole.
1. A method of generating a beam of acoustic energy in a borehole, the method comprising:
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 and the second frequency; and
transmitting the collimated beam through a diverging acoustic lens to compensate for a refraction effect caused by the curvature of the borehole.
2. The method in accordance with claim 1 , further comprising reflecting and guiding the collimated acoustic beam by a movable acoustic mirror.
3. 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 a combination thereof.
4. The method in accordance with claim 1 , wherein the collimated beam has a frequency range.
5. The method in accordance with claim 4 , wherein the frequency range of the collimated beam is between 15 kHz and 120 kHz.
6. The method in accordance with claim 1 , wherein the first acoustic wave has a range of frequencies.
7. The method in accordance with claim 1 , wherein the second acoustic wave has a range of frequencies.
8. The method in accordance with claim 1 , further comprising transmitting the collimated beam into a material around the borehole.
9. The method in accordance with claim 8 , wherein the material is rock formation, cement, or casing, or a combination thereof.
10. The method in accordance with claim 1 , wherein the diverging acoustic lens is a mirror.
11. The method in accordance with claim 1 , wherein the diverging acoustic lens is transmissive.
12. The method in accordance with claim 1 , further comprising transmitting the collimated beam through a second acoustic lens arranged along a transmission path that is between the diverging lens and the non-linear medium.
13. The method in accordance with claim 12 , wherein the second acoustic lens is a converging lens.
14. The method in accordance with claim 1 , wherein the non-linear medium has a velocity of sound between 100 m/s and 800 m/s.
15. A wireline or pipe conveyed logging tool positionable within a borehole, 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 than the first frequency;
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
a diverging acoustic lens configured to transmit the collimated beam and to compensate for a refraction effect caused by the curvature of the borehole.
16. The tool in accordance with claim 15 , further comprising an acoustic mirror configured to reflect and guide the collimated acoustic beam in a given direction.
17. The tool in accordance with claim 15 , 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.
18. The tool in accordance with claim 15 , wherein the collimated beam has a frequency range.
19. The tool in accordance with claim 18 , wherein the frequency range of the collimated beam is between 15 kHz and 120 kHz.
20. The tool in accordance with claim 15 , wherein the first acoustic wave has a range of frequencies.
21. The tool in accordance with claim 15 , wherein the second acoustic wave has a range of frequencies.
22. The tool in accordance with claim 15 , wherein the diverging acoustic lens is configured to transmit the collimated beam into a material around the borehole.
23. The tool in accordance with claim 22 , wherein the material is rock formation, cement, or casing, or a combination thereof.
24. The tool in accordance with claim 15 , wherein the diverging acoustic lens is a mirror.
25. The tool in accordance with claim 15 , wherein the diverging acoustic lens is transmissive.
26. The tool in accordance with claim 1 , further comprising a second acoustic lens configured arranged along a transmission path that is between the diverging lens and the non-linear medium.
27. The tool in accordance with claim 26 , wherein the second acoustic lens is a converging lens.
28. The tool in accordance with claim 15 , wherein the non-linear medium has a velocity of sound between 100 m/s and 800 m/s.