System and method for sonic wave measurements using an acoustic beam source

Patent metadata

Field	Value
Publication number	US-9103944-B2
Application number	US-201313836611-A
Country	US
Kind code	B2
Filing date	Mar 15, 2013
Priority date	Aug 21, 2012
Publication date	Aug 11, 2015
Grant date	Aug 11, 2015

Abstract

A method and system for investigating structure near a borehole are described herein. The method includes generating an acoustic beam by an acoustic source; directing at one or more azimuthal angles the acoustic beam towards a selected location in a vicinity of a borehole; receiving at one or more receivers an acoustic signal, the acoustic signal originating from a reflection or a refraction of the acoustic wave by a material at the selected location; and analyzing the received acoustic signal to characterize features of the material around the borehole.

First claim

What is claimed is:

1. A method for investigating cement bonding or rock formation structure near a borehole, comprising:
generating a collimated acoustic beam by an acoustic beam source, the collimated acoustic beam having a frequency in the frequency range between approximately 15 kHz and 120 kHz;
directing at one or more azimuthal angles and at one or more inclination angles the collimated acoustic beam towards a selected location in a vicinity of a borehole;
receiving, at an acoustic detector comprising a two-dimensional array of receiver elements, an acoustic signal, the acoustic signal originating from a reflection, a refraction, or a surface wave propagation, or any combination thereof, of the collimated acoustic beam by a material at the selected location in an azimuthal angular range, each receiver element in the two-dimensional array of receiver elements being configured to receive a portion of the acoustic signal corresponding to a portion of the azimuthal angular range, the two-dimensional array of receiver elements being disposed on a surface of a cylindrical member and being spaced apart to provide a gap between neighboring receiver elements, the two-dimensional array of receiver elements comprising a piezo-electric film;
analyzing the received acoustic signal to characterize features of the material around the borehole.

2. The method according to claim 1 , wherein generating the acoustic wave comprises transmitting a first acoustic wave and a second acoustic wave into an acoustically non-linear medium to produce a collimated beam by a non-linear mixing process, wherein the collimated beam propagates through the non-linear medium in a same direction as an initial direction of the first and second acoustic waves and has a frequency equal to a difference of the first and the second acoustic waves.

3. The method according to claim 2 , wherein the non-linear medium includes one or more of a mixture of liquids, a solid, a granular material, embedded microspheres, or an emulsion.

4. The method according to claim 2 , further comprising encoding the collimated beam with a time-varying code by introducing a time-varying component including one or more of chirping or frequency sweep to one of the first and the second acoustic signals.

5. The method according to claim 4 , wherein the time-varying components comprises a variation in amplitude, frequency, or phase, or any combination thereof.

6. The method according to claim 5 , wherein the time-varying components comprise a variation in amplitude, frequency, or phase, or any combination thereof.

7. The method according to claim 1 , wherein generating the acoustic wave comprises generating the acoustic wave using a plurality of transducers arranged in an array.

8. The method according to claim 1 , wherein directing the acoustic wave comprises directing the acoustic wave using a steering guide device.

9. The method according to claim 8 , wherein directing the acoustic wave comprises using a focusing device including an acoustic reflector, an acoustic lens or both.

10. The method according to claim 1 , wherein the analyzing comprises analyzing the received acoustic signal after it has reflected or backscattered from inhomogeneities in the rock formation or materials surrounding the borehole, or both to generate an image that provide information on cement bonding, fractured areas, or other defects.

11. The method according to claim 1 , further comprising moving the acoustic source and the one or more receivers as whole along a borehole axis.

12. The method according to claim 1 , further comprising moving the one or more receiver elements independently from the acoustic source along a borehole axis.

13. The method according to claim 1 , further comprising spacing the receiver elements in the array of receiver elements and selecting a size of the receiver elements to achieve a desired azimuthal angular resolution of the received acoustic signal between about 5 deg. and about 15 deg.

14. The method according to claim 1 , further comprising electronically selecting one or more receiver elements in the two-dimensional array of receiver elements to receive the acoustic signal without rotating the array of receiver elements.

15. The method according to claim 1 , wherein the piezo-electric film comprises a polyvinylidene difluoride (PVDF).

16. The method according to claim 1 , further comprising disposing the acoustic source and the one or more receiver elements within a housing and disposing the housing within a borehole.

17. The method according to claim 1 , further comprising moving the acoustic source independently from the one or more receivers.

18. The method according to claim 1 , further comprising rotating the acoustic source, the one or more receiver or both azimuthally around a borehole axis.

19. The method according to claim 1 , wherein characterizing features of the material around the borehole comprises detecting a fracture of in a cement casing of the borehole, a gap between the cement casing and the rock formation, or a gap between the cement casing and a metal casing of the borehole, or any combination thereof with an azimuthal resolution between approximately 5 deg. and approximately 15 deg.

20. The method according to claim 1 , wherein characterizing features of the material around the borehole comprises imaging reservoir layers, stratigraphy, fractures or faults, or any combination thereof with an azimuthal resolution between about 5 deg. and about 15 deg.

21. The method according to claim 1 , wherein characterizing features of the material around the borehole comprises measuring compressional velocity, shear velocity of the rock formation, or both with azimuth determination.

22. The method according to claim 21 , wherein characterizing features of the material around the borehole comprises detecting heterogeneities behind pipes or canalizations.

23. The method according to claim 1 , wherein the characterizing comprises performing 3D analysis of geo-mechanical properties around boreholes from analysis of refraction waves and Lamb waves to improve characterization of the invasion zone and any borehole damage.

24. The method according to claim 1 , wherein the characterizing comprises performing 3D imaging of velocity of rock formation near the borehole using refraction analysis.

25. The method according to claim 1 , wherein the characterizing comprises performing 3D mapping of fractures from reflections of linear arrivals.

26. The method according to claim 1 , wherein the characterizing comprises performing 3D mapping of permeability and production skin of reservoirs.

27. The method according to claim 1 , wherein generating an acoustic wave comprises generating an acoustic beam with a phase-code Gaussian pulses in the lower frequency range between approximately 10 kHz and about 30 kHz for deeper penetration into the rock formation.

28. The method according to claim 1 , wherein analyzing the received acoustic signal to characterize features of the material around the borehole comprises performing a time-frequency analysis of the received acoustic signal.

29. The method according to claim 28 , further comprising determining a frequency content of the received acoustic signal as a function of time so as to determine frequencies that are prominent at certain times during propagation.

Assignees

• Vu Cung Khac
• Sinha Dipen N
• Pantea Cristian
• Los Alamos Nat Security Llc
• Chevron Usa Inc

Inventors

• Vu Cung Khac
• Sinha Dipen N
• Pantea Cristian

Classifications

• G01V1/42

  using generators in one well and receivers elsewhere or vice versa (G01V1/52 takes precedence) · CPC title

• H04R17/00

  Piezoelectric transducers; Electrostrictive transducers (piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners {H10N30/00}) · CPC title

• G01V1/50 Primary

  Analysing data · CPC title

• B06B1/0688

  with foil-type piezoelectric elements, e.g. PVDF · CPC title

• G01V1/40

  specially adapted for well-logging · CPC title