Method and apparatus for beam steering and bessel shading of conformal array

• US 5,640,371 A
• Filed: 11/22/1995
• Issued: 06/17/1997
• Est. Priority Date: 03/22/1994
• Status: Expired due to Term

• Current Assignee: Western Atlas International Incorporated (Northrop Grumman Corporation)
• Original Assignee: Western Atlas International Incorporated (Northrop Grumman Corporation)
• Inventors: Priest, John F., Schmidt, Mathew G.
• Primary Examiner(s): Pihulic, Daniel T.
• Application Number:
  US08/562,299
• Time in Patent Office: 573 Days
• Field of Search: 367/912, 367/911, 367/153, 367/162, 367/176, 367/152, 367/25, 367/180, 73/626, 310/326, 310/327, 310/334, 181/104
• US Class Current: 367/153
• CPC Class Codes: B06B 1/0633 Cylindrical array
• CPC Class Codes: G01S 15/892 the array being curvilinear
• CPC Class Codes: G01S 15/8925 the array being a two-dimensional transducer configuration, i.e. matrix or orthogonal linear arrays
• CPC Class Codes: G01V 1/52 Structural details
• CPC Class Codes: G10K 11/26 Sound-focusing or directing, e.g. scanning
• CPC Class Codes: Y10S 367/912 Particular transducer

Abstract

This invention describes a methodology to image features using an array of multiple piezo-electric elements which employs the selective use of mechanical and electronic beam focusing, electronic beam steering and amplitude shading to increase resolution and overcome side lobe effects. This invention introduces a novel signal reconstruction technique utilizing independent array element transmission and reception, creating focusing and beam steering. Application of the methodology can be used in wireline, measurement while drilling, pipe and pipeline and medical applications. Applications include, but are not limited to Bore hole Caliper, Bore hole Geometry, Bore hole Imaging, Casing Inspection, Cement Evaluation and Volumetric Scanning Applications (e.g. Fluid, Behind Casing and Open Hole). The configuration of the transducer array is preferably cylindrical, but may be conical, biconical, convex, concave or may take the form of a number of suitable geometric configurations. The transducer array may incorporate a transformer block having an array of multiple transformers therein for connection to individual transducer circuits. The transformers may be fixed or capable of being mechanically tuned as desired.

Claims

1. An acoustic sonde for down hole well logging operations, comprising:

(a) housing means defining an internal chamber and having an acoustically transparent housing section;

(b) an annular acoustic transmitter array located within said housing means adjacent said acoustically transparent section and comprising;

(1) an annular backing element composed of acoustically attenuating material;

(2) a plurality of acoustic transducer elements each being located externally of said annular backing element;

(3) a plurality of electronic transducer circuits;

(4) a generally circular ferrite array transformer block having a plurality of transformers mounted therein, each being individually electrically interconnected between said electronic transducer circuits and said individual transducer elements for electronic excitation thereof, the transformer block further including means for inductively tuning at least some of said transformers; and

(c) electronic transmitting/receiving circuitry being coupled in controlling relation with said plurality of electronic transducer circuits.

2. The acoustic sonde of claim 1, further comprising:

a body of high structural strength, acoustically transparent material having said plurality of spaced acoustic transducer elements embedded therein.

3. The acoustic sonde of claim 1, further comprising:

transducer body means securing said plurality of acoustic transducer elements in spaced relation with one another, said transducer body means having a substantially equal coefficient of expansion as compared with the coefficient of expansion of said acoustic transducer elements.

4. The acoustic sonde of claim 1, further comprising:

(a) said transducer array having an array mounting defining a window surface and being composed of a material that is acoustically transparent at said window surface;

(b) said plurality of acoustic transducer elements being supported by said array mounting and being oriented to project acoustic waves through said window surface.

5. The acoustic sonde of claim 4, wherein:

said array mounting is composed of carbon composite material and arranged to resist the radially compressive forces of hydrostatic pressure.

6. The acoustic sonde of claim 1, wherein:

said plurality of acoustic transducer elements define a vertically focused horizontal scanning array arranged for incidence on the wall of said bore hole at a predetermined angle.

7. The acoustic sonde of claim 6, wherein:

said predetermined angle is in the range from about 10°

to about 35° and

preferably about 20°

.

8. The acoustic sonde of claim 6, wherein:

said vertically focused horizontal scanning array is of generally conical configuration.

9. The acoustic sonde of claim 1, wherein:

(a) said annular acoustic transducer array defines an array height; and

(b) each of said plurality of acoustic transducer elements being of generally rectilinear configuration and having a length substantially equal to said array height.

10. The acoustic sonde of claim 1, wherein said acoustic transducer array comprises:

a plurality of equal width generally rectilinear acoustic transducer elements arranged in equally spaced relation and collectively defining a generally cylindrical transducer array.

11. The acoustic sonde of claim 1, wherein said transducer array is of generally cylindrical configuration having an array height and having a cylindrical axis and further comprising:

a set of acoustic transducer elements having a plurality of rectilinear acoustic transducer elements each having equal width and being of array height and being oriented in equally spaced relation about said cylindrical axis.

12. The acoustic sonde of claim 11, wherein said transducer array further comprises:

a plurality of axially spaced sets of said generally rectilinear transducer elements with each of said axially spaced sets having a plurality of said acoustic transducer elements.

13. The acoustic sonde of claim 1, wherein said transducer array comprises:

a set of "N" equal width rectilinear acoustic transducer elements aligned along the cylindrical axis of the array and having a length equal to array height, where "N" is an arbitrary number of acoustic transducer elements.

14. The acoustic sonde of claim 1, wherein said acoustic transducer array comprises:

(a) a cylindrical axis being defined by said transducer array; and

(b) a set of "N" times "M" equal length and equal width generally rectilinear acoustic transducer elements aligned along the cylindrical axis of the array, where "N" is the number of transducer elements around the array and "M" is the number of transducer elements along the cylindrical axis of the array.

15. The acoustic sonde of claim 1, wherein said acoustic transducer array comprises:

(a) an axis being defined by said transducer array; and

(b) a set of "N" equal width curved acoustic transducer elements having a geometric radius "R" being parallel to said axis of said transducer array and creating a predetermined focal distance "F", said curved acoustic transducer elements being aligned along said axis and each having a length equal to the height of said transducer array.

16. The acoustic sonde of claim 1, wherein said acoustic transducer array defines a cylindrical axis and further comprises:

A set of "N" times "M" unequal size rectilinear acoustic transducer elements aligned along the cylindrical axis of the array, where "N" is the number of elements around the array, and "M" is the number of elements along the cylindrical axis of the array.

17. The acoustic sonde of claim 1, wherein said acoustic transducer array defines a cylindrical axis and further comprises:

a set of "N" times "M" unequal length and width curved acoustic transducer elements having a geometric radius "R" parallel to the axis of the array creating a focal distance "F", said curved acoustic transducer elements being aligned along the cylindrical axis of the array and having a length equal to array height.

18. The acoustic sonde of claim 1, wherein said acoustic transducer array defines a cylindrical axis and further comprises:

a set of "N" times "M" unequal length and width curved acoustic transducer elements having a geometric radius "R" parallel to the axis of the array defining a focal distance "F", said curved acoustic transducer elements being aligned along the cylindrical axis of the array and being mounted such that their surface lies on the geometric surface of radius "R", said curved acoustic transducer elements further having a collective length defining array height.

19. The acoustic sonde of claim 1, wherein said acoustic transducer array defines a cylindrical array axis and further comprises:

a set of "N" times "M" rectilinear acoustic transducer elements arranged such that the long dimension of each acoustic transducer element is oriented perpendicular to the array axis and where "N" is the number of acoustic transducer elements arranged around the array axis and "M" is the number of acoustic transducer elements along the array axis.

20. The acoustic sonde of claim 1, wherein said acoustic transducer array defines a cylindrical array axis and further comprises:

a set of "N" times "M" curved unequal length and width acoustic transducer elements arranged such that the long dimension thereof is oriented perpendicular to said array axis where "N" is the number of acoustic transducer elements arranged around the array axis and "M" is the number of acoustic transducer elements along the array axis and wherein the curvature of said acoustic transducer elements defines a physical focusing in the direction perpendicular to the array axis.

21. The acoustic sonde of claim 1, wherein said acoustic transducer array defines an array axis and a frustum of a cone described by a surface of revolution about the array axis described by a circle of a radius and where the radius is not perpendicular to the array axis.

22. The acoustic sonde of claim 21, wherein said acoustic transducer array comprises:

a set of "N" equal width rectilinear acoustic transducer elements oriented in aligned relation with said frustum of a cone and being aligned along said array axis and having a length defining the height of said array and where "N" is an arbitrary number of said acoustic transducer elements.

23. The acoustic sonde of claim 21, wherein said acoustic transducer array comprises:

a set of "N" times "M" equal length and width rectilinear acoustic transducer elements being oriented in aligned relation with said frustum of a cone and being aligned along the cylindrical axis of the array, where "N" is the number of acoustic transducer elements around the array and "M" is the number of acoustic transducer elements along the axis of said array.

24. The acoustic sonde of claim 21, wherein said acoustic transducer array comprises:

a set of "N" equal width curved acoustic transducer elements being oriented along the surface of said frustum of a cone and having a geometric radius "R" being parallel to the axis of the array and establishing a focal distance "F", said curved acoustic transducer elements being aligned along the axis of the array and having a length defining the height of said array.

25. The acoustic sonde of claim 21, wherein said acoustic transducer array comprises:

a set of "N" times "M" unequal size rectilinear acoustic transducer elements being oriented along the surface of said frustum of a cone and being aligned along the axis of the array and where "N" is the number of acoustic transducer elements around the array and "M" is the number of acoustic transducer elements located along the axis of the array.

26. The acoustic sonde of claim 21, wherein said acoustic transducer array comprises:

a set of "N" times "M" unequal length and width curved acoustic transducer elements having a geometric radius "R" being oriented in parallel relation with the axis of the array and establishing a focal length "F", said curved transducer elements being oriented along the surface of said frustum of a cone and further being aligned along the axis of the array, said curved transducer elements having a length defining the height of the array.

27. The acoustic sonde of claim 26, wherein:

said curved acoustic transducer elements are of trapezoidal configuration having widths that increase along the conic surface thus maintaining substantially equal spacing of said curved acoustic transducer elements along the lengths thereof.

28. The acoustic sonde of claim 21, wherein said acoustic transducer array comprises:

a set of "N" times "M" rectilinear acoustic transducer elements being oriented along the surface of said cone and being arranged such that the long dimension of each acoustic transducer element is located perpendicular to the array axis and where "N" is the number of acoustic transducer elements arranged around the array axis and "M" is the number of acoustic transducer elements located along the array axis.

29. The acoustic sonde of claim 21, wherein said acoustic transducer array comprises:

a set of "N" times "M" curved acoustic transducer elements having unequal length and width and being oriented along the surface of said cone and being arranged such that the long dimension thereof is located perpendicular to the array axis and where "N" is the number of acoustic transducer elements arranged around the array axis and "M" is the number of acoustic transducer elements located along the array axis, said curved acoustic transducer elements defining a physical focusing in the direction perpendicular to the array axis.

30. The acoustic some of claim 1, wherein said acoustic transducer array defines a generally cylindrical external configuration.

31. The acoustic some of claim 1, wherein said acoustic transducer array defines a generally frusto-conical external configuration.

32. The acoustic sonde of claim 1, wherein said acoustic transducer array defines a curved, concave external configuration having upper and lower ends having a selected diameter and an intermediate portion having a diameter less than said selected diameter.

33. The acoustic sonde of claim 1, wherein said acoustic transducer array defines a biconical external configuration having upper and lower array sections of generally frusto-conical configuration and arranged with the apexes thereof oriented toward one another.

34. The acoustic sonde of claim 1, wherein said acoustic transducer array defines a biconical external configuration having upper and lower array sections of generally frusto-conical configuration and arranged with the large dimensions thereof oriented toward one another and with the apexes thereof defining respective upper and lower ends of said acoustic transducer array.

35. The acoustic sonde of claim 1, wherein said acoustic transducer array defines upper and lower array sections each having a tapered, curved external configuration and defining ends of respective large and small dimension and being arranged with the small dimensions thereof oriented toward one another and with the large dimensions thereof defining respective upper and lower ends of said acoustic transducer array.

36. The acoustic sonde of claim 1, wherein said acoustic transducer array defines upper and lower array sections each having a tapered, curved external configuration and defining ends of respective large and small dimension and being arranged with the large dimensions thereof oriented toward one another and with the small dimensions thereof defining respective upper and lower ends of said acoustic transducer array.

37. The acoustic sonde of claim 1, wherein said acoustic array is mechanically focused.

38. The acoustic sonde of claim 37, wherein said acoustic array is mechanically focused in the axial direction.

39. The acoustic sonde of claim 37, wherein said acoustic array is mechanically focused in the orthogonal direction.

40. The acoustic sonde of claim 37, wherein said acoustic array is mechanically focused by the configuration and orientation of said acoustic transducer elements.

41. The acoustic sonde of claim 37, wherein said acoustic array is mechanically focused by acoustic lensing for all acoustic transducer elements of said array.

42. An acoustic transducer array, comprising:

(a) a plurality of acoustic transducer elements being disposed in substantially equally spaced electrically isolated relation and being arranged to define an acoustic transducer array of annular configuration;

(b) an acoustic attenuating backing of annular external configuration being located internally of said annular transducer array;

(c) electronic circuit means establishing electrical supply and return connections with said plurality of acoustic transducer elements and being selectively operative for individually controlled excitation of each said acoustic transducer elements of said acoustic transducer array;

(d) a ferrite transformer block including a plurality of transformers mounted therein, each said transformer being electrically interconnected between the respective electrical supply connections and corresponding acoustic transducer elements of said array, thereby to provide enhanced electronic excitation thereof; and

(e) means for mechanically tuning each said transformer.

43. The acoustic transducer array of claim 42, wherein:

said acoustic transducer array is of generally cylindrical configuration.

44. The acoustic transducer array of claim 42, wherein:

said acoustic transducer array is of generally conical configuration.

45. The acoustic transducer array of claim 42, wherein:

said acoustic transducer array comprises generally conical sections at each extremity and a generally cylindrical intermediate section.