US3053338A

US3053338A - Acoustic transducers

Info

Publication number: US3053338A
Application number: US849891A
Authority: US
Inventors: Robert B Blizard
Original assignee: Schlumberger Well Surveying Corp
Current assignee: Schlumberger Well Surveying Corp
Priority date: 1959-10-30
Filing date: 1959-10-30
Publication date: 1962-09-11
Anticipated expiration: 1979-09-11

Description

Sept- 11, 1962 R. B. BLIZARD 3,053,338

ACOUSTIC TRANSDUCERS Filed Oct 30, 1959 4/ Robert .5. .B/IZCIIQ INVENTOR.

ATI'UR/VEF United States Patent 3,053,338 ACOUSTIC TRANSDUCERS Robert B. Blizard, Houston, Tex., assignor to Schlumberger Well Surveying Corporation, Houston, Tex a corporation of Texas Filed Oct. 30, 1959, Ser. No. 849,891 6 Claims. (Cl. 181-.5)

This invention relates to acoustic transducers and more particularly mechanical acoustic transducers for generating' acoustic energy in a well bore containing fluid.

It is an object of the present invention to provide new and improved mechanical transducer apparatus for developing acoustic energy in a well bore.

A mechanical acoustic transducer for borehole use as contemplated by the present invention includes a housing adapted for passage through a borehole and having a resiliently mounted, reciprocating piston member which acts upon the fluid in the well to develop pressure waves. The resilient mounting is such that high differential pressures on either side of the piston may be sustained. to permit the interior of the housing to be at atmospheric pressure so that movement of an inertia member in the housing to actuate the piston is not retarded.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings in which:

FIG. 1 shows a portion of a borehole apparatus in section embodying the present invention disposed in the borehole; and

FIG. 2 shows another embodiment of the present invention in section.

Referring now to FIG. 1, a suitable fluid-tight housing or support 10 (only a portion being shown) is adapted. to be transported through a bore 11 by means of a cable (not shown) and a winch (not shown) located at the surface of the earth in a customary manner. The bore 11 which traverses the earth formations contains the customary drilling fluid 13 which provides a medium for transmission of acoustic energy between the apparatus and the earth formations.

Housing 10 is generally tubular in shape and has a lower cylindrical end section 14. End section 14 is suitably hollowed out to receive a disc cam 15 mounted for rotation in the end section 14 and a hammer or inertia member 16 which is secured to one arm 17 of a bell crank 18. The bell crank 18 is pivotally mounted to the end section 14 and has another arm 19 which is in a contacting relationship to the cam 15 so as to function as a cam follower. A spring member 20 is also suitably secured to the end section 14 and has a portion thereof in contacting relationship with the crank arm 19 to resiliently bias the arm'into contact with the cam 15. The layout of cam 15 provides a surface 21 which lies in a plane A passing through the central axis of the disc and extending between

adjacent portions

22, 23 of the cam having different radii. The circumference of the cam 15 is defined by radii of increasing length starting from the smallest radius portion 22 adjacent surface 21 and going clockwise about the cam to the largest radius portion 23 adjacent to the surface 21.

Thus, when the cam 15 is rotated by a motor (not shown) in a counterclockwise manner, for example, a uniform angular displacement in a clockwise direction is imparted to the follower crank arm 19 which moves the hammer member- 16 along an arc until the follower crank arm rides past the largest radius portion 23 and surface 3,053,338 Patented Sept. 11, 1962 v 2 21 whereupon the hammer 16 is freeto drop. The

hammer 16 is provided with sufficient mass so that its momentum may be employed to impart mechanical energy to a piston member 33 to produce a pressure wave in the fluid. The interior of the housing end section 14 is preferably gas-filled at atmospheric pressure so that the movement of the hammer member is not impeded or retarded.

The outer, lower extremity of the housing end section 14 has a flat surface 25 which lies in a plane perpendicular to the sheet of drawing and at a preferred angle of 1130" relative to a vertical central axis through the end section 14. An opening extends between the interior wall 30 of the housing and flat surface 25 and has a central axis 26 which is transverse with respect to the vertical axis of the housing. Portions of the housing end section about the opening define first and second tion in a plane in which the axis 26 lies, the base or chord of the semicircular configuration lying on an imaginary conical surface about the axis 26 which would intersect the adjacent

circular edges

31 and 32 between

adjacent surfaces

28, 29 and 29, 27, respectively.

A piston member 33 having first and second

cylindrical portions

34 and 35 of different diameters is adapted to be slidably received by the first and second

cylindrical surfaces

27 and 28 and has an intermediate third portion 36 having a conical configuration and joining the first portion to the second portion. In the normal position of the piston member 33 the conical configuration will intersect the interconnection 32 between

surfaces

27, 29 and the conical angle of the conical configuration is less than the conical angle of the imaginary conical surface thereby to form a geometrical configuration. The geometrical configuration is bounded by the semicylindrical annular surface 2901: the housing and by a part of the second cylindrical portion 35 and the third portion 36 of the piston member 33. The cylindrical portion 35 of piston 24 also extends inwardly into the interior of the housing so as to be struck by the hammer member 16 when the hammer member is dropped while the forward surface 38 of the piston 24 generally does not extend beyond the fiat surface 25. The forward surface 38 is shown with a concavity which permits a substantially planar wave to be generated.

Within the geometrical configuration or volume defined by annular surface 29, the part of second cylindrical portion 37 and third portion 36 of piston member 33 is material 39 having a relatively high compressibility such as elastomers, for example, the material entirely filling the geometrical configuration. It will be noted that portions of the material in the volume have a greater diameter than the cylindrical portion 34 of the piston member 33 so that inward movement of the piston member applies a radial compressive force as well as an axial compressive force. Also, a relatively large contact area on the third portion of the piston member is provided to reduce the not be displaced inwardly to a point where the material does not resiliently support the member.

From the foregoing it will be appreciated that the transducer translates sound through a pressure resistant hOusing by means of a piston having a smaller area opening into the interior of the housing and a larger area opening to the exterior of the housing. The opening in the housing which receives the piston has an intermediate volume between the smaller and larger areas filled with material of relatively high compressibility which effectively pressure seals the piston in the housing yet permits the transmission of sound.

The inclination of the flat surface 25 at 11 30' from the vertical axis also inclines the central axis 26 of the piston member 33 at 11 30" from a horizontal axis. Thus, for very high-speed formations, i.e., about 25,000 feet per second the SOILJ energy is directed at the formations at the preferred critical angle which permits the most effective transmission of sound through the formations.

Referring now to FIG. 2 where corresponding elements to those of FIG. 1 are similarly identified, the material 39 is disposed adjacent the

cylindrical surfaces

27 and 28 and has an annular groove 40 opening to surface 29 which receives a relatively incompressible fluid 41 such as silicone oil which may be introduced to the groove via an opening 42.

While the above forms of the invention preferably entail bonding of the material in the volume between the piston member and housing, it should be appreciated that other techniques to fluid seal the piston member with respect to the housing may be effected within the practice of the present invention.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects, and therefore the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. An acoustic transducer system comprising: a pressure-resistant hollow housing having a first longitudinallyextending axis, said housing having an opening extending between its interior and exterior walls about a second axis'which is transverse with respect to said first axis, portions of said housing about said opening defining first and second cylindrical surfaces about said second axis having different diameters and opening respectively to the exterior and interior walls of the housing and terminating short of one another within the housing wall, the diameter of said first surface being greater than the diameter of said second section, said housing portions further defining an intermediate, third, annular surface interconnecting said first and second surfaces, a piston member having first and second cylindrical portions of different diameters adapted to be slidably received by said first and second cylindrical surfaces and an intermediate third portion joining said first portion to said second portion, said third annular surface of said housing and a part of said second cylindrical portion and said third portion of said piston member defining a volume therebetween, material having a relatively high compressibility filling said volume, and means in said housing for imparting mechanical energy to said piston member whereby a pressure wave may be produced in a well bore containing liquid.

2. An acoustic transducer system comprising: a pressure resistant hollow housing having a first longitudinallyextending axis, said housing having an opening extending between its interior and exterior walls about a second axis which is transverse with respect to said first axis, portions of said housing about said opening defining first and second cylindrical surfaces about said second axis exterior and interior walls of the housing and terminating short of one another within the housing wall, the diameter of said first surface being greater than the diameter of said second section, said housing portions further defining an intermediate, third, annular surface interconnecting said first and second surfaces, a piston member having first and second cylindrical portions of different diameters adapted to be slidably received by said first and second cylindrical surfaces and an intermediate third portion joining said first portion to said second portion, said third annular surface of said housing and a part of said second cylindrical portion and said third portion of said piston member defining a volume therebetween, material having a relatively high compressibility filling said volume, said material including elastic sealing portions disposed at each of said first and second cylindrical surfaces, and means in said housing for imparting mechanical energy to said piston member whereby a pressure wave may be produced in a well bore containing liquid.

3. An acoustic transducer system comprising: a fluidtight hollow housing having a first longitudinally-extending axis, said housing having an opening extending between its interior and exterior walls about a second axis which is transverse with respect to said first axis, portions of said housing about said opening defining first and second cylindrical surfaces about said second axis having different diameters and opening respectively to the exterior and interior walls of the housing and terminating short of one another within the housing wall, the diameter of said first surface being greater than the diameter of said second surface, said housing portions further defining an intermediate, third, annular surface interconnecting said first and second surfaces, said third surface having a curvilinear cross-sectional configuration when taken along a plane in which said second axis lies having a linear base lying on a first imaginary conical surface about said second axis which intersects the interconnections between adjacent surfaces and having portions of greater diameter than said diameter of said first surface, a piston member having first and second cylindrical portions of different diameters adapted to be slidably received by said first and second cylindrical surfaces and an intermediate third portion joining said first portion to said second porton, the junctions of said first and third portions lying on a second imaginary conical surface about said second axis, the conical angle of said second imaginary conical surface being less than the conical angle of said first imaginary conical surface thereby to form a geometrical configuration bounded by said curvilinear surface of said housing and by a portion of said second cylindrical portion and by said third portion of said piston member, an annular resilient member secured to said surfaces forming said geometrical configuration, and means in said housing for imparting mechanical energy to said piston member whereby a pressure wave may be produced in a well bore containing liquid.

4. An acoustic transducer system comprising: a fluidtight hollow housing having a first longitudinally-extending axis, said housing having an opening extending between its interior and exterior walls about a second axis which is trnasverse with respect to said first axis, portions of said housing about said opening defining first and second cylindrical surfaces about said second axis having different diameters and opening respectively to the exterior and interior walls of the housing and terminating short of one another within the housing wall, the diameter of said first surface being greater than the diameter of said second surface, said housing portions further defining an intermediate, third, annular surface interconnecting said first and second surfaces, said third surface having a curvilinear cross-sectional configuration when taken along a plane in which said second axis lies having a linear base lying on a first imaginary conical surface about said second axis which intersects the interhaving different diameters and opening respectively to the connections between adjacent surfaces and having portions of greater diameter than said diameter of said first surface, a piston member having first and second cylindrical portions of different diameters adapted to be slidably received by said first and second cylindrical surfaces and an intermediate third portion joining said first portion to said second portion, the junctions of said first and third portions and said second and third portions lying on a second imaginary conical surface about said second axis, the conical angle of said second imaginary conical surface being less than the conical angle of said first imaginary conical surface thereby to form a geometrical configuration bounded by said curvilinear surface of said housing and by a portion of said second cylindrical portion and by said third portion of said piston member, an annular resilient member secured to said surfaces forming said geometrical configuration, said member having an annular recess opening to said curvilinear surface, a relatively incompressible fluid received in said annular recess, and means in said housing for imparting mechanical energy to sad piston member whereby a pressure wave may be produced in a well bore containing liquid.

5. An acoustic transducer system comprising: a fluidtight hollow housing having a first longitudinally-extending axis, said housing having an opening extending between its interior and exterior walls about a second axis which is transverse with respect to said first axis, portions of said housing about said'opening defining first and second cylindrical surfaces about said second axis having different diameters and opening respectively to the exterior and interior walls of the housing and terminating short of one another within the housing wall, the diameter of said first surface being greater than the diameter of sad second surface, said housing portions further defining an intermediate and third, annular surface interconnecting said first and second surfaces, said third surface having a curvilinear cross-sectional configuration when taken along. a plane in which said second axis lies having a linear base lying on an imaginary conical surface about said second axis which intersects the interconnection between adjacent surfaces and having portions of greater diameter than said diameter of said first surface, a piston member having first and second cylindrical portions of different diameters adapted to be slidably received by said first and second cylindrical surfaces and an intermediate third portion having a generally conical configurationand joining said first portion to said second portion, the conical angle of said conical configuration being less than the conical angle of said imaginary conical surface thereby to form a geometrical configuration bounded by said curvilinear surface of said housing and by a portion of said second cylindrical portion and by said third portion of said piston member, an annular resilient member secured to said surfaces forming said geometrical configuration, and means in said housing for imparting mechanical energy to said piston member whereby a pressure wave may be produced in a well bore containing liquid.

6. An acoustic transducer system comprising: a fluidtight hollow housing having a first longitudinally-extending axis, said housing having an opening extending between its interior and exterior walls about a second axis which is transverse with respect to said first axis, portions of said housing about said opening defining first and second cylindrical surfaces about said second axis having difierent diameters and opening respectively to the exterior and interior walls of the housing and terminating short of one another within the housing wall, the diameter of said first surface being greater than the diameter of said second surface, said housing portions further defining an intermediate and third, annular surface interconnecting said first and second surfaces, said third surface having a somewhat semicircular cross-sectional configuration when taken along a plane in which said second axis lies, the base of said semicylindrical configuration lying on an imaginary conical surface about said second axis which intersects the interconnection between adjacent surfaces, a piston member having first and secondcylindrical portions of different diameters adapted to be slidably received by said first and second cylindrical surfaces and an intermediate third portion having a conical configuration and joining said first portion to said second portion, the conical angle of said conical configuration being less than the conical angle of said imaginary conical surface thereby to form a geometrical configuration bounded by said semicylindrical surface of said housing and by a portion of said second cylindrical portion and by said third portion of said piston member, an annular resilient member bonded to said surfaces forming said geometrical configuration, and means in said housing for imparting mechanical energy to said piston member wereby a pressure wave may be produced in a well bore containing liquid.

References Cited in the file of this patent UNITED STATES PATENTS Harris Aug. 2, 1960