EP0375549B1
Expired / Lapsed
EP
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Method and apparatus for performing acoustic investigations in a borehole
Assignee: SLB NV
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Filing: 1989-12-20
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Granted: 1994-05-25
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Expires: 2009-12-20
Abstract
No abstract record available.
Inventors
- 👤 Sergio Kostek
- 👤 Shu-Kong Chang
- 👤 Gordon Mcdaniel
- 👤 Thomas Plona
- 👤 Curtis Randall
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 00:22
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/40; G01V1/52; G01V1/523
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
156 words
An apparatus (30) for performing acoustic investigations of subsurface geological formations during the excavation of a borehole, the apparatus (30) characterized by: a. a cylindrical drill collar (32) with a longitudinal axis (51) and having an acoustic frequency stop band in a frequency range over which acoustic propagation along said collar (32) is depressed, wherein said frequency range is a function of the geometry of said collar (32); b. a transmitter (34) mounted on said collar (32) for preferentially transmitting acoustic energy at a frequency within said stop band at an angle to said axis (51), said transmitter (34) being mounted to be substantially free of acoustic coupling with said collar (32); and c. a receiver (36) mounted on said collar (32) and spaced from said transmitter (34) for preferentially receiving acoustic energy at said frequency within said stop band, said receiver (36) being mounted to be substantially free of acoustic coupling with said collar (32).
Claim 2
Dependent Claim
53 words
The apparatus (30) as recited in claim 1 wherein said collar (32) comprises axially periodic, substantially circumferentially continuous grooves (40) formed on the interior of said collar (32) intermediate said transmitter (34) and said receiver (36) for causing destructive wave interference in said collar (32) at the frequency range of said stop band.
Claim 3
Dependent Claim
53 words
The apparatus (30) as recited in claim 1 wherein said collar (32) comprises axially periodic, substantially circumferentially continuous grooves (40) formed on the exterior of said collar (32) intermediate said transmitter (34) and said receiver (36) for causing destructive wave interference in said collar (32) at the frequency range of said stop band.
Claim 4
Dependent Claim
17 words
The apparatus (30) as recited in claim 3 wherein said grooves (40) have rounded interior corners (46).
Claim 5
Dependent Claim
26 words
The apparatus (30) as recited in claim 1 further including means (48) an said collar (32) for enhancing said stop band by producing destructive wave interference.
Claim 6
Dependent Claim
30 words
The apparatus (30) as recited in claim 1 wherein said collar (32) comprises a plurality of randomly spaced depressions (70) formed in said collar (32) for enhancing said stop band.
Claim 7
Dependent Claim
67 words
The apparatus (30) as recited in claim 1 wherein said transmitter (34) comprises an acoustic transmitter transducer (56) and transmitter transducer mounting means for reducing the acoustic coupling between said transmitter transducer (56) and said collar (32), and; wherein said receiver (36) comprises an acoustic receiver transducer (58) and receiver transducer mounting means for reducing the acoustic coupling between said receiver transducer (58) and said collar (32).
Claim 8
Dependent Claim
20 words
The apparatus (30) as recited in claim 7 wherein said transmitter transducer (56) is mounted transversely of said collar (32).
Claim 9
Dependent Claim
69 words
The apparatus (30) as recited in claim 7 wherein said transmitter transducer mounting means comprises resilient means (60) intermediate said transmitter transducer (56) and said collar (32) for acoustically isolating said transmitter transducer (56) from said collar (32); and wherein said receiver transducer mounting means comprises resilient means (60) intermediate said receiver transducer (58) and said collar (32) for acoustically isolating said receiver transducer (58) from said collar (32).
Claim 10
Dependent Claim
29 words
The apparatus (30) as recited in claim 9 wherein said transmitter transducer (56) is mounted in a tube (52) and said tube (52) is mounted in said collar (32).
Claim 11
Dependent Claim
17 words
The apparatus (30) as recited in claim 10 wherein said tube (52) radially traverses said collar (32).
Claim 12
Dependent Claim
27 words
The apparatus (30) as recited in claim 10 wherein said resilient means (60) creates a fluid-filled gap (57) between said transmitter transducer (56) and said collar (32).
Claim 13
Dependent Claim
52 words
The apparatus (30) as recited in claim 1 wherein said collar (32) comprises axially discontinuous portions (48) with acoustic wave propagation characteristics different from those of said collar (32), said portions (48) being sized and spaced to cause destructive wave interference in said collar (32) at the frequency of said stop band.
Claim 14
Dependent Claim
21 words
The apparatus (30) as recited in claim 13 wherein said portions (48) extend inwardly from the exterior of said collar (32).
Claim 15
Dependent Claim
21 words
The apparatus (30) as recited in claim 13 wherein said portions (48) extend outwardly from the interior of said collar (32).
Claim 16
Dependent Claim
27 words
The apparatus (30) as recited in claim 13 wherein said portions (48) are grooves (40) which contain a material dissimilar from the material of said collar (32).
Claim 17
Dependent Claim
17 words
The apparatus (30) as recited in claim 13 wherein said axially discontinuous portions (48) have spiral configurations.
Claim 18
Dependent Claim
29 words
The apparatus (30) as recited in claim 1 wherein said transmitter (34) is mounted on said collar (32) to emit acoustic energy substantially normal to said longitudinal axis (51).
Claim 19
Dependent Claim
22 words
The apparatus (30) as recited in claim 1 wherein said frequency within said stop band is in the range of 3-30 kilohertz.
Claim 20
Dependent Claim
61 words
The apparatus (30) as recited in claim 1 wherein said frequency (f) within said stop band is determined in accordance with the following relationship: f = kV/(d₁+d₂) where k = 2/π, V = the bar extensional wave velocity of the collar (32), d₁ = the inner diameter of the collar (32), and d₂ = the outer diameter of the collar (32).
Claim 21
Dependent Claim
77 words
The apparatus (30) as recited in claim 13 wherein said portions (48) have equal axial widths (L₂) and axial spacings (L₁) one from another which are determined in accordance with the following relationship: L₁ = L₂ = 1/(4fS) where L₂= the axial width of a portion (48) = the axial spacing, L₁, between portions (48), f = the frequency within said stop band, and S = the slowness of an acoustic wave propagating in said collar (32).
Claim 22
Independent Claim
96 words
A method for performing sonic logging investigations of geological formations traversed by a borehole, comprising the steps of: a. preferentially transmitting acoustic energy into the formation at a predetermined frequency from a first location on a cylindrical body in said borehole; b. receiving acoustic energy from said formation at a second location on said body; and c. attenuating, at a location intermediate said first and second locations, acoustic energy in a stop band spanning said predetermined frequency, wherein the frequency range of said stop band is a naturally occurring function of the geometry of said body.
Claim 23
Dependent Claim
18 words
The method as recited in claim 22 wherein said attenuating step occurs by means of destructive wave interference.
Claim 24
Dependent Claim
24 words
The method as recited in claim 22 wherein said receiving step includes preferentially receiving acoustic energy over a frequency band spanning said stop band.
Claim 25
Dependent Claim
24 words
The method as recited in claim 22 wherein said acoustic energy is transmitted and received substantially normally to the longitudinal axis of said body.
References Cited (Backward Citations)
No citation records indexed.
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