Patent US2470584A successfully refreshed from Google Patents.
EP0127548A2
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Low frequency sonic logging
Assignee: SLB NV
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Filing: 1984-05-29
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Granted: —
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Expires: 2004-05-29
Abstract
Abstract Methods and apparatus are described utilizing low frequency tube waves in determining characteristics of formations traversed by a borehole. Data received from three spaced receiving transducers are utilized in formulating quan- t i ties representative of complex compressibility of formations as well as loss parameters attributed to formation characteristics. When these two factors are recorded as a function of depth, interpretation is made readily available as to the permeability and rigidity of subsurface earth formations. Data is also provided by way of the present invention to enable interpretation concerning the presence of fractures or cracks in the earth formations. The methods and apparatus may also be utilized to examine the condition of casing in a borehole.
Inventors
- 👤 James E. White
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 17:44
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/40; G01V1/44
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
77 words
A method of sonic logging characterized by the steps of establishing tube waves within a borehole traversing earth formations, said tube waves having a fundamental frequency selected from the range of 20-100 hertz, detecting the appearance of said tube waves at at least three spaced apart locations within said borehole, producing electrical signals representative of the characteristics of the detected tube waves, and processing said electrical signals to generate indications of conditions of materials surrounding the borehole.
Claim 2
Independent Claim
77 words
A method of sonic logging characterized by the steps of establishing tube waves within a borehole traversing earth formations, said tube waves having a fundamental frequency selected from the range of 20-100 hertz, detecting the appearance of said tube waves at at least three spaced apart locations within said borehole, producing electrical signals representative of the characteristics of the detected tube waves, and processing said electrical signals to generate indications of conditions of materials surrounding the borehole.
Claim 3
Dependent Claim
49 words
The method of claim 1 cnaracterized in that the borehole is an open hole, the materials surrounding the borehole are earth formations and the particle velocity of the tube waves is detected at two outer locations and the pressure of the tube waves is detected at a center location.
Claim 4
Dependent Claim
66 words
The method of claim 2 characterized in that the electrical signals from the two outer locations are subtracted one from the other and a ratio taken of the averaged difference |E1| with respect to the averaged electrical signal from the center location |E2| to produce an output signal representative of the magnitude of the complex compressibility C of the earth formation adjacent said three detecting locations.
Claim 5
Dependent Claim
123 words
The method of claim 2 characterized by the steps of subtracting the electrical signals from the two outer locations one from the other to produce a signal El, multiplying the instantaneous values of El with the instantaneous values of a signal E2 derived from said detection of pressure, applying the product to a weignted moving average operator to produce a first function El E2, squaring the instantaneous values of the signal E2 and averaging to produce a second function E2 2 , and taking the ratio of said first function with respect to said second function to produce a first output signal representative of loss parameter L indicative of losses introduced by the characteristics of the earth formation adjacent said three detecting locations.
Claim 6
Dependent Claim
86 words
The method of claim 4 characterized by the steps of rectifying said signal El and applying the rectified signal to said weighted moving average operator, rectifying said signal E2 and applying the rectified signal to said weighted moving average operator, and taking the ratio of the averaged values of the signal El with respect to the averaged values of the signal E2 to produce a second output signal representative of the magnitude of the complex compressibility C of the earth formation adjacent said three detecting locations.
Claim 7
Dependent Claim
40 words
The method of claim 5 characterized by the step of taking the ratio of said first output signal with respect to said second output signal to produce a third output signal representing the quantitative values of said loss parameter L.
Claim 8
Dependent Claim
46 words
The method of claim 6 characterized in that said detecting locations are moved along the length of said borehole and the values of complex compressibility C and the quantitative values of said loss parameter L are recorded as a function of depth of saia detecting locations.
Claim 9
Dependent Claim
36 words
The method of claim 1 characterized in that the borehole is an open hole, the materials surrounding the borehole are earth formations and the pressure of the tube waves is detected at at least three locations.
Claim 10
Dependent Claim
156 words
The method of claim 8 characterized by the steps of subtracting twice the signal from the central location from the sum of the electrical signals from the outer two of the at least three locations to produce a signal El, rectifying said signal El and applying it to a weighted moving average operator to produce weighted average absolute values of said signal |E1| , producing a signal E2 representative of the pressure signal detected at the center one of said locations, rectifying said signal E2 and applying it to said weighted moving average operator to produce weighted average absolute values of said signal |E2| , and taking the ratio of said average values of El to the average values of said signal E2 to produce an output signal representative of the magnitude of the complex compressibility C of the earth formations adjacent said three detecting locations, and recording said output signal as a function of depth.
Claim 11
Dependent Claim
87 words
The method of claim 9 characterized by the steps of multiplying the average values of the signal El and the instantaneous values of the signal E2 to proauce product values, applying the product values to said weighted moving average operator to generate average values of the product, squaring the values of the signal E2 to produce a squared function, and taking the ratio of the average values of said product to average values of said squared function to produce an output signal representative of loss parameter L.
Claim 12
Dependent Claim
64 words
The method of claim 10 characterized by the steps of taking the ratio of said output signals representative of loss parameter L and said output signals representative of complex coopressibility C, multiplying the resultant ratio by 2π times the frequency of the tube waves, to determine quantitative values of loss parameter L, and recording the product as a function of depth along the borehole.
Claim 13
Independent Claim
23 words
The method of any one of claims 4-7 and 9-11 characterized in that said weighted moving average operator has a decreasing exponential characteristic.
Claim 14
Independent Claim
31 words
The method of any one of claims 1-12 characterized in that said tube waves are established by energizing a continuous wave vibrator located on the earth's surface closely adjacent said wellbore.
Claim 15
Independent Claim
32 words
The method of any one of claims 1-12 characterizea in that said tube waves are generated downhole at two points above and below said detecting locations and symmetrically arranged witn respect thereto.
Claim 16
Dependent Claim
15 words
The method of claim 14 characterizea in that said generated tube waves are in phase.
Claim 17
Independent Claim
21 words
The method of any one of claims 1-15 characterized in that said tube waves comprise continuous waves having a single frequency.
Claim 18
Independent Claim
25 words
The method of any one of claims 1-16 characterized in that the borehole is cased and the materials surrounding the borehole are strings of casing.
Claim 19
Dependent Claim
82 words
Apparatus for sonic logging characterized by means for establishing continuous tube waves within a borehole traversing earth formations, said tube waves having a fundamental frequency selected from the range of 20-100 hertz, means for detecting the appearance of said tube waves at at least three spaced apart locations within said borehole, means for producing electrical signals representative of the characteristics of the detected tube waves, and means for processing said electrical signals to generate indications of conditions of materials surrounding the borehole.
Claim 20
Dependent Claim
82 words
Apparatus for sonic logging characterized by means for establishing continuous tube waves within a borehole traversing earth formations, said tube waves having a fundamental frequency selected from the range of 20-100 hertz, means for detecting the appearance of said tube waves at at least three spaced apart locations within said borehole, means for producing electrical signals representative of the characteristics of the detected tube waves, and means for processing said electrical signals to generate indications of conditions of materials surrounding the borehole.
Claim 21
Dependent Claim
31 words
The apparatus of claim 18 characterized in that said detecting means includes a particle velocity uetector at each outer detecting location and a tube wave pressure aetector at a center location.
Claim 22
Dependent Claim
136 words
The apparatus of claim 19 characterized by means for subtracting signals from said particle velocity aetectors one from the otner to produce a signal E1,means for multiplying the instantaneous values of El with the instantaneous values of a signal E2 derived from saia pressure detector, means for applying the product to a weighted moving average operator to produce a first function E1 E2 , means for squaring the instantaneous values of the signal E2 and applying the squared values to said weighted moving average operator to produce a second function E2 2 , and means for taking the ratio of said first function with respect to said second function to produce a first output signal representative of loss parameter L indicative of losses introduced by the characteristics of the earth formation adjacent said three detecting locations.
Claim 23
Dependent Claim
85 words
The apparatus of claim 20 characterized by means for applying rectified values of said signal El to said weighted moving average operator, means for applying rectified values of said signal E2 to said weighted moving average operator, and means for taking the ratio of the averaged values of the signal El with respect to the averaged values of the signal E2 to produce a second output signal representative of the magnitude of the complex compressibility C of the earth formation adjacent said three detecting locations.
Claim 24
Dependent Claim
51 words
The apparatus of claim 21 characterized by means for taking the ratio of said first output signal with respect to said second output signal to produce a third output signal representing the quantitative values of said loss parameter L, and means for recording C and L as a function of depth.
Claim 25
Dependent Claim
19 words
The method of claim 18 characterized in that said detecting means comprises pressure detectors at each of the locations.
Claim 26
Dependent Claim
163 words
The apparatus of claim 23 characterized by means for subtracting twice the signal from the central location from the sum of the electrical signals from the outer two of the at least three locations to produce a signal El, means for applying rectified values of said signal El to a weighted moving average operator to produce weighted average absolute values of said signal |E1| , means for producing a signal E2 representative of the pressure signal detected at the center one of said locations, means for applying rectified values of said signal E2 to said weighted moving average operator to produce weighted average absolute values of said signal |E2| , and means for taking the ratio of said average values of El to the average values of said signal E2 to produce an output signal representative of the magnitude of the complex compressibility C of the earth formations adjacent said three detecting locations, and recording said output signal as a function of depth.
Claim 27
Dependent Claim
93 words
The apparatus of claim 24 characterized by means for multiplying the average values of the signal El and the instantaneous values of the signal E2 to produce product values, means for applying the product values to said weighted moving average operator to generate average values of the product, means for squaring the values of the signal E2 to produce a squarea function, and means for taking the ratio of the average values of said product to the average values of said squared function to produce an output signal representative of loss parameter L.
Claim 28
Dependent Claim
67 words
The apparatus of claim 25 characterized by means for taking the ratio between said output signals representative of loss parameter L and said output signals representative of complex compressibility C, means for multiplying the resultant ratios by 2 times the frequency of the tube waves, to determine quantitative values of loss parameter L, and means for recording the product as a function of depth along the borehole.
Claim 29
Independent Claim
29 words
The apparatus of any one of claims 18-26 characterized in that said means for establishing tube waves is a vibrator located on the earth's suface closely adjacent said wellbore.
Claim 30
Independent Claim
39 words
The apparatus of any one of claims 18-26 characterized in that said means for establishing tube waves includes a pair of downhole sources symmetrically arranged with respect to said detecting means and driven in phase one with the other.
References Cited (Backward Citations)
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