Apparatus and method for determining velocity of acoustic waves in earth formations

Claim 2

Apparatus for determining the velocity of acoustic wave energy propagating in formations surrounding a borehole, comprising: means positioned in said borehole for establishing acoustic wave energy in said formations; means for receiving the acoustic wave energy at a plurality of spaced locations in the borehole; means for deriving a plurality for signals respectively representative of the wave energy received at said plurality of spaced locations in the borehole; means for correlating a first portion of the signal from one of said locations with first portions of signals from the other locations, the first portions of the signals from the other locations being determined from an assumed velocity, said correlating being performed for a number of different assumed velocities to obtain a resultant first provisional velocity; means for correlating a second portion of the signal from said one of said locations with second portions of signals from the other locations, the second portions of the signals from the other locations being determined from an assumed velocity, said correlating of second portions being performed for a number of different assumed velocities to obtain a resultant second provisional velocity; and means for generating an output velocity as a function of said first and second provisional velocities.

Claim 3

Apparatus as defined by claim 1 wherein said first and second portions of the signals are compressional wave components and the output velocity is an output compressional wave velocity.

Claim 4

Apparatus as defined by claim 1 wherein said first and second portions of the signals are shear wave components and the output velocity is an output shear wave velocity.

Claim 5

Apparatus as defined by claim 1 wherein said first and second portions each have a duration of substantially an intergral number of half-cycles, not exceeding two full cycles, of the signal from said one location.

Claim 6

Apparatus as defined by claim 1 wherein said output velocity is determined for each of a number of adjacent depth levels.

Claim 7

Apparatus as defined by claim 5 wherein said generated output velocity takes into account the output velocity previously generated at an adjacent depth level.

Claim 8

Apparatus as defined by claim 4 wherein said output velocity is determined for each of a number of adjacent depth levels.

Claim 9

Apparatus as defined by claim 7 wherein said generated output velocity takes into account the output velocity previously generated at an adjacent depth level.

Claim 10

Apparatus for determining the compressional wave velocity and the shear wave velocity of acoustic wave energy propagating in formations surrounding a borehole, comprising: source means positioned in said borehole for establishing acoustic wave energy in said formations; means for receiving the acoustic wave energy at a plurality of at least four spaced locations in the borehole; means for deriving a plurality of signals respectively representative of the wave energy received at said plurality of spaced locations in the borehole; means for correlating a first portion of the signal from the location closest to said source means with a first portion of each of the signals from the other locations, said first portions of the signals from the other locations being determined from an assumed compressional wave velocity, said correlation being performed for a number of different assumed compressional wave velocities, the assumed velocity which yields substantially the maximum correlation being selected as an output compressional wave velocity; means for correlating a second later-occurring portion of the signal from said closest location with second portions of each of the signals from the other locations, the second portions of the signals from the other locations being determined from an assumed shear wave velocity, said correlating of second portions being performed for a number of different assumed shear wave velocities, the assumed velocity which yields substantially the maximum correlation of second portions being selected as a first provisional shear wave velocity; means for correlating a third later-occurring portion of the signal from said closest location with third portions of each of the signals from the other locations, the third portions of the signals from the other locations being determined from an assumed shear wave velocity, said correlation of third portions being performed for a number of different assumed shear wave velocities, the assumed velocity which yields substantially the maximum correlation of third portions being selected as a second provisional shear wave velocity; and means for generating an output shear wave velocity as a function of said first and second provisional shear wave velocities.

Claim 11

Apparatus for determining the compressional wave velocity and the shear wave velocity of acoustic wave energy propagating in formations surrounding a borehole, comprising: source means positioned in said borehole for establishing acoustic wave energy in said formations; means for receiving the acoustic wave energy at a plurality of at least four spaced locations in the borehole; means for deriving a plurality of signals respectively representative of the wave energy received at said plurality of spaced locations in the borehole; means for correlating a first portion of the signal from the location closest to said source means with a first portion of each of the signals from the other locations, said first portions of the signals from the other locations being determined from an assumed compressional wave velocity, said correlation being performed for a number of different assumed compressional wave velocities, the assumed velocity which yields substantially the maximum correlation being selected as an output compressional wave velocity; means for correlating a second later-occurring portion of the signal from said closest location with second portions of each of the signals from the other locations, the second portions of the signals from the other locations being determined from an assumed shear wave velocity, said correlating of second portions being performed for a number of different assumed shear wave velocities, the assumed velocity which yields substantially the maximum correlation of second portions being selected as a first provisional shear wave velocity; means for correlating a third later-occurring portion of the signal from said closest location with third portions of each of the signals from the other locations, the third portions of the signals from the other locations being determined from an assumed shear wave velocity, said correlation of third portions being performed for a number of different assumed shear wave velocities, the assumed velocity which yields substantially the maximum correlation of third portions being selected as a second provisional shear wave velocity; and means for generating an output shear wave velocity as a function of said first and second provisional shear wave velocities.

Claim 12

Apparatus as defined by claim 9 wherein said first, second and third portions each have a duration of substantially an integral number of half-cycles, not exceeding two full cycles, of the signal from said closest location.

Claim 13

Apparatus as defined by claim 9 wherein said output velocities are determined for each of a number of adjacent depth levels.

Claim 14

Apparatus as defined by claim 11 wherein said generated output shear wave velocity takes into account the output shear wave velocity previously generated at an adjacent depth level.

Claim 15

Apparatus as defined by claim 10 wherein said output velocities are determined for each of a number of adjacent depth levels.

Claim 16

Apparatus as defined by claim 13 wherein said generated output shear wave velocity takes into account the output shear wave velocity previously generated at an adjacent depth level.

Claim 17

Apparatus as defined by claim 11 wherein said generated output compressional wave velocity takes into account the compressional wave velocity previously generated at an adjacent depth level.

Claim 18

Apparatus as defined by claim 12 wherein said generated output compressional wave velocity takes into account the compressional wave velocity previously generated at an adjacent depth level.

Claim 19

Apparatus as defined by claim 14 wherein said generated output compressional wave velocity takes into account the compressional wave velocity previously generated at an adjacent depth level.

Claim 20

Apparatus for determining the velocity of acoustic wave energy propagating in formations surrounding a borehole, comprising: means for deriving a plurality of signals respectively representative of acoustic wave energy received at a plurality of locations in the borehole spaced from a source of acoustic wave energy; means for correlating a first portion of the signal from one of said locations with first portions of signals from the other locations, the first portions of the signals from the other locations being determined from an assumed velocity, said correlating being performed for a number of different assumed velocities to obtain a resultant first provisional velocity; means for correlating a second portion of the signal from said one of said locations with second portions of signals from the other locations, the second portions of the signals from the other locations being determined from an assumed velocity, said correlating of second portions being performed for a number of different assumed velocities to obtain a resultant second provisional velocity; and means for generating an output velocity as a function of said first and second provisional velocities.

Claim 21

Apparatus for determining the velocity of acoustic wave energy propagating in formations surrounding a borehole, comprising: means for deriving a plurality of signals respectively representative of acoustic wave energy received at a plurality of locations in the borehole spaced from a source of acoustic wave energy; means for correlating a first portion of the signal from one of said locations with first portions of signals from the other locations, the first portions of the signals from the other locations being determined from an assumed velocity, said correlating being performed for a number of different assumed velocities to obtain a resultant first provisional velocity; means for correlating a second portion of the signal from said one of said locations with second portions of signals from the other locations, the second portions of the signals from the other locations being determined from an assumed velocity, said correlating of second portions being performed for a number of different assumed velocities to obtain a resultant second provisional velocity; and means for generating an output velocity as a function of said first and second provisional velocities.

Claim 22

Apparatus as definded by claim 18 wherein said first and second portions of the signals are compressional wave components and the output velocity is an output compressional wave velocity.

Claim 23

Apparatus as defined by claim 18 wherein said first and second portions of the signals are shear wave components and the output velocity is an output shear wave velocity.

Claim 24

Apparatus as defined by claim 18 wherein said first and second portions each have a duration of substantially an integral number of half-cycles, not exceeding two full cycles, of the signal from said one location.

Claim 25

Apparatus as defined by claim 18 wherein said output velocity value is determined for each of a number of adjacent depth levels.

Claim 26

Apparatus as defined by claim 22 wherein said generated output velocity value takes into account the output velocity previously generated at an adjacent depth level.

Claim 27

Apparatus as defined by claim 21 wherein said output velocity value is determined for each of a number of adjacent depth levels.

Claim 28

Apparatus as defined by claim 24 wherein said generated output velocity value takes into account the output velocity previously generated at an adjacent depth level.

Claim 29

Apparatus for determining the compressional wave velocity and the shear wave velocity of acoustic wave energy propagating in formations surrounding a borehole, comprising: means for deriving a plurality of at least four signals respectively representative of the wave energy received at a plurality of at least four locations in the borehole spaced from a source of acoustic wave energy; means for correlating a first portion of the signal from the location closest to said source with a first portion of each of the signals from the other locations, said first portions of the signals from the other locations being determined from an assumed compressional wave velocity, said correlation being performed for a number of different assumed compressional wave velocities, the assumed velocity which yields substantially the maximum correlation being selected as an output compressional wave velocity; means for correlating a second later-occurring portion of the signal from said closest location with second portions of each of the signals from the other locations, the second portions of the signals from the other locations being determined from an assumed shear wave velocity, said correlating of second portions being performed for a number of different assumed shear wave velocities, the assumed velocity which yields substantially the maximum correlation of second portions being selected as a first provisional shear wave velocity; means for correlating a third later-occurring portion of the signal from said closest location with third portions of each of the signals from the other locations, the third portions of the signals from the other locations being determined from an assumed shear wave velocity, said correlating of third portions being performed for a number of different assumed shear wave velocities, the assumed velocity which yields substantially the maximum correlation of third portions being selected as a second provisional shear wave velocity; and means for generating an output shear velocity as a function of said first and second provisional output velocities.

Claim 30

Apparatus for determining the compressional wave velocity and the shear wave velocity of acoustic wave energy propagating in formations surrounding a borehole, comprising: means for deriving a plurality of at least four signals respectively representative of the wave energy received at a plurality of at least four locations in the borehole spaced from a source of acoustic wave energy; means for correlating a first portion of the signal from the location closest to said source with a first portion of each of the signals from the other locations, said first portions of the signals from the other locations being determined from an assumed compressional wave velocity, said correlation being performed for a number of different assumed compressional wave velocities, the assumed velocity which yields substantially the maximum correlation being selected as an output compressional wave velocity; means for correlating a second later-occurring portion of the signal from said closest location with second portions of each of the signals from the other locations, the second portions of the signals from the other locations being determined from an assumed shear wave velocity, said correlating of second portions being performed for a number of different assumed shear wave velocities, the assumed velocity which yields substantially the maximum correlation of second portions being selected as a first provisional shear wave velocity; means for correlating a third later-occurring portion of the signal from said closest location with third portions of each of the signals from the other locations, the third portions of the signals from the other locations being determined from an assumed shear wave velocity, said correlating of third portions being performed for a number of different assumed shear wave velocities, the assumed velocity which yields substantially the maximum correlation of third portions being selected as a second provisional shear wave velocity; and means for generating an output shear velocity as a function of said first and second provisional output velocities.

Claim 31

Apparatus as defined by claim 26 wherein said first, second and third portions each have a duration of substantially an integral number of half-cycles, not exceeding two full cycles, of the signal from said one location.

Claim 32

Apparatus as defined by claim 26 wherein said output velocities are determined for each of a number of adjacent depth levels.

Claim 33

Apparatus as defined by claim 28 wherein said generated output shear wave velocity takes into account the output shear wave velocity previously generated at an adjacent depth level.

Claim 34

Apparatus as defined by claim 27 wherein said output velocities are determined for each of a number of adjacent depth levels.

Claim 35

Apparatus as defined by claim 30 wherein said generated output shear wave velocity takes into account the output shear wave velocity previously generated at an adjacent depth level.

Claim 36

Apparatus as defined by claim 28 wherein said generated output compressional wave velocity takes into account the compressional wave velocity previously generated at an adjacent depth level.

Claim 37

Apparatus as defined by claim 29 wherein said generated output compressional wave velocity takes into account the compressional wave velocity previously generated at an adjacent depth level.

Claim 38

Apparatus as defined by claim 31 wherein said generated output compressional wave velocity takes into account the compressional wave velocity previously generated at an adjacent depth level.

Claim 41

The method as defined by claim 35 wherein said first and second portions of the signals are compressional wave components and the output velocity is an output compressional wave velocity.

Claim 42

The method as defined by claim 35 wherein said first and second portions of the signals are shear wave components and the output velocity is an output shear wave velocity.

Claim 43

The method as defined by claim 35 wherein said first and second portions each have a duration of substantially an integral number of half-cycles, not exceeding two full cycles, of the signal from said one location.

Claim 44

The method as defined by claim 35 wherein said output velocity is determined for each of a number of adjacent depth levels.

Claim 45

The method as defined by claim 39 wherein said generated output velocity takes into account the output velocity previously generated at an adjacent depth level.

Claim 46

The method as defined by claim 38 wherein said output velocity is determined for each of a number of adjacent depth levels.

Claim 47

The method as defined by claim 41 wherein said generated output velocity takes into account the output velocity previously generated at an adjacent depth level.

Claim 50

The method as defined by claim 43 wherein said first, second and third portions each have a duration of substantially an integral number of half-cycles, not exceeding two full cycles of the signal from said closest location.

Claim 51

The method as defined by claim 43 wherein said output velocities are determined for each of a number of adjacent depth levels.

Claim 52

The method as defined by claim 45 wherein said generated output shear wave velocity takes into account the output shear wave velocity previously generated at an adjacent depth level.

Claim 53

The method as defined by claim 44 wherein said output velocities are determined for each of a number of adjacent depth levels.

Claim 54

The method as defined by claim 47 wherein said generated output shear wave velocity takes into account the output shear wave velocity previously generated at an adjacent depth level.

Claim 55

The method as defined by claim 45 wherein said generated output compressional wave velocity takes into account the compressional wave velocity previously generated at an adjacent depth level.

Claim 56

The method as defined by claim 46 wherein said generated output compressional wave velocity takes into account the compressional wave velocity previously generated at an adjacent depth level.

Claim 57

The method as defined by claim 48 wherein said generated output compressional wave velocity takes into account the compressional wave velocity previously generated at an adjacent depth level.

Claim 60

The method as defined by claim 52 wherein said first and second portions of the signals are compressional wave components and the output velocity is an output compressional wave velocity.

Claim 61

The method as defined by claim 52 wherein said first and second portions of the signals are shear wave components and the output velocity is an output shear wave velocity.

Claim 62

The method as defined by claim 52 wherein said first and second portions each have a duration of substantially an integral number of half-cycles, not exceeding two full cycles, of the signal from said one location.

Claim 63

The method as defined by claim 52 wherein said output velocity is determined for each of a number of adjacent depth levels.

Claim 64

The method as defined by claim 56 wherein said generated output velocity takes into account the output velocity previously generated at an adjacent depth level.

Claim 67

The method as defined by claim 58 wherein said first portion of said signal from one of said locations is substantially an integral number of half-cycles of said signal.

Claim 68

The method as defined by claim 59 wherein said second and third portions of said signal are substantially equal in duration to the first portion.

Claim 69

The method as defined by claim 58 wherein output velocity values are determined for each of a number of adjacent depth levels.

Claim 70

The method as defined by claim 60 wherein output velocity values are determined for each of a number of adjacent depth levels.

Claim 71

The method as defined by claim 61 wherein the output velocity values are selected taking into account the output velocity values previously generated at an adjacent depth level.

Claim 72

The method as defined by claim 62 wherein the output velocity values are selected taking into account the output velocity values previously generated at an adjacent depth level.

Claim 73

Apparatus for determining the velocities of different modes of propagation of acoustic wave energy propagating in formations surrounding a borehole, comprising: means positioned in said borehole for establishing acoustic wave energy in said formations; means for receiving the acoustic wave energy at a plurality of spaced locations in the borehole; means for deriving a plurality of signals respectively representative of the wave energy received at said plurality of spaced locations in the borehole; means for identifying the location and duration of a first characteristic portion of the signal from one of said locations; means for correlating said first portion of the signal from said one of said locations with first portions of signals from the other locations, the first portions of the signals from the other locations being determined from an assumed velocity, said correlating being performed for a number of different assumed velocities to obtain a resultant first provisional velocity; means for identifying subsequent characteristic portions of the signal from said one of said locations; means for correlating said subsequent portions of the signal from said one of said locations with subsequent portions of signals from the other locations, the subsequent portions of the signals from the other locations being determined from assumed velocities, said correlating of each of said subsequent portions being performed for a number of different assumed velocities to obtain resultant further provisional velocities; and means for generating output velocities of said different modes of propagation as a function of said first provisional velocity and said subsequent provisional velocities.

Claim 74

Apparatus for determining the velocities of different modes of propagation of acoustic wave energy propagating in formations surrounding a borehole, comprising: means positioned in said borehole for establishing acoustic wave energy in said formations; means for receiving the acoustic wave energy at a plurality of spaced locations in the borehole; means for deriving a plurality of signals respectively representative of the wave energy received at said plurality of spaced locations in the borehole; means for identifying the location and duration of a first characteristic portion of the signal from one of said locations; means for correlating said first portion of the signal from said one of said locations with first portions of signals from the other locations, the first portions of the signals from the other locations being determined from an assumed velocity, said correlating being performed for a number of different assumed velocities to obtain a resultant first provisional velocity; means for identifying subsequent characteristic portions of the signal from said one of said locations; means for correlating said subsequent portions of the signal from said one of said locations with subsequent portions of signals from the other locations, the subsequent portions of the signals from the other locations being determined from assumed velocities, said correlating of each of said subsequent portions being performed for a number of different assumed velocities to obtain resultant further provisional velocities; and means for generating output velocities of said different modes of propagation as a function of said first provisional velocity and said subsequent provisional velocities.

Claim 75

Apparatus as defined by claim 65 wherein said first portions of the signals are compressional wave components, the subsequent portions of the signals are shear wave components, and said output velocities are compressional and shear velocities.

Claim 76

Apparatus as defined by claim 66 wherein said first and subsequent portions each have a duration of substantially an integral number of half-cycles, not exceeding two full cycles, of said compressional and shear wave components, respectively.

Claim 77

Apparatus as defined by claim 65 wherein said output velocities are determined for each of a number of adjacent depth levels.

Claim 78

Apparatus as defined by claim 67 wherein said output velocities are determined for each of a number of adjacent depth levels.

Claim 79

Apparatus as defined by claim 68 wherein said generated output velocities are also a function of the output velocities previously generated at an adjacent depth level.

Claim 80

Apparatus as defined by claim 69 wherein said generated output velocities are also a function of the output velocities previously generated at an adjacent depth level.

Claim 81

Apparatus for determining the compressional wave velocity and the shear wave velocity of acoustic wave energy propagating in formations surrounding a borehole, comprising: source means positioned in said borehole for establishing acoustic wave energy in said formations; means for receiving the acoustic wave energy at a plurality of at least four spaced locations in the borehole; means for deriving a plurality of signals respectively representative of the wave energy received at said plurality of spaced locations in the borehole; means for identifying the location and duration of a first characteristic portion of the signal from the location closest to said source means; means for correlating said first portion of the signal from said closest location with a first portion of each of the signals from the other locations, said first portions of the signals from the other locations being determined from an assumed compressional wave velocity, said correlation being performed for a number of different assumed compressional wave velocities, the assumed velocity which yields substantially the maximum correlation being selected as an output compressional wave velocity; means for identifying subsequent characteristic portions of the signals from said closest location; means for correlating said subsequent portions of the signal from said closest location with subsequent portions of each of the signals from the other locations, the subsequent portions of the signals from the other locations being determined from assumed shear wave velocities, said correlating of each of said subsequent portions being performed for a number of different assumed shear wave velocities, the assumed velocities which yield substantially the maximum correlations of said subsequent portions being selected as provisional shear wave velocities; and means for generating an output shear wave velocity as a function of said provisional shear wave velocities.

Claim 82

Apparatus for determining the compressional wave velocity and the shear wave velocity of acoustic wave energy propagating in formations surrounding a borehole, comprising: source means positioned in said borehole for establishing acoustic wave energy in said formations; means for receiving the acoustic wave energy at a plurality of at least four spaced locations in the borehole; means for deriving a plurality of signals respectively representative of the wave energy received at said plurality of spaced locations in the borehole; means for identifying the location and duration of a first characteristic portion of the signal from the location closest to said source means; means for correlating said first portion of the signal from said closest location with a first portion of each of the signals from the other locations, said first portions of the signals from the other locations being determined from an assumed compressional wave velocity, said correlation being performed for a number of different assumed compressional wave velocities, the assumed velocity which yields substantially the maximum correlation being selected as an output compressional wave velocity; means for identifying subsequent characteristic portions of the signals from said closest location; means for correlating said subsequent portions of the signal from said closest location with subsequent portions of each of the signals from the other locations, the subsequent portions of the signals from the other locations being determined from assumed shear wave velocities, said correlating of each of said subsequent portions being performed for a number of different assumed shear wave velocities, the assumed velocities which yield substantially the maximum correlations of said subsequent portions being selected as provisional shear wave velocities; and means for generating an output shear wave velocity as a function of said provisional shear wave velocities.

Claim 83

Apparatus as defined by claim 72 wherein said first and subsequent portions each have a duration of substantially an integral number of half-cycles, not exceeding two full cycles, of said compressional and shear wave components, respectively.

Claim 84

Apparatus as defined by claim 73 wherein said output velocities are determined for each of a number of adjacent depth levels.

Claim 85

Apparatus as defined by claim 74 wherein said generated output shear wave velocity is also a function of the output shear wave velocity previously generated at an adjacent depth level.

Claim 86

An acoustic logging apparatus for determining the velocity of acoustic wave energy propagating in formations surrounding a borehole, comprising: an elongated support member movable through said borehole; an acoustic transmitter mounted on said support member for establishing acoustic wave energy in said formations; a plurality of acoustic receivers mounted in spaced relation on said support member; means for deriving a plurality of signals respectively representative of the acoustic wave energy received at said plurality of acoustic receivers; means for correlating a first portion of the signal from one of said receivers with first portions of signals from the other receivers, the first portions of the signals from the other receivers being determined from an assumed velocity, said correlating being performed for a number of different assumed velocities to obtain a resultant first provisional velocity; means for correlating a second portion of the signal from said one of said receivers with second portions of signals from the other receivers, the second portions of the signals from the other receivers being determined from an assumed velocity, said correlating of second portions being performed for a number of different assumed velocities to obtain a resultant second provisional velocity; means for generating an output velocity as a function of said first and second provisional velocities; means for recording said output velocity as a function of said first and second provisional velocities; and means for recording said output velocity in graphical form.

Claim 87

An acoustic logging apparatus for determining the velocity of acoustic wave energy propagating in formations surrounding a borehole, comprising: an elongated support member movable through said borehole; an acoustic transmitter mounted on said support member for establishing acoustic wave energy in said formations; a plurality of acoustic receivers mounted in spaced relation on said support member; means for deriving a plurality of signals respectively representative of the acoustic wave energy received at said plurality of acoustic receivers; means for correlating a first portion of the signal from one of said receivers with first portions of signals from the other receivers, the first portions of the signals from the other receivers being determined from an assumed velocity, said correlating being performed for a number of different assumed velocities to obtain a resultant first provisional velocity; means for correlating a second portion of the signal from said one of said receivers with second portions of signals from the other receivers, the second portions of the signals from the other receivers being determined from an assumed velocity, said correlating of second portions being performed for a number of different assumed velocities to obtain a resultant second provisional velocity; means for generating an output velocity as a function of said first and second provisional velocities; means for recording said output velocity as a function of said first and second provisional velocities; and means for recording said output velocity in graphical form.

Claim 88

Apparatus as defined by claim 76 wherein said first and second portions of the signals are compressional wave components and the output velocity is an output compressional wave velocity.

Claim 89

Apparatus as defined by claim 76 wherein said first and second portions of the signals are shear wave components and the output velocity is an output shear wave velocity.

Claim 90

Apparatus as defined by claim 76 wherein said first and second portions each have a duration of substantially an integral number of half-cycles, not exceeding two full cycles, of the signal from said one receiver.

Claim 91

Apparatus as defined by claim 76 wherein said output velocity is determined and recorded in graphical form for each of a number of adjacent depth levels.

Claim 92

Apparatus as defined by claim 80 wherein said generated output velocity takes into account the output velocity previously generated at an adjacent depth level.

Claim 93

Apparatus as defined by claim 79 wherein said output velocity is determined and recorded in graphical form for each of a number of adjacent depth levels.

Claim 94

Apparatus as defined by claim 82 wherein said generated output velocity takes into account the output velocity previously generated at an adjacent depth level.

Claim 95

An acoustic logging apparatus for determining the compressional wave velocity and the shear wave velocity of acoustic wave energy propagating in formations surrounding a borehole, comprising: an elongated support member movable through said borehole; an acoustic transmitter mounted on said support member for establishing acoustic wave energy in said formations; a plurality of acoustic receivers mounted in spaced relation of said support member; means for deriving a plurality of signals respectively representative of the acoustic wave energy received at said plurality of acoustic receivers; means for correlating a first portion of the signal from the receiver closest to the transmitter with a first portion of each of the signals from the other receivers, said first portions of the signals from the other receivers being determined from an assumed compressional wave velocity, said correlation being performed for a number of different assumed compressional wave velocities, the assumed velocity which yields substantially the maximum correlation being selected as an output compressional wave velocity; means for correlating a second later-occurring portion of the signal from said closest receiver with second portions of each of the signals from the other receivers, the second portions of the signals from the other receivers being determined from an assumed shear wave velocity, said correlating of second portions being performed for a number of different assumed shear wave velocities, the assumed velocity which yields substantially the maximum correlation of second portions being selected as a first provisional shear wave velocity; means for correlating a third later-occurring portion of the signal from said closest receiver with third portions or each of the signals from the other receivers, the third portions of the signals from the other receivers being determined from an assumed shear wave velocity, said correlation of third portions being performed for a number of different assumed shear wave velocities, the assumed velocity which yields substantially the maximum correlation of third portions being selected as a second provisional shear wave velocity; means for generating an output shear wave velocity as a function of said first and second shear wave velocities; and means for recording said output compressional wave velocity and said output shear wave velocity in graphical form.

Claim 96

An acoustic logging apparatus for determining the compressional wave velocity and the shear wave velocity of acoustic wave energy propagating in formations surrounding a borehole, comprising: an elongated support member movable through said borehole; an acoustic transmitter mounted on said support member for establishing acoustic wave energy in said formations; a plurality of acoustic receivers mounted in spaced relation of said support member; means for deriving a plurality of signals respectively representative of the acoustic wave energy received at said plurality of acoustic receivers; means for correlating a first portion of the signal from the receiver closest to the transmitter with a first portion of each of the signals from the other receivers, said first portions of the signals from the other receivers being determined from an assumed compressional wave velocity, said correlation being performed for a number of different assumed compressional wave velocities, the assumed velocity which yields substantially the maximum correlation being selected as an output compressional wave velocity; means for correlating a second later-occurring portion of the signal from said closest receiver with second portions of each of the signals from the other receivers, the second portions of the signals from the other receivers being determined from an assumed shear wave velocity, said correlating of second portions being performed for a number of different assumed shear wave velocities, the assumed velocity which yields substantially the maximum correlation of second portions being selected as a first provisional shear wave velocity; means for correlating a third later-occurring portion of the signal from said closest receiver with third portions or each of the signals from the other receivers, the third portions of the signals from the other receivers being determined from an assumed shear wave velocity, said correlation of third portions being performed for a number of different assumed shear wave velocities, the assumed velocity which yields substantially the maximum correlation of third portions being selected as a second provisional shear wave velocity; means for generating an output shear wave velocity as a function of said first and second shear wave velocities; and means for recording said output compressional wave velocity and said output shear wave velocity in graphical form.

Claim 97

Apparatus as defined by claim 84 wherein said first, second and third portions each have a duration of substantially an integral number of half-cycles, not exceeding two full cycles, of the signal from said closest receiver.

Claim 98

Apparatus as defined by claim 84 wherein said output velocities are determined and recorded in graphical form for each of a number of adjacent depth levels.

Claim 99

Apparatus as defined by claim 86 wherein said generated output shear wave velocity takes into account the output shear wave velocity previously generated at an adjacent depth level.

Claim 100

Apparatus as defined by claim 85 wherein said output velocities are determined and recorded in graphical form for each of a number of adjacent depth levels.

Claim 101

Apparatus as defined by claim 88 wherein said generated output shear wave velocity takes into account the output shear wave velocity previously generated at an adjacent depth level.

Claim 102

Apparatus as defined by claim 86 wherein said generated output compressional wave velocity takes into account the compressional wave velocity previously generated at an adjacent depth level.

Claim 103

Apparatus as defined by claim 87 wherein said generated output compressional wave velocity takes into account the compressional wave velocity previously generated at an adjacent depth level.

Claim 104

Apparatus as defined by claim 89 wherein said generated output compressional wave velocity takes into account the compressional wave velocity previously generated at an adjacent depth level.

Claim 105

For use in an acoustic logging technique wherein acoustic wave energy is established in formations surrounding a borehole and received at a plurality of spaced locations in the borehole, a method for converting a plurality of time varying recordings of signals representative of wave energy received at said plurality of spaced locations into a depth varying recording of the velocity of acoustic wave energy propagating in said formations, comprising the steps of: generating, at each depth level, a plurality of time varying recordings of signals repectively representative of the wave energy received at said plurality of spaced locations in the borehole; correlating, at each depth level, a first portion of the signal from one of said locations with first portions of signals from the other locations, the first portions of the signals from the other locations being determined from an assumed velocity, said correlating being performed for a number of different assumed velocities to obtain a resultant first provisional velocity at each depth level; correlating, at each depth level, a second portion of the signal from said one of said locations with second portions of signals from the other locations, the second portions of the signals from the other locations being determined from an assumed velocity, said correlating of second portions being performed for a number of different assumed velocities to obtain a resultant second provisional velocity at each depth level; generating an output velocity, at each depth level, as a function of said first and second provisional velocities; and generating a depth varying recording of said output velocity.

Claim 106

For use in an acoustic logging technique wherein acoustic wave energy is established in formations surrounding a borehole and received at a plurality of spaced locations in the borehole, a method for converting a plurality of time varying recordings of signals representative of wave energy received at said plurality of spaced locations into a depth varying recording of the velocity of acoustic wave energy propagating in said formations, comprising the steps of: generating, at each depth level, a plurality of time varying recordings of signals repectively representative of the wave energy received at said plurality of spaced locations in the borehole; correlating, at each depth level, a first portion of the signal from one of said locations with first portions of signals from the other locations, the first portions of the signals from the other locations being determined from an assumed velocity, said correlating being performed for a number of different assumed velocities to obtain a resultant first provisional velocity at each depth level; correlating, at each depth level, a second portion of the signal from said one of said locations with second portions of signals from the other locations, the second portions of the signals from the other locations being determined from an assumed velocity, said correlating of second portions being performed for a number of different assumed velocities to obtain a resultant second provisional velocity at each depth level; generating an output velocity, at each depth level, as a function of said first and second provisional velocities; and generating a depth varying recording of said output velocity.

Claim 107

The method as defined by claim 93 wherein said first and second portions of the signals are compressional wave components and the output velocity is an output compressional wave velocity.

Claim 108

The method as defined by claim 93 wherein said first and second portions of the signals are shear wave components and the output velocity is an output shear wave velocity.

Claim 109

The method as defined by claim 93 wherein said first and second portions each have a duration of substantially an integral number of half-cycles, not exceeding two full cycles, of the signal from said one location.

Claim 110

The method as defined by claim 94 wherein said first and second portions each have a duration of substantially an integral number of half-cycles, not exceeding two full cycles, of the signal from said one location.

Claim 111

The method as defined by claim 95 wherein said first and second portions each have a duration of substantially an integral number of half-cycles, not exceeding two full cycles, of the signal from said one location.