Acoustic method and device for determining permeability logs in bore-holes

Claim 2

In acoustic well logging wherein repetitive acoustic impulses from a source are each detected at a detector which is moved through a borehole in fixed spaced relationship with said source, to produce electrical signals, each having a first portion representative of a first arriving compressional wave having at least one component formed of a series of successive arches and a second portion representative of a later arriving shear wave, the method of determining mobility characteristics K/ Mu of the fluids impregnating the subsurface formations adjacent said borehole, comprising isolating from at least one and the same component of said compressional wave, one pair of arches from the three first arches of said component, producing a ratio signal representative of the ratio of corresponding values of the two arches of said pair of arches, and recording said ratio signal in correlation with depth to provide an information as to said mobility.

Claim 3

A method according to claim 1, wherein said ratio signal is substantially proportional to the ratio of the peak amplitudes of said two arches respectively.

Claim 4

A method according to claim 1, wherein said ratio signal is substantially proportional to the ratio of the slopes of said two arches respectively at their point of inflexion.

Claim 5

A method according to claim 1, wherein said ratio signal is substantially proportional to the ratio of the respective areas of said two arches.

Claim 6

A method for determining logs of mobility K/ Mu of the fluids saturating the geological formations surrounding a borehole, K being the permeability of these formations and Mu the viscosity of the saturating fluid, so as to evaluate this mobility for at least two different distances of penetration from the borehole wall, comprising at least two series of operations such that each series corresponds to the application of the method according to claim 1 with an emission frequency of the acoustic impulses which is different from that used for the other series.

Claim 7

Method for evaluating the variations in the viscosity of fluids impregnating a geological formation traversed by a borehole as a function of the distance of the impregnated zones of said formation from the borehole wall, consisting in successively transmitting at the level of this formation at least two acoustic impulses of different frequencies corresponding to different depths of penetration into said formation, receiving corresponding signals after propagation through said formation, determining for each received signal the ratio K/ Mu according to the method of claim 1 and recording the respective values of this ratio for said two signals in correlation with depth.

Claim 8

In acoustic well logging wherein repetitive acoustic impulses from a source are each detected at a detector which is moved through a borehole in fixed spaced relationship with said source, to produce electrical signals, each having a first portion representative of a first arriving compressional wave and a second portion representative of a later arriving shear wave having at least one component, the method of determining mobility characteristics of the fluids impregnating the subsurface formations adjacent said borehole, comprising, isolating from at least one and the same component of said shear wave one pair of adjacent arches of the same polarity, including the arch of maximum amplitude of said sheaR wave component.

Claim 9

In acoustic well logging wherein repetitive acoustic impulses from a source are each detected at a detector which is moved through a borehole in fixed spaced relationship with said source, to produce electrical signals, each having a first portion representative of a first arriving compressional wave and a second portion representative of a later arriving shear wave having at least one component, the method of determining mobility characteristics of the fluids impregnating the subsurface formations adjacent said borehole, comprising, isolating from at least one and the same component of said shear wave one pair of adjacent arches of the same polarity, including the arch of maximum amplitude of said sheaR wave component.

Claim 10

A method according to claim 7, wherein said ratio signal is substantially proportional to the ratio of the peak amplitudes of said two arches respectively.

Claim 11

A method according to claim 7, wherein said ratio signal is substantially proportional to the ratio of the respective areas of said two arches.

Claim 12

Method for evaluating the variations in the viscosity of fluids impregnating a geological formation traversed by a borehole as a function of the distance of the impregnated zones of said formation from the borehole wall, consisting in successively transmitting at the level of this formation at least two acoustic impulses of different frequencies corresponding to different depths of penetration into said formation, receiving corresponding signals after propagation through said formation, determining for each received signal the ratio K/ Mu according to the method of claim 7 and recording the respective values of this ratio for said two signals in correlation with depth.

Claim 13

In acoustic well logging wherein repetitive acoustic impulses from a source are each detected at a detector which is moved through a borehole in fixed spaced relationship with said source, to produce electrical signals, each having a first portion representative of a first arriving compressional wave and a second portion representative of a later arriving shear wave having at least one component, the method of determining mobility characteristics of the fluids impregnating the subsurface formations adjacent sad borehole, comprising, isolating from at least one and the same component of said shear wave one pair of adjacent arches of the same polarity, including the arch of maximum amplitude of said shear wave component, producing a ratio signal representative of the slopes of the tangents to the two arches of said pair at the respective points of inflexion of said arches, and recording said ratios and in correlation with depth to provide an information as to said mobility.

Claim 14

In acoustic well logging wherein repetitive acoustic impulses from a source are each detected at a detector which is moved through a borehole in fixed spaced relationship with said source, to produce electrical signals, each having a first portion representative of a first arriving compressional wave and a second portion representative of a later arriving shear wave having at least one component, the method of determining mobility characteristics of the fluids impregnating the subsurface formations adjacent sad borehole, comprising, isolating from at least one and the same component of said shear wave one pair of adjacent arches of the same polarity, including the arch of maximum amplitude of said shear wave component, producing a ratio signal representative of the slopes of the tangents to the two arches of said pair at the respective points of inflexion of said arches, and recording said ratios and in correlation with depth to provide an information as to said mobility.

Claim 15

A method for determining logs of mobility K/ Mu of the fluids saturating the geological formations surrounding a borehole, K being the permeability of these formations and Mu the viscosity of the saturating fluid, so as to evaluate this mobility for at least two different distances of penetration from the borehole wall, comprising at least two series of operations such that each series corresponds to the application of the method according to claim 11, with an emission frequency of the acoustic impulses which is different from that used for the other series.

Claim 16

Method for evaluating the variations in the viscosity of fluids impregnating a geological formation traversed by a borehole as a function of the distance of the impregnated zones of said formation from the borehole wall, consisting in successively transmitting at the level of this formation at least two acoustic impulses of different frequencies corresponding to different depths of penetration into said formation, receiving corresponding signals after propagation through said formation, determining for each received signal the ratio K/ Mu according to the method of claim 11 and recording the respective values of this ratio for said two signals in correlation with depth.

Claim 17

A method for determining logs of mobility K/ Mu of the fluids saturating the geological formations surrounding a borehole, K being the permeability of these formations and Mu the viscosity of the saturating fluid, so as to evaluate this mobility for at least two different distances of penetration from the borehole wall, comprising at least two series of operations such that each series corresponds to the application of the method according to claim 7 with an emission frequency of the acoustic impulses which is different from that used for the other series.

Claim 18

In acoustic well logging wherein repetitive acoustic impulses from a source are each detected at a detector which is moved through a borehole to produce electrical signals, each having a first portion representative of a first arriving compressional wave having at least one component and a second portion representative of a later arriving compressional wave having at least one component, said first and second portions each consisting of a series of successive arches, the method of determining at least a value derived from fixed arches of selected components of each of said signals, comprising the steps of transmitting a first acoustic impulse at a high frequency from said source, receiving at the detector at least one corresponding first electrical signal where of the components are distinctly separated from one another, transmitting from said source at least one second acoustic impulse at a lower frequency than that of said first acoustic impulse, said second frequency corresponding to a higher penetration of said second impulse into the ground, receiving at least one corresponding second signal at the receiver, the components of which are located closer to one another than that of said first signal, separating the component of said second signal by a correlation between said first and second signals, producing a ratio signal representative of the ratio of corresponding values of the two arches of said pair of arches, and recording said ratio signal in correlation with depth to provide an information as to said mobility.

Claim 19

In acoustic well logging wherein repetitive acoustic impulses from a source are each detected at a detector which is moved through a borehole to produce electrical signals, each having a first portion representative of a first arriving compressional wave having at least one component and a second portion representative of a later arriving compressional wave having at least one component, said first and second portions each consisting of a series of successive arches, the method of determining at least a value derived from fixed arches of selected components of each of said signals, comprising the steps of transmitting a first acoustic impulse at a high frequency from said source, receiving at the detector at least one corresponding first electrical signal where of the components are distinctly separated from one another, transmitting from said source at least one second acoustic impulse at a lower frequency than that of said first acoustic impulse, said second frequency corresponding to a higher penetration of said second impulse into the ground, receiving at least one corresponding second signal at the receiver, the components of which are located closer to one another than that of said first signal, separating the component of said second signal by a correlation between said first and second signals, producing a ratio signal representative of the ratio of corresponding values of the two arches of said pair of arches, and recording said ratio signal in correlation with depth to provide an information as to said mobility.

Claim 26

In acoustic well logging wherein repetitive acoustic impulses from a source are each detected at a detector which is moved through a borehole in fixed spaced relationship with said source, to produce electrical signals, each having a first portion representative of a first arriving compressional wave having at least one component formed of series of successive arches and a second portion representative of a later arriving shear wave, in combination with an automatic data-processing system determining mobility characteristics K/ Mu of the fluids impregnating the subsurface formations adjacent said borehole, the method comprising isolating from at least one and the same component of said compressional wave one pair of arches from the three first arches of said component, producing in said automatic data-processing system a value representative of the ratio of corresponding values of the two arches of each pair one by the other, and recording said value in correlation with depth to provide information as to said mobility.

Claim 27

In acoustic well logging wherein repetitive acoustic impulses from a source are each detected at a detector which is moved through a borehole in fixed spaced relationship with said source, to produce electrical signals, each having a first portion representative of a first arriving compressional wave having at least one component formed of series of successive arches and a second portion representative of a later arriving shear wave, in combination with an automatic data-processing system determining mobility characteristics K/ Mu of the fluids impregnating the subsurface formations adjacent said borehole, the method comprising isolating from at least one and the same component of said compressional wave one pair of arches from the three first arches of said component, producing in said automatic data-processing system a value representative of the ratio of corresponding values of the two arches of each pair one by the other, and recording said value in correlation with depth to provide information as to said mobility.

Claim 28

A method according to claim 19, wherein said corresponding values are substantially proportional to the peak amplitude of said two arches respectively.

Claim 29

A method according to claim 19, wherein said corresponding values are substantially proportional to the slope of said two arches respectively at their point of inflexion.

Claim 30

A method according to claim 19, wherein said corresponding values are substantially proportional to the respective areas of said two arches.

Claim 31

In acoustic well logging wherein repetitive acoustic impulses from a source are each detected at a detector which is moved through a borehole in fixed spaced relationship with said source, to produce electrical signals, each having a first portion representative of a first arriving compressional wave and a second portion representative of a later arriving shear wave having at least on component, in combination with an automatic data-processing system determining mobility characteristics of the fluids impregnating the subsurface formations adjacent said borehole, the method comprising isolating from at least one the same component of said shear wave one pair of adjacent arches of the same polarity, including the arch of maximum amplitude of said shear wave component, producing in said automatic data-processing system a value representative of the ratio of corresponding values of the two arches of each pair one by the other, and recording said value in correlation with depth to provide information as to said mobility.

Claim 32

In acoustic well logging wherein repetitive acoustic impulses from a source are each detected at a detector which is moved through a borehole in fixed spaced relationship with said source, to produce electrical signals, each having a first portion representative of a first arriving compressional wave and a second portion representative of a later arriving shear wave having at least on component, in combination with an automatic data-processing system determining mobility characteristics of the fluids impregnating the subsurface formations adjacent said borehole, the method comprising isolating from at least one the same component of said shear wave one pair of adjacent arches of the same polarity, including the arch of maximum amplitude of said shear wave component, producing in said automatic data-processing system a value representative of the ratio of corresponding values of the two arches of each pair one by the other, and recording said value in correlation with depth to provide information as to said mobility.

Claim 33

A method according to claim 23, wherein said corresponding values are substantially proportional to the peak amplitude of said two arches respectively.

Claim 34

A method according to claim 23, wherein said corresponding values are substantially proportional to the respective areas of said two arches.

Claim 35

In acoustic well logging wherein repetitive acoustic impulses from a source are eaCh detected at a detector which is moved through a borehole in fixed spaced relationship with said source, to produce electrical signals, each having a first portion representative of a first arriving compressional wave and a second portion representative of a later arriving shear wave having at least one component, in combination with an automatic data-processing system determining mobility characteristics of the fluids impregnating the subsurface formations adjacent said borehole, the method comprising isolating from at least one and the same component of said shear wave one pair of adjacent arches of the same polarity, including the arch of maximum amplitude of said shear wave component, producing in said automatic data-processing system a value representative of the ratio one by the other of the values of the slopes of the tangents to the two arches of said parts at the respective points of inflexion of said arches, and recording said value in correlation with depth to provide information as to said mobility.

Claim 36

In acoustic well logging wherein repetitive acoustic impulses from a source are eaCh detected at a detector which is moved through a borehole in fixed spaced relationship with said source, to produce electrical signals, each having a first portion representative of a first arriving compressional wave and a second portion representative of a later arriving shear wave having at least one component, in combination with an automatic data-processing system determining mobility characteristics of the fluids impregnating the subsurface formations adjacent said borehole, the method comprising isolating from at least one and the same component of said shear wave one pair of adjacent arches of the same polarity, including the arch of maximum amplitude of said shear wave component, producing in said automatic data-processing system a value representative of the ratio one by the other of the values of the slopes of the tangents to the two arches of said parts at the respective points of inflexion of said arches, and recording said value in correlation with depth to provide information as to said mobility.