Well logging methods and apparatus

Claim 2

A well logging system comprising: a well logging tool having transducer means, means for repetitively energizing said transducer means to emit acoustic energy into a media surrounding said well tool, means for producing a transmitted energy sync signal representative of the time that said energy is emitted, means coupled to said transducer means for producing a received energy signal representative of at least a portion of the emitted energy which is returned to said well tool; signal processing means responsive to at least one of said sync and received energy signals for producing a measurement signal representative of a characteristic of at least part of the media surrounding said well tool; means for measuring at least one parameter of the media surrounding said well tool which affects the accuracy of said measurement signal and producing a control signal representative of said parameter; and means responsive to said control signal for adjusting a parameter of said signal processing means to compensate for changes in said parameter of the surrounding media.

Claim 3

The apparatus of claim 1 wherein said signal processing means includes means responsive to the amplitude of said received energy signals for providing information regarding at least a portion of the media surrounding said well tool; and wherein said control signal producing means includes means responsive to the time separation between at least some sets of sync and received energy signals for producing said control signal; and wherein said means for adjusting includes means responsive to said control signal for adjusting the amplitude of said received energy signals to compensate for variations in well bore diameter.

Claim 4

The apparatus of claim 1 wherein said means for producing a control signal includes an acoustic transmitter and at least two acoustic receivers carried by said well tool and spaced apart from each other and from said acoustic transmitter, means for repetitively energizing said acoustic transmitter to emit acoustic energy into the media surrounding said well tool, said acoustic receivers adapted to receive at least some of said emitted acoustic energy from said acoustic transmitter which passes through the well bore fluid and produce electrical signals representative thereof, means responsive to said electrical signals produced by said acoustic receivers for producing said control signal used to adjust a parameter of said signal processing means.

Claim 5

The apparatus of claim 3 wherein said signal processing means includes means responsive to the amplitude of at least some of said received energy signals for providing information concerning at least a portion of the media surrounding said well tool; and wherein said means responsive to said electrical signals for producing said control signal includes means for measuring the amplitude difference between the signals produced by each of said acoustic receivers and producing said control signal in proportion to said measured amplitude difference, said control signal operating on said signal processing means to adjust the amplitude of at least some of said received energy signals to theReby compensate for variations in the acoustic impedance of the wellbore fluid surrounding said well tool.

Claim 6

The apparatus of claim 3 wherein said signal processing means includes means responsive to the time separation between selected sync and received energy signals for producing measurements representative of the cross-section of a well bore; and wherein said means responsive to said electrical signals for producing a control signal includes means for measuring the time separation between said electrical signals produced by said two acoustic receivers and producing said control signal in proportion to said measured time separation, said control signal operating on said signal processing means to compensate said cross-section measurements for variations in the acoustic velocity of the well bore fluid surrounding said well tool.

Claim 7

The apparatus of claim 1 wherein said means for producing a control signal includes acoustic reflector means supported by said well tool and positioned between said transducer means and a well bore wall for reflecting at least a portion of acoustic energy back to said transducer means to produce a second received energy signal, and means responsive to at least said second received energy signal for producing said control signal for application to said signal processing means to compensate for changes in an acoustic parameter of the fluid in a well bore.

Claim 8

In a well logging system, apparatus for compensating acoustic well logging measurements for variations in the cross-section of a well bore, comprising: a well logging tool having transducer means, means for repetitively energizing said transducer means to emit acoustic energy into a media surrounding said well tool, means for rotating said transducer means so that said emitted energy will be sequentially directed at various circumferential portions of a well bore wall, means for producing transmitted energy sync signals representative of the times that said energy is emitted, means coupled to said transducer means for producing a received energy signal representative of that portion of the emitted energy which is returned to said well tool for each energy emission, the sync and received energy signals produced for each emission of energy comprising a set of sync and received energy signals; means for measuring the time separation between at least some sets of sync and received energy signals to produce a control signal representative of said time separation; and means responsive to said time separation signal for adjusting the amplitude of said received energy signals to compensate said received energy signals for variations in the cross-section of said well bore.

Claim 9

In a well logging system, apparatus for compensating acoustic well logging measurements for variations in the cross-section of a well bore, comprising: a well logging tool having transducer means, means for repetitively energizing said transducer means to emit acoustic energy into a media surrounding said well tool, means for rotating said transducer means so that said emitted energy will be sequentially directed at various circumferential portions of a well bore wall, means for producing transmitted energy sync signals representative of the times that said energy is emitted, means coupled to said transducer means for producing a received energy signal representative of that portion of the emitted energy which is returned to said well tool for each energy emission, the sync and received energy signals produced for each emission of energy comprising a set of sync and received energy signals; means for measuring the time separation between at least some sets of sync and received energy signals to produce a control signal representative of said time separation; and means responsive to said time separation signal for adjusting the amplitude of said received energy signals to compensate said received energy signals for variations in the cross-section of said well bore.

Claim 10

The apparatus of claim 7 wherein said means for measuring the time separation to produce a control signal includes time to amplitude converter means responsive to at least some sets of said sync and received energy signals for converting the time separation between said sets of signals to a control signal whose amplitude is representative of said time separation; and wherein said means for adjusting the amplitude of said received energy signals includes variable gain means responsive to said control signal for varying the amplitude of said received energy signals as a function of the amplitude of said control signal to thereby compensate said received energy signals for variations in well bore cross-section.

Claim 11

A well logging system comprising: a well logging tool having transducer means, means for repetitively energizing said transducer means to emit acoustic energy into a media surrounding said well tool, means for rotating said transducer means so that said emitted energy will be sequentially directed at various circumferential portions of a well bore wall, means for producing transmitted energy sync signals representative of the times that said energy is emitted, means coupled to said transducer means for producing a received energy signal representative of that portion of the emitted energy which is returned to said well tool for each emission of energy; signal processing means responsive to at least one of said sync and received energy signals for producing a signal representative of a characteristic of at least part of the media surrounding said well tool; an acoustic transmitter and two acoustic receivers supported by said well tool, means for repetitively energizing said acoustic transmitter to emit acoustic energy into the media surrounding said well tool, said acoustic receivers adapted to receive at least some of said emitted acoustic energy from said acoustic transmitter and produce electrical signals representative thereof; means responsive to said electrical signals produced by said acoustic receivers for producing a control signal representative of an acoustic parameter of the fluid in a well bore; and adjusting means responsive to said control signal for adjusting a parameter of said signal processing means to compensate for changes in said well bore fluid acoustic parameter.

Claim 12

A well logging system comprising: a well logging tool having transducer means, means for repetitively energizing said transducer means to emit acoustic energy into a media surrounding said well tool, means for rotating said transducer means so that said emitted energy will be sequentially directed at various circumferential portions of a well bore wall, means for producing transmitted energy sync signals representative of the times that said energy is emitted, means coupled to said transducer means for producing a received energy signal representative of that portion of the emitted energy which is returned to said well tool for each emission of energy; signal processing means responsive to at least one of said sync and received energy signals for producing a signal representative of a characteristic of at least part of the media surrounding said well tool; an acoustic transmitter and two acoustic receivers supported by said well tool, means for repetitively energizing said acoustic transmitter to emit acoustic energy into the media surrounding said well tool, said acoustic receivers adapted to receive at least some of said emitted acoustic energy from said acoustic transmitter and produce electrical signals representative thereof; means responsive to said electrical signals produced by said acoustic receivers for producing a control signal representative of an acoustic parameter of the fluid in a well bore; and adjusting means responsive to said control signal for adjusting a parameter of said signal processing means to compensate for changes in said well bore fluid acoustic parameter.

Claim 13

The apparatus of claim 9 wherein said signal processing means includes means responsive to the amplitudes of at least some of said received energy signals for providing information concerning at least a portion of the media surrounding said well tool; and wherein said means responsive to said electrical signals for producing a control signal includes means for measuring the amplitude difference between the signals produced by each of said acoustic receivers and producing said control signal in proportion to said measured amplitude difference, said control signal operating on said signal processing means to adjust the amplitude of at least some of said received energy signals to thereby compensate for variations in the acoustic impedance of the well bore fluid surrounding said well tool.

Claim 14

The apparatus of claim 9 wherein said signal processing means includes means responsive to the time separation between selected sync and received energy signals for producing measurements representative of the cross-section of a well bore, and wherein said means responsive to said electrical signals for producing a control signal includes means for measuring the time separation between said electrical signals produced by said two acoustic receivers and producing said control signal in proportion to said measured time separation, said control signal operating on said signal processing means to compensate said cross-section measurements for variations in the acoustic velocity of the well bore fluid surrounding said well tool.

Claim 15

The apparatus of claim 10 wherein said means for measuring said amplitude difference includes means operative in a time relationship with the energization of said acoustic transmitter for sampling the amplitude of a selected portion of said electrical signal produced by each of said acoustic receivers, means for subtracting the sampled amplitude of the electrical signal from one of said acoustic receivers from that produced by the other of said acoustic receivers to produce a difference signal, low pass filter means for filtering said difference signal to produce said control signal; and wherein said adjusting means includes variable means for adjusting the amplitude of said received energy signals as a function of the amplitude of said control signal to compensate for variations in well bore fluid impedance.

Claim 16

The apparatus of claim 9 wherein said signal processing means includes means responsive to said sync and received energy signals for generating a pulse of a substantially constant current having a time duration representative of the time spacing between successive sync and received energy signals, integrator means responsive to said current pulse for producing a signal whose amplitude is representative of said time spacing, and output means responsive to said time spacing representative signal for producing an output signal representative of the cross-section of a well bore; and wherein said control signal prOducing means includes means operative in a time relationship with the energization of said acoustic transmitter for separating the electrical signals produced by each of said acoustic receivers, time to amplitude conversion means responsive to said separated electrical signals for producing a signal representative of the time separation between successive ones of said separated electrical signals, and low pass filter means responsive to said time separation representative signal for producing said control signal; and wherein said adjusting means includes means for varying the magnitude of current applied to said integrator means in response to said control signal to thereby compensate cross-section representative output signal for variations in the well bore fluid acoustic velocity.

Claim 17

A well logging system comprising: a well logging tool having transducer means, means for repetitively energizing said transducer means to emit acoustic energy into a media surrounding said well tool, means for rotating said transducer means so that said emitted energy will be sequentially directed at various circumferential portions of a well bore wall, means for producing a transmitted energy signal representative of the time that said energy is emitted, means coupled to said transducer means for producing a first received energy signal representative of that portion of the emitted energy which is returned to said well tool from a well bore wall; acoustic reflector means supported by said tool and positioned between said transducer and a well bore wall for reflecting at least a portion of at least one burst of acoustic energy back to said transducer means to produce a second received energy signal; signal processing means responsive to said sync and first received energy signals for producing an output signal representative of a characteristic of at least part of the media surrounding said well tool; and compensation means responsive to at least said second received energy signal for producing a control signal for use in adjusting a parameter of said signal processing means to compensate said output signal for changes in an acoustic parameter of the fluid in a well bore.

Claim 18

A well logging system comprising: a well logging tool having transducer means, means for repetitively energizing said transducer means to emit acoustic energy into a media surrounding said well tool, means for rotating said transducer means so that said emitted energy will be sequentially directed at various circumferential portions of a well bore wall, means for producing a transmitted energy signal representative of the time that said energy is emitted, means coupled to said transducer means for producing a first received energy signal representative of that portion of the emitted energy which is returned to said well tool from a well bore wall; acoustic reflector means supported by said tool and positioned between said transducer and a well bore wall for reflecting at least a portion of at least one burst of acoustic energy back to said transducer means to produce a second received energy signal; signal processing means responsive to said sync and first received energy signals for producing an output signal representative of a characteristic of at least part of the media surrounding said well tool; and compensation means responsive to at least said second received energy signal for producing a control signal for use in adjusting a parameter of said signal processing means to compensate said output signal for changes in an acoustic parameter of the fluid in a well bore.

Claim 19

The apparatus of claim 14 wherein said compensation means includes first time to amplitude conversion means responsive to the time separation between at least one sync signal and a successive second received energy signal for producing said control signal representative of said time separation; and wherein said signal processing means includes second time to amplitude conversion means responsive to the time separation between successive sync and first received energy signals for producing a signal representative of the distance between said well tool and at least one part of the well bore wall, said control signal operating to vary the transfer characteristic of said second time to amplitude conversion means to thereby compensate for changes in well bore fluid velocity.

Claim 20

The apparatus of claim 14 and further including means responsive to each second received energy signal for preventing said signal processing means from changing the state of said output signal whenever such a second received energy signal is produced, whereby the interception of acoustic energy by said acoustic reflector means will not adversely affect the character of said output signal which is representative of the surrounding media.

Claim 21

The apparatus of claim 15 and further including means responsive to each second received energy signal for preventing said signal processing means from changing the state of said output signal whenever such a second received energy signal is produced whereby the interception of acoustic energy by said acoustic reflector means will not adversely affect the character of said output signal which is representative of the surrounding media.

Claim 22

A well logging system comprising: a well logging tool having transducer means, means for repetitively energizing said transducer mEans to emit acoustic energy into a media surrounding said well tool, means coupled to said transducer means for producing a first received energy signal representative of that portion of the emitted energy which is returned to said well tool from a well bore wall; acoustic reflector means supported by said tool and positioned between said transducer and a borehole wall for reflecting at least a portion of at least one burst of acoustic energy back to said transducer means to produce a second received energy signal; signal processing means responsive to at least said first received energy signal for producing an output signal representative of a characteristic of at least part of the media surrounding said well tool; and means responsive to at least said second received energy signal for adjusting a parameter of said signal processing means to compensate said output signal for changes in an acoustic parameter of the fluid in a borehole.

Claim 23

A well logging system comprising: a well logging tool having transducer means, means for repetitively energizing said transducer mEans to emit acoustic energy into a media surrounding said well tool, means coupled to said transducer means for producing a first received energy signal representative of that portion of the emitted energy which is returned to said well tool from a well bore wall; acoustic reflector means supported by said tool and positioned between said transducer and a borehole wall for reflecting at least a portion of at least one burst of acoustic energy back to said transducer means to produce a second received energy signal; signal processing means responsive to at least said first received energy signal for producing an output signal representative of a characteristic of at least part of the media surrounding said well tool; and means responsive to at least said second received energy signal for adjusting a parameter of said signal processing means to compensate said output signal for changes in an acoustic parameter of the fluid in a borehole.

Claim 30

The method of claim 22 wherein the step of measuring the time separation includes converting the time separation between at least some of said sets of sync and received energy signals to a control signal whose amplitude is representative of said time separation; and wherein the step of adjusting the amplitude of said received energy signals includes varying the amplitude of said received energy signals as a function of the amplitude of said control signal to thereby compensate said received energy signals for variation in well bore cross-section.

Claim 33

The method of claim 23 wherein the step of producing a signal representative of said surrounding media characteristic includes using the amplitudes of at least some of said received energy signals for providing information concerning at least a portion of the media surrounding said well tool; and wherein the step of producing a control signal includes the steps of measuring the amplitude difference between said electrical signals and producing said control signal in proportion to said measured amplitude difference, and using said control signal to adjust the amplitude of at least some of said received energy signals to thereby compensate for variations in the acoustic impedance of the well bore fluid surrounding said well tool.

Claim 34

The method of claim 23 wherein the step of producing a signal representative of said surrounding media characteristic includes the step of measuring the time separation between selected sync and received energy signals for producing measurements representative of the cross-section of a well bore; and wherein the step of producing a control signal includes the steps of measuring the time separation between said electrical signals produced in response to energy received at said two points and producing said control signal in proportion to said measured time separation, and using said control signal to compensate said cross-section measurements for variations in the acoustic velocity of the well bore fluid surrounding said well tool.