CA2291333A1 - Noise reduction on geophone data using microphone records - Google Patents
Noise reduction on geophone data using microphone records Download PDFInfo
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- CA2291333A1 CA2291333A1 CA 2291333 CA2291333A CA2291333A1 CA 2291333 A1 CA2291333 A1 CA 2291333A1 CA 2291333 CA2291333 CA 2291333 CA 2291333 A CA2291333 A CA 2291333A CA 2291333 A1 CA2291333 A1 CA 2291333A1
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- CA
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- Prior art keywords
- geophone
- microphone
- signal
- air
- noise
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/28—Processing seismic data, e.g. analysis, for interpretation, for correction
- G01V1/36—Effecting static or dynamic corrections on records, e.g. correcting spread; Correlating seismic signals; Eliminating effects of unwanted energy
- G01V1/364—Seismic filtering
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V2210/00—Details of seismic processing or analysis
- G01V2210/30—Noise handling
- G01V2210/32—Noise reduction
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V2210/00—Details of seismic processing or analysis
- G01V2210/30—Noise handling
- G01V2210/32—Noise reduction
- G01V2210/324—Filtering
- G01V2210/3246—Coherent noise, e.g. spatially coherent or predictable
Abstract
There is proposed use of microphone recordings of air waves, recorded close to a geophone, to suppress air-wave and surface-wave noise on the geophone. The types of air-wave noise on the geophone may include air-coupled ground roll, air blast, ground-coupled air blast and wind noise. Microphone recordings of air waves are related to ground measurements and geophone disturbances. The air wave may be used to filter the geophone data. Tests on recordings from the Calgary General Hospital implosion on October 4, 1998 indicate success in reducing noise on the geophone data. There is further proposed a geophone with an attached microphone to reduce noise on the geophone data.
In addition, a geophone attached to a microphone could be used to reduce ground motion noise on the microphone.
In addition, a geophone attached to a microphone could be used to reduce ground motion noise on the microphone.
Description
s TITLE OF THE INVENTION
Noise Reduction On Geophone Data Using Ivficrophone Records NAME OF INVENTOR
Robert R Stewart io FIELD OF THE INVENTION
This invention relates to seismic recording and signal processing.
BACKGROUND OF THE INVENTION
1 s Air blasts, ground-coupled air waves, and air-coupled ground motions are all potential problems in recording seismic signals. These noises can certainly overwhelm subsurface reflection signals, especially when the noise source is near the receivers. While there are many ways to filter this noise, it still can be a problem, due to spatial aliasing, for example. In addition, winds above a certain speed can create unacceptably high noise 2 0 levels and shut down seismic acquisition operations.
Some ambient noise can be attenuated, in the marine case, by recording pressure (hydrophone) data along with geophone measurements. The hydrophone information is used to suppress fluid-reverberations in the geophone data. Similarly, we can consider suppressing air-associated noise, recorded on a geophone, by use of output from a nearby 2 s microphone.
Air waves travel at the speed of sound in air (about 332 m/s). Airborne noise recording on seismic detectors is known in the art as can be seen in the text by Sheriff and Geldart (1982), Exploration Seismology: History, theory, and data Acquisition, vol. l, Cambridge University Press. If a surface source is used, such as a Poulter charge or land 3 o air gun, the air wave may be significant and problematic (Yilmaz, 1987, Seismic Data Processing, Soc. Explor. Geoph). Vibrators can also generate considerable air disturbances. Ewing et al. (1957), "Elastic Waves in Layered Media, McGraw Hill Book Co." note that air waves can couple into the ground's surface and generate Rayleigh waves.
These occur when the Rayleigh wave phase velocity (for some frequency) is close to the speed of sound in air. In addition, ground roll can also generate an air wave when its velocity is close to that of sound in air as shown by Press and Ewing ( 1951 ), "Ground Roll Coupling to Atmospheric Compressional Waves, GEOPHYSICS." This may be the 1 o source of some reports of a low-frequency rumble, associated with surface wave propagation, after an earthquake occurs as noted by Ewing et al., 1957. Air waves are a problem on near-offset seismic data. In shallow surveys, the ground roll and air waves can overwhelm otherwise usable data.
Winds arise from the pressure differences in the atmosphere. They can be a significant problem in seismic surveying as the wind forces can be translated into geophone motion. This is either directly via wind pressure on the geophone case or through intervening materials that vibrate (e.g., trees, roots, grass, etc). After winds reach a certain velocity, there is too much noise recorded on the geophone to continue effective operation and recording.
SUMMARY OF THE INVENTION
It is an object of this invention to attenuate the various airborne events and surface-wave events registered on seismic recordings. It is a further object of this invention to filter some of this noise so that seismic operations could be extended into more windy 2 s conditions. In addition, ground motion may be attenuated on the microphone data by use of the geophone records.
The inventor has proposed a solution to these problems. There is therefore provided apparatus for processing a seismic signal. The apparatus includes a geophone, having as output a geophone signal, a microphone, having as output a microphone signal;
s o and a circuit in which the geophone and microphone are incorporated, the output of which circuit includes a combination of the microphone signal and the geophone signal that reduces the effect, on the geophone signal, of motion coupled from air to the geophone and s from surface waves.
There is also provided a method of processing a seismic signal, the method comprising the steps of outputting a geophone signal from a geophone, outputting a microphone signal from a microphone located in proximity to the geophone; and combining the microphone signal and the geophone signal to reduce the effect of air 1 o movement on the geophone.
The geophone signal and microphone signal may be delivered separately to a data processor for processing. The geophone signal may be provided in series or parallel with the microphone. In another aspect, the circuit is an active circuit. The microphone signal may be used to modulate, attenuate, or restrict the geophone signal.
1 s Similarly, the geophone signal may be used to filter the microphone signal for undesirable ground noise induced on the microphone reading.
These and other aspects of the invention are described in the detailed description of the invention and claimed in the claims that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
There will now be described preferred embodiments of the invention, with reference to the drawings, by way of illustration only and not with the intention of limiting the scope of the invention, in which like numerals denote like elements and in which:
2 s Fig. 1 is a graph showing raw vertical geophone and microphone traces from a field experiment;
Fig. 2 is a cross-correlation of the microphone trace with the geophone trace of Fig. 1 (the traces are approximately negatively correlated or opposite polarity) ;
Fig. 3 is a summed geophone and microphone traces as function of relative shift;
so and Figs. 4a and 4B show respectively a two channel (microphone and geophone) motion sensor and a single channel active noise suppressing geophone.
DETAILED DESCRIPTION OF PREFERRED EMBODIIVVIENTS
In this patent document, the word "comprising" is used in its non-limiting sense to mean that items following the word in the sentence are included and that items not specifically mentioned are not excluded. The use of the indefinite article "a"
in the claims 1 o before an element means that one of the elements is specified, but does not specifically exclude others of the elements being present, unless, unless the context clearly requires that there be one and only one of the elements.
Air pressure on a microphone is related to ground motion described on a geophone in a number of ways: Air pressure can vibrate the geophone directly or via ground 1 s coupling. Similarly, ground motion can vibrate the air and geophone case and thus the microphone. Ground motion can couple to the air and thus be recorded as pressure on the microphone and motion on the geophone. Fig. 1 shows a comparison between signals recorded by a geophone and microphone located with the geophone that recorded an implosion of a building (described in more detail below). The microphone and vertical 2 o geophone data used here are from the same station and are scaled to the same maximum value. We can see from the raw data that the two traces are similar. In fact, by cross-correlating the data, we find that the traces are about 180° out of phase (Figure 2). To remove the noise as recorded by the microphone then, one procedure is to add the microphone trace to the geophone trace. This procedure leads to a reduction in what we 2 s interpret is the air and air-coupled noise. The summed trace is also shown in Figure 1. We can also shift the traces relative to each other and sum to try to achieve better cancellation.
Figure 3 shows a panel of incremental shifts and sums. Shifts around 0 ms appear to provide (marginally) the greatest noise reduction in the first few seconds.
A NOISE REDUCING MULTI-SENSOR
Two designs for a two-element, air-wave and surface-wave reducing instrument s are described here, though others will occur to those skilled in the art that come within the spirit of the invention. As illustrated in Fig. 4A, one way is to use a microphone 14 in proximity to the geophone 12 and record it separately. Being in proximity means sui~ciently close to the geophone 12 that signals from the microphone 14 are useful to remove air noise and surface-wave noise effects from the geophone 12, as for example 1 o being housed with the geophone 12 in a case 10. The microphone recordings delivered through communications link 18 could be used later to filter the geophone data output from the geophone along communications link 17. Equivalently, sparsely distributed microphones (some distance away from the geophone) could be used with a model-based interpolator to filter intervening geophone data. The microphone recordings delivered at 18 1 s could be recorded separately as a two-channel geophone or with a 3-C
geophone as a four-channel record. The output signals from the microphone 14 and geophone 12 are provided in conventional manner along the communications links 18 and 17 respectively to conventional signal processor 16. In the signal processor 16, known procedures for the combination of two signals may be used to process the output signals from the microphone 2 0 14 and geophone 12. The output from the microphone may be combined with the geophone output to reduce the effect, on the geophone signal, of motion coupled from air to the geophone or ground motion detected by the microphone. Phase and amplitude changes may need to be applied to one signal or the other if any inconsistencies are present in the recordings. The microphone 14 and geophone 12 may both be conventional.
The 2 s arrangement of microphone, geophone and processor forms an electrically connected circuit. The combined geophone and microphone signals may be combined in other ways to remove the effects of air noise or surface-wave noise on the geophone. For example time-varying phasing, exponential scaling of the microphone output, maximum &
minimum value cut-offs, least-squares matching of the signals, match filtering, deterministic 3 o relationships & suppression, principal component analysis & removal, and dispersion analysis, microphone signal deconvolution from the geophone data, and active noise suppression techniques.
s An alten~ative configuration is shown in Fig. 4B, in which is shown a motion sensor that actively reduces noise. In this case, the microphone 14 may be used in a series or parallel circuit with the geophone 12 in a case 20. The air-pressure noise is provided as a resistance to the geophone output in real time simultaneously with the geophone recording. In Fig. 4B, a two-channel sensor is formed by conventional geophone 1 o recording ground movement and an active noise-suppressing sensor is formed by a microphone 14 recording air movement. One channel on link 21 is fed through the microphone 14 in which the signal from the microphone 14 is combined directly with the signal from the geophone 12. Since the signal is passed in real time from the geophone to the microphone, the microphone signal is arranged to modify or restrict the geophone 1 s signal. Various known circuits may be used to effect this. A conventional filter 24 may be used on the output from the microphone. The filter may be for example an adaptive noise filter, feedback filter, or may use neural nets or convolutional filters to assist in removing the microphone signal from the geophone signal. A small battery could be included, if necessary, to power the microphone andlor the electronic circuitry. The signal from the 2 o filter and power supply is combined with the signal fed to the microphone at 22. An arrangement of microphones might also be required to partially decouple the microphone recordings from the geophone case movement. The output from the microphone is fed to signal processor 26, which may fi.uther process the signal in conventional manner.
Note if the geophone and microphone were housed in one case or stand, the 2 s motion of the case or stand may contribute to noise recorded on the microphone. The previous techniques could be used to reduce ground motion noise on the microphone recordings.
FIELD EXAMPLE
3 o The example from which Figs. 1, 2 and 3 were derived is from the implosion of the Calgary General Hospital (Calgary, Alberta, Canada) on Sunday, Oct. 4, 1998.
Seven sites around the hospital, each consisting of a 3-C geophone and microphone plus seismograph, s were used by Explotech Engineering Ltd. with Stanley Buildings to monitor the blast. The microphone (pressure) measurements were made to ensure compliance with explosion-related regulations. These stations varied from 37m to 165m from the blast.
The recordings and their analysis are further discussed in a document prepared by Explotech ( 1998). The data analyzed here are from station #5 at 803 1 st Avenue NE on the 3 rd floor, 1 o some 165m from the blast. The triaxial geophone and microphone both had bandpass responses from 2Hz to 250Hz.
CONCLUSIONS
Air-wave noise and surface-wave ground motion are evident on many seismic records. The use of microphone recordings, in addition to the geophone records, provides i s an opportunity to reduce some of this noise. Tests on the Calgary General Hospital implosion data recorded by Explotech Engineering Ltd., indicate that microphone recordings can be used to reduce air-wave and ground motion noise on geophone measurements A person skilled in the art could make immaterial modifications to the invention 2 o described in this patent document without departing from the essence of the invention that is intended to be covered by the scope of the claims that follow.
Noise Reduction On Geophone Data Using Ivficrophone Records NAME OF INVENTOR
Robert R Stewart io FIELD OF THE INVENTION
This invention relates to seismic recording and signal processing.
BACKGROUND OF THE INVENTION
1 s Air blasts, ground-coupled air waves, and air-coupled ground motions are all potential problems in recording seismic signals. These noises can certainly overwhelm subsurface reflection signals, especially when the noise source is near the receivers. While there are many ways to filter this noise, it still can be a problem, due to spatial aliasing, for example. In addition, winds above a certain speed can create unacceptably high noise 2 0 levels and shut down seismic acquisition operations.
Some ambient noise can be attenuated, in the marine case, by recording pressure (hydrophone) data along with geophone measurements. The hydrophone information is used to suppress fluid-reverberations in the geophone data. Similarly, we can consider suppressing air-associated noise, recorded on a geophone, by use of output from a nearby 2 s microphone.
Air waves travel at the speed of sound in air (about 332 m/s). Airborne noise recording on seismic detectors is known in the art as can be seen in the text by Sheriff and Geldart (1982), Exploration Seismology: History, theory, and data Acquisition, vol. l, Cambridge University Press. If a surface source is used, such as a Poulter charge or land 3 o air gun, the air wave may be significant and problematic (Yilmaz, 1987, Seismic Data Processing, Soc. Explor. Geoph). Vibrators can also generate considerable air disturbances. Ewing et al. (1957), "Elastic Waves in Layered Media, McGraw Hill Book Co." note that air waves can couple into the ground's surface and generate Rayleigh waves.
These occur when the Rayleigh wave phase velocity (for some frequency) is close to the speed of sound in air. In addition, ground roll can also generate an air wave when its velocity is close to that of sound in air as shown by Press and Ewing ( 1951 ), "Ground Roll Coupling to Atmospheric Compressional Waves, GEOPHYSICS." This may be the 1 o source of some reports of a low-frequency rumble, associated with surface wave propagation, after an earthquake occurs as noted by Ewing et al., 1957. Air waves are a problem on near-offset seismic data. In shallow surveys, the ground roll and air waves can overwhelm otherwise usable data.
Winds arise from the pressure differences in the atmosphere. They can be a significant problem in seismic surveying as the wind forces can be translated into geophone motion. This is either directly via wind pressure on the geophone case or through intervening materials that vibrate (e.g., trees, roots, grass, etc). After winds reach a certain velocity, there is too much noise recorded on the geophone to continue effective operation and recording.
SUMMARY OF THE INVENTION
It is an object of this invention to attenuate the various airborne events and surface-wave events registered on seismic recordings. It is a further object of this invention to filter some of this noise so that seismic operations could be extended into more windy 2 s conditions. In addition, ground motion may be attenuated on the microphone data by use of the geophone records.
The inventor has proposed a solution to these problems. There is therefore provided apparatus for processing a seismic signal. The apparatus includes a geophone, having as output a geophone signal, a microphone, having as output a microphone signal;
s o and a circuit in which the geophone and microphone are incorporated, the output of which circuit includes a combination of the microphone signal and the geophone signal that reduces the effect, on the geophone signal, of motion coupled from air to the geophone and s from surface waves.
There is also provided a method of processing a seismic signal, the method comprising the steps of outputting a geophone signal from a geophone, outputting a microphone signal from a microphone located in proximity to the geophone; and combining the microphone signal and the geophone signal to reduce the effect of air 1 o movement on the geophone.
The geophone signal and microphone signal may be delivered separately to a data processor for processing. The geophone signal may be provided in series or parallel with the microphone. In another aspect, the circuit is an active circuit. The microphone signal may be used to modulate, attenuate, or restrict the geophone signal.
1 s Similarly, the geophone signal may be used to filter the microphone signal for undesirable ground noise induced on the microphone reading.
These and other aspects of the invention are described in the detailed description of the invention and claimed in the claims that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
There will now be described preferred embodiments of the invention, with reference to the drawings, by way of illustration only and not with the intention of limiting the scope of the invention, in which like numerals denote like elements and in which:
2 s Fig. 1 is a graph showing raw vertical geophone and microphone traces from a field experiment;
Fig. 2 is a cross-correlation of the microphone trace with the geophone trace of Fig. 1 (the traces are approximately negatively correlated or opposite polarity) ;
Fig. 3 is a summed geophone and microphone traces as function of relative shift;
so and Figs. 4a and 4B show respectively a two channel (microphone and geophone) motion sensor and a single channel active noise suppressing geophone.
DETAILED DESCRIPTION OF PREFERRED EMBODIIVVIENTS
In this patent document, the word "comprising" is used in its non-limiting sense to mean that items following the word in the sentence are included and that items not specifically mentioned are not excluded. The use of the indefinite article "a"
in the claims 1 o before an element means that one of the elements is specified, but does not specifically exclude others of the elements being present, unless, unless the context clearly requires that there be one and only one of the elements.
Air pressure on a microphone is related to ground motion described on a geophone in a number of ways: Air pressure can vibrate the geophone directly or via ground 1 s coupling. Similarly, ground motion can vibrate the air and geophone case and thus the microphone. Ground motion can couple to the air and thus be recorded as pressure on the microphone and motion on the geophone. Fig. 1 shows a comparison between signals recorded by a geophone and microphone located with the geophone that recorded an implosion of a building (described in more detail below). The microphone and vertical 2 o geophone data used here are from the same station and are scaled to the same maximum value. We can see from the raw data that the two traces are similar. In fact, by cross-correlating the data, we find that the traces are about 180° out of phase (Figure 2). To remove the noise as recorded by the microphone then, one procedure is to add the microphone trace to the geophone trace. This procedure leads to a reduction in what we 2 s interpret is the air and air-coupled noise. The summed trace is also shown in Figure 1. We can also shift the traces relative to each other and sum to try to achieve better cancellation.
Figure 3 shows a panel of incremental shifts and sums. Shifts around 0 ms appear to provide (marginally) the greatest noise reduction in the first few seconds.
A NOISE REDUCING MULTI-SENSOR
Two designs for a two-element, air-wave and surface-wave reducing instrument s are described here, though others will occur to those skilled in the art that come within the spirit of the invention. As illustrated in Fig. 4A, one way is to use a microphone 14 in proximity to the geophone 12 and record it separately. Being in proximity means sui~ciently close to the geophone 12 that signals from the microphone 14 are useful to remove air noise and surface-wave noise effects from the geophone 12, as for example 1 o being housed with the geophone 12 in a case 10. The microphone recordings delivered through communications link 18 could be used later to filter the geophone data output from the geophone along communications link 17. Equivalently, sparsely distributed microphones (some distance away from the geophone) could be used with a model-based interpolator to filter intervening geophone data. The microphone recordings delivered at 18 1 s could be recorded separately as a two-channel geophone or with a 3-C
geophone as a four-channel record. The output signals from the microphone 14 and geophone 12 are provided in conventional manner along the communications links 18 and 17 respectively to conventional signal processor 16. In the signal processor 16, known procedures for the combination of two signals may be used to process the output signals from the microphone 2 0 14 and geophone 12. The output from the microphone may be combined with the geophone output to reduce the effect, on the geophone signal, of motion coupled from air to the geophone or ground motion detected by the microphone. Phase and amplitude changes may need to be applied to one signal or the other if any inconsistencies are present in the recordings. The microphone 14 and geophone 12 may both be conventional.
The 2 s arrangement of microphone, geophone and processor forms an electrically connected circuit. The combined geophone and microphone signals may be combined in other ways to remove the effects of air noise or surface-wave noise on the geophone. For example time-varying phasing, exponential scaling of the microphone output, maximum &
minimum value cut-offs, least-squares matching of the signals, match filtering, deterministic 3 o relationships & suppression, principal component analysis & removal, and dispersion analysis, microphone signal deconvolution from the geophone data, and active noise suppression techniques.
s An alten~ative configuration is shown in Fig. 4B, in which is shown a motion sensor that actively reduces noise. In this case, the microphone 14 may be used in a series or parallel circuit with the geophone 12 in a case 20. The air-pressure noise is provided as a resistance to the geophone output in real time simultaneously with the geophone recording. In Fig. 4B, a two-channel sensor is formed by conventional geophone 1 o recording ground movement and an active noise-suppressing sensor is formed by a microphone 14 recording air movement. One channel on link 21 is fed through the microphone 14 in which the signal from the microphone 14 is combined directly with the signal from the geophone 12. Since the signal is passed in real time from the geophone to the microphone, the microphone signal is arranged to modify or restrict the geophone 1 s signal. Various known circuits may be used to effect this. A conventional filter 24 may be used on the output from the microphone. The filter may be for example an adaptive noise filter, feedback filter, or may use neural nets or convolutional filters to assist in removing the microphone signal from the geophone signal. A small battery could be included, if necessary, to power the microphone andlor the electronic circuitry. The signal from the 2 o filter and power supply is combined with the signal fed to the microphone at 22. An arrangement of microphones might also be required to partially decouple the microphone recordings from the geophone case movement. The output from the microphone is fed to signal processor 26, which may fi.uther process the signal in conventional manner.
Note if the geophone and microphone were housed in one case or stand, the 2 s motion of the case or stand may contribute to noise recorded on the microphone. The previous techniques could be used to reduce ground motion noise on the microphone recordings.
FIELD EXAMPLE
3 o The example from which Figs. 1, 2 and 3 were derived is from the implosion of the Calgary General Hospital (Calgary, Alberta, Canada) on Sunday, Oct. 4, 1998.
Seven sites around the hospital, each consisting of a 3-C geophone and microphone plus seismograph, s were used by Explotech Engineering Ltd. with Stanley Buildings to monitor the blast. The microphone (pressure) measurements were made to ensure compliance with explosion-related regulations. These stations varied from 37m to 165m from the blast.
The recordings and their analysis are further discussed in a document prepared by Explotech ( 1998). The data analyzed here are from station #5 at 803 1 st Avenue NE on the 3 rd floor, 1 o some 165m from the blast. The triaxial geophone and microphone both had bandpass responses from 2Hz to 250Hz.
CONCLUSIONS
Air-wave noise and surface-wave ground motion are evident on many seismic records. The use of microphone recordings, in addition to the geophone records, provides i s an opportunity to reduce some of this noise. Tests on the Calgary General Hospital implosion data recorded by Explotech Engineering Ltd., indicate that microphone recordings can be used to reduce air-wave and ground motion noise on geophone measurements A person skilled in the art could make immaterial modifications to the invention 2 o described in this patent document without departing from the essence of the invention that is intended to be covered by the scope of the claims that follow.
Claims (16)
1. Apparatus for processing a seismic signal, the apparatus comprising:
a geophone, which records ground movement and has as output a geophone signal;
a microphone, which records air pressures and noise and has as output a microphone signal; and a circuit in which the geophone and microphone are incorporated, the output of which circuit includes a combination of the microphone signal and the geophone signal that reduces the effect, on the geophone signal, of motion coupled from air to the geophone.
a geophone, which records ground movement and has as output a geophone signal;
a microphone, which records air pressures and noise and has as output a microphone signal; and a circuit in which the geophone and microphone are incorporated, the output of which circuit includes a combination of the microphone signal and the geophone signal that reduces the effect, on the geophone signal, of motion coupled from air to the geophone.
2. The apparatus of claim 1 in which the geophone signal and microphone signal are delivered separately to a data processor for processing.
3. The apparatus of claim 1 in which the geophone signal is provided in series or parallel with the microphone.
4. The apparatus of claim 3 in which the circuit is an active circuit.
5. A method of processing a seismic signal, the method comprising the steps of outputting a geophone signal from a geophone that is responsive to ground movement;
outputting a microphone signal from a microphone that is responsive to air movement; and combining the microphone signal and the geophone signal to reduce the effect of air movement on the geophone.
outputting a microphone signal from a microphone that is responsive to air movement; and combining the microphone signal and the geophone signal to reduce the effect of air movement on the geophone.
6. The method of claim 5 in which the geophone signal and microphone signal are delivered separately to a data processor for processing.
7. The method of claim 5 in which the geophone signal is provided in series or parallel with the microphone.
8. The method of claim 7 in which the circuit is an active circuit.
9. A method of processing a seismic signal, the method comprising the steps of outputting a geophone signal from a geophone that is responsive to ground movement, including surface-wave motion;
outputting a microphone signal from a microphone that is responsive to air movement; and combining the microphone signal and the geophone signal to reduce the effect of surface-wave movement on the geophone.
outputting a microphone signal from a microphone that is responsive to air movement; and combining the microphone signal and the geophone signal to reduce the effect of surface-wave movement on the geophone.
10. The method of claim 9 in which the geophone signal and microphone signal are delivered separately to a data processor for processing.
11. The method of claim 9 in which the geophone signal is provided in series or parallel with the microphone.
12. The method of claim 11 in which the circuit is an active circuit.
13. A method of processing a microphone signal, the method comprising the steps of outputting a geophone signal from a geophone that is responsive to ground movement, including surface-wave motion;
outputting a microphone signal from a microphone that is responsive to air movement; and combining the microphone signal and the geophone signal to reduce the effect ground motion and surface-wave movement on the microphone.
outputting a microphone signal from a microphone that is responsive to air movement; and combining the microphone signal and the geophone signal to reduce the effect ground motion and surface-wave movement on the microphone.
14. The method of claim 13 in which the geophone signal and microphone signal are delivered separately to a data processor for processing.
15. The method of claim 13 in which the geophone signal is provided in series or parallel with the microphone.
16. The method of claim 15 in which the circuit is an active circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2291333 CA2291333A1 (en) | 1999-11-30 | 1999-11-30 | Noise reduction on geophone data using microphone records |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2291333 CA2291333A1 (en) | 1999-11-30 | 1999-11-30 | Noise reduction on geophone data using microphone records |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2291333A1 true CA2291333A1 (en) | 2001-05-30 |
Family
ID=4164762
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2291333 Abandoned CA2291333A1 (en) | 1999-11-30 | 1999-11-30 | Noise reduction on geophone data using microphone records |
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|---|---|
| CA (1) | CA2291333A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009051883A1 (en) * | 2007-10-19 | 2009-04-23 | Westerngeco L.L.C. | Testing a sensor to produce a filter for noise attenuation |
-
1999
- 1999-11-30 CA CA 2291333 patent/CA2291333A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009051883A1 (en) * | 2007-10-19 | 2009-04-23 | Westerngeco L.L.C. | Testing a sensor to produce a filter for noise attenuation |
| US8077541B2 (en) | 2007-10-19 | 2011-12-13 | Westerngeco L.L.C. | Testing a sensor to produce a filter for noise attenuation |
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