PROCESSING OF GEOPHYSICAL DATA

• US 3,689,874 A
• Filed: 11/12/1964
• Issued: 09/05/1972
• Est. Priority Date: 11/12/1964
• Status: Expired due to Term

• Current Assignee: Clyde W. Kerns, 2830 Yorkshire, Manus R. Foster, 1122 S. Edward, Raymond L. Sengbush, 1209 Plattner Drive, Tx, 75050
• Original Assignee: Clyde W. Kerns, 2830 Yorkshire, Manus R. Foster, 1122 S. Edward, Raymond L. Sengbush, 1209 Plattner Drive, Tx, 75050
• Inventors: Manus R. Foster, 1122 S. Edward, Clyde W. Kerns, 2830 Yorkshire, Raymond L. Sengbush, 1209 Plattner Drive, Tx, 75050
• Primary Examiner(s): Benjamin A. Borchelt
• Assistant Examiner(s): N. Moskowitz
• Application Number:
  US04/410,526
• Time in Patent Office: 2,854 Days
• Field of Search: 340/15.5,15.5C,3M,15.5F,15.5CC
• US Class Current: 367/46
• CPC Class Codes: G01V 1/366 by correlation of seismic signals
• CPC Class Codes: G01V 2210/59 Other corrections

Abstract

16. Digital computing apparatus for processing seismograms to compensate for the effect of distortion present in obtaining said seismograms and to emphasize the characteristics of the geological formations producing said seismograms comprising: MEANS FOR CONVERTING SAID SEISMOGRAMS TO ELECTRICAL SIGNALS OF THE TYPE WHICH CAN BE OPERATED UPON BY SAID COMPUTING APPARATUS, A CORRELATOR, SAID ELECTRICAL SIGNALS BEING APPLIED TO SAID CORRELATOR TO PRODUCE AS AN OUTPUT AN ELECTRICAL SIGNAL HAVING A DISTORTION COMPONENT REPRESENTING SAID DISTORTION AND A REFLECTIVITY COMPONENT REPRESENTING SAID CHARACTERISTICS OF SAID GEOLOGICAL FORMATIONS, A SMOOTHING FILTER FOR SMOOTHING THE SPECTRUM OF THE SIGNAL APPLIED TO THE INPUT, THE OUTPUT OF SAID CORRELATOR BEING APPLIED TO SAID SMOOTHING FILTER TO SMOOTH SAID SPECTRUM THEREBY PRODUCING AN OUTPUT REPRESENTING SAID DISTORTION COMPONENT AND SUPPRESSING SAID REFLECTIVITY COMPONENT, AN INVERTER PRODUCING AS AN OUTPUT COEFFICIENTS OF A FILTER HAVING CHARACTERISTICS WHICH ARE THE INVERSE OF THE SIGNAL APPLIED TO THE INPUT OF SAID INVERTER, THE OUTPUT OF SAID SMOOTHING FILTER, REPRESENTING SAID DISTORTION COMPONENT, BEING APPLIED TO SAID INVERTER TO PRODUCE, AS AN OUTPUT OF SAID INVERTER, FILTER COEFFICIENTS WHICH ARE THE INVERSE OF SAID DISTORTION COMPONENT, AN INVERSE FILTER, SAID FILTER COEFFICIENTS BEING APPLIED TO SAID INVERSE FILTER SO THAT SAID INVERSE FILTER HAS FILTERING CHARACTERISTICS WHICH ARE THE INVERSE OF SAID DISTORTION, A FILTER HAVING A BROAD FLAT SIGNAL SPECTRUM IN THE SEISMIC BAND, AND MEANS FOR APPLYING SAID SEISMOGRAMS TO SAID INVERSE FILTER AND TO SAID FILTER HAVING A BROAD FLAT SIGNAL SPECTRUM TO PRODUCE AN OUTPUT EMPHASIZING SAID CHARACTERISTICS OF SAID GEOLOGICAL FORMATIONS.

Claims

1. The method of processing electric signals representing geophysical data to compensate for the effect of distortion present in obtaining said geophysical data and to emphasize the characteristics of the geological formations producing said geophysical data which comprises the following steps each performed in an automatic system:

correlating said electric signals representing geophysical data to obtain an electric signal having a distortion component representing said distortion and having a reflectivity component representing said characteristics of said geological formations, modifying the spectrum of said signal, including smoothing the spectrum of said last-named electric signal, to ensure that the spectrum of the modified signal is non-negative and thereby separating said distortion component from said reflectivity component, inverting said distortion component to produce an inverse distortion filter, and applying said electric signals representing said geophysical data to said inverse distortion filter to produce an output emphasizing said characteristics of said geological formations.

2. The method recited in claim 1 further including the steps of:

selecting a portion of said electric signals representing said geophysical data, and correlating said potion of said electric signals representing said geophysical data to obtain said electric signal having said distortion component and said reflectivity component.

3. The method recited in claim 1 further including the step of:

applying said output of said inverse distortion filter to a further filter which has a broad flat signal spectrum in the seismic band thereby to produce a final output representing the geophysical data which would have been produced in the absence of said distortion.

4. The method of processing geophysical data to compensate for the effect of distortion present in said geophysical data and to emphasize the characteristics of the geological formations producing said geophysical data which comprises in an automatic digital processing system:

selecting a portion of said geophysical data in said system, correlating in said system said portion of said geophysical data to obtain a signal having a distortion component representing said distortion and having a reflectivity component representing said characteristics of said geological formations, truncating said signal to produce spectral smoothing thereby separating said distortion component from said reflectivity component, inverting in said system said distortion component to produce an inverse distortion operator, deriving from said inverse distortion operator an inverse filter, and applying said geophysical data to said inverse filter and to a filter which has a broad flat signal spectrum in the seismic band to produce an output emphasizing said characteristics of said geological formations.

5. The method of processing geophysical data to compensate for the effect of distortion present in obtaining said geophysical data and to emphasize the characteristics of the geological formations producing said geophysical data which comprises in an automatic processing system:

selecting in said system a portion of said geophysical data having a distortion component, producing a signal representing the energy spectrum of said selected geophysical data, convolving said energy spectrum with a smoothing function to produce a signal characterizing the distortion component, inverting in said system said distortion component to produce the inverse of said distortion component, and applying said inverse of said distortion component to said geophysical data to produce an output emphasizing said characteristics of said geological formations.

6. The method of characterizing distortion present in geophysical data representing the characteristics of geological formations which comprises the following steps each performed in an automatic processing system:

selecting a portion of said geophysical data, correlating said portion of said geophysical data to obtain a signal having a distortion component representing said distortion and having a reflectivity component representing said characteristics of said geological formations, and modifying the spectrum of said signal, including truncating said signal, to ensure that the spectrum of the modified signal is non-negative and to produce spectral smoothing thereby separating said distortion component from said reflectivity component.

7. The method of processing geophysical data to suppress distortion present in obtaining said data and to emphasize the characteristics of the geological formations producing said geophysical data whicH comprises in an automatic processing system:

selecting a portion of said geophysical data in said system, autocorrelating in said system said portion of said geophysical data to obtain a signal having a distortion component representing said distortion and having a reflectivity component representing said characteristics of said geological formations, multiplying in said system said signal by a triangular truncator to produce spectral smoothing in said signal thereby to suppress said reflectivity component and to produce an output characterizing said distortion component, determining in said system from said output the coefficients of an optimum, finite memory, inverse filter having characteristics which are the inverse of the distortion operator characterized by said output, deriving from said coefficients an inverse filter having filtering characteristics which are the inverse of said distortion operator, and applying said geophysical data to said inverse filter to produce an output emphasizing said characteristics of said geological formations.

8. The method of processing geophysical data to compensate for the effect of distortion present in said geophysical data and to emphasize the characteristics of the geological formations producing said geophysical data which comprises the following steps each performed in an automatic processing system:

selecting a portion of said geophysical data, correlating said potion of said geophysical data to obtain a signal having a distortion component representing said distortion and having a reflectivity component representing said characteristics of said geological formations, modifying said signal, including truncating said signal, to ensure that the spectrum of the modified signal is non-negative and to produce spectral smoothing thereby separating said distortion component from said reflectivity component, inverting in said system said distortion component to produce an inverse distortion operator, and convolving in said system said geophysical data and said operator to produce an output emphasizing said characteristics of said geological formations.

9. The method of processing geophysical data to emphasize the characteristics representing the geological formations producing said geophysical data which comprises in an automatic digital processing system:

generating from said geophysical data a signal in said system having separable components, smoothing in said system the spectrum of said signal to suppress at least one of said components, inverting in said system the smoothed signal to produce an inverse filter, and applying said geophysical data to said inverse filter and to a filter which has a broad flat signal spectrum in the seismic band to produce an output emphasizing said characteristics of said geological formations.

10. The method of processing geophysical data to emphasize the characteristics representing the geological formations producing said geophysical data which comprises in an automatic processing system:

generating a signal which can be characterized by the autocorrelation function of said geophysical data in said system, modifying the spectrum of said signal, including smoothing said spectrum, to ensure that the spectrum of the modified signal is non-negative, inverting in said system the modified signal to produce an inverse filter, and applying said geophysical data to said inverse filter to produce an output emphasizing said characteristics of said geological formations.

11. The method of processing geophysical data to compensate for the effect of distortion present in obtaining said geophysical data and to emphasize the characteristics representing the geological formations producing said geophysical data which comprises in an automatic digital processing system:

generating in said system from said geophysical data a signal representative of the power spectrum of said geophysical data, said signal having a distortion component representing said distortion and having a reflectivity component representing said characteristics of said geological formations, smoothing in said system the spectrum of said signal thereby separating said distortion component from said reflectivity component, inverting said distortion component to produce an inverse distortion filter, and applying said geophysical data to said inverse distortion filter and to a filter which has a broad flat signal spectrum in the seismic band to produce an output emphasizing said characteristics of said geological formations.

12. The method of characterizing distortion present in geophysical data representing the characteristics of geological formations which comprises the following steps each performed in an automatic processing system:

selecting a portion of said geophysical data, generating from said portion a signal having a distortion component representing said distortion and having a reflectivity component representing said characteristics of said geological formations, and modifying the spectrum of said signal, including smoothing said spectrum, to ensure that the spectrum of the modified signal is non-negative and to separate said distortion component from said reflectivity component.

13. In the processing of geophysical data to compensate for the effect of distortion present in obtaining said geophysical data and to emphasize the characteristics of the geological formations producing said geophysical data, the new use of digital computing apparatus, said computing apparatus being interconnected to include:

a correlator, a smoothing filter for smoothing the spectrum of the signal applied to the input, an inverter producing as an output coefficients of a filter which is the inverse of the signal applied to the input, an inverse filter, and a filter which has a broad flat signal spectrum in the seismic band, said new use comprising;

applying said geophysical data to said correlator to produce as an output a signal having a distortion component representing said distortion and a reflectivity component representing said characteristics of said geological formations, applying said last-named signal to said smoothing filter to smooth the spectrum of said signal thereby separating said distortion component from said reflectivity component, applying the output of said smoothing filter, representing said distortion component, to said inverter to produce as an output of said inverter the coefficients of a filter which is the inverse of said distortion component, applying said coefficients to said inverse filter to provide an inverse filter having filtering which is the inverse of the distortion operator, and applying said geophysical data to said inverse filter and to said filter having a broad flat signal spectrum to produce an output emphasizing said characteristics of said geological formations.

14. The new use recited in claim 13 wherein said smoothing filter includes a multiplier, and wherein said new use includes:

multiplying said geophysical data by a truncator to produce at the output of said multiplier a signal representing said distortion component.

15. The new use recited in claim 13 wherein said smoothing filter includes a convolver and said computing apparatus further includes a Fourier spectrum analyzer, said new use further including:

applying the output of said correlator to said Fourier spectrum analyzer to produce an output indicative of the spectrum of the correlation function, and applying said last-named output to said convolver for convolving said output with a smoothing function to produce at the output of said convolver a signal representing said distortion component.

17. The apparatus recited in claim 16 wherein said smoothing filter includes a multiplier, said seismogram being applied to said multiplier for multiplication by a truncator to produce at the output of said multiplier a signal representing said distortion component.