GAPPED DECONVOLUTION REVERBERATION REMOVAL

• US 3,629,800 A
• Filed: 09/18/1969
• Issued: 12/21/1971
• Est. Priority Date: 09/18/1969
• Status: Expired due to Term

• Current Assignee: Halliburton Company
• Original Assignee: William A. Schneider
• Inventors: Schneider, William A.
• Application Number:
  US04/859,002
• Time in Patent Office: 824 Days
• US Class Current: 367/24
• CPC Class Codes: G01V 1/366 by correlation of seismic signals
• CPC Class Codes: G01V 2210/56 De-ghosting; Reverberation compensation
• CPC Class Codes: H03H 17/02 Frequency selective networks digital computers for complex mathematical operations G06F17/10

Abstract

Disclosed is a method of suppressing reverberatory energy in a seismic trace by subtracting from said trace a trace synthesized by time domain filtering said seismic trace, delayed by time, T, approximately equal to the two-way travel time of seismic energy in the reverberating medium, said filter parameters being defined by the matrix equation Ym (X) 1Z where Z is the crosscorrelation coefficient function of a portion of the seismic trace within a truncated data gate and characterized by the reverberation energy, and a similar portion of the seismic trace delayed by a time T; X is the autocorrelation coefficient function of that portion of the trace and Ym is the function designing filter weights.

Claims

1. The method of reverberation suppression in marine seismic exploration which comprises:

a. generating and detecting seismic waves in a surface water layer to produce an electrical seismic trace which includes manifestations of a primary reflection, b. generating by machine means an electrical autocorrelation function X over a selected truncated data gate of said trace for a plurality of delay intervals, c. generating by machine means an electrical crosscorrelation function Z for said plurality of delay intervals between i. said truncated data gate of said seismic trace, and ii. the same truncated data gate delayed a time interval of the order of the two-way travel time in said water layer over a data gate which includes reverberation energy in said trace, d. time domain filtering by machine means said trace with relative amplitudes proportional to (Ym) in the matrix X(Ym) Z, e. delaying by machine means the filtered trace relative to said seismic trace by a time interval T, and f. subtracting by machine means the filtered and delayed trace from said seismic trace to suppress reverberations of said primary reflection.

2. The method of reverberation suppression in marine seismic exploration which comprises:

a. generating and detecting seismic waves in a surface water layer to produce an electrical seismic trace which includes manifestations of a primary reflection, and b. causing an automatically operable system to perform the steps of i. generating an autocorrelation function X over a selected truncated data gate of said trace for a plurality of delay intervals, ii. generating an electrical crosscorrelation function Z for said plurality of delay intervals between said truncated data gate of said seismic trace, and the same truncated data gate delayed a time interval of the order of the two-way travel time in said water layer over a data gate which includes reverberation energy in said trace, iii. time domain filtering said trace with relative amplitudes proportional to (Ym) in the matrix X(Ym) Z, iv. delaying the filtered trace relative to said seismic trace by a time interval T, and v. subtracting the filtered and delayed trace from said seismic trace to suppress reverberations of said primary reflection.

3. The method of reverberation suppression in marine seismic exploration which comprises:

a. generating and detecting seismic waves in a surface water layer to produce an electrical seismic trace which includes manifestations of a primary reflection, and b. operating an automatic data processing machine to perform the steps of i. generating an electrical autocorrelation function X over a selected truncated data gate of said trace for a plurality of delay intervals, ii. generating an electrical crosscorrelation function Z for said plurality of delay intervals between said truncated data gate of said seismic trace, and the same truncated data gate delayed a time interval of the order of the two-way travel time in said water layer over a data gate which includes reverberation energy in said trace, iii. time domain filtering said trace with relative amplitudes proportional to (Ym) in the matrix X(Ym) Z, iv. delaying the filtered trace relative to said seismic trace by a time interval T, and v. subtracting the filtered and delayed trace from said seismic trace to suppress reverberations of said primary reflection.

4. The method according to claim 3 in which said truncated data gate is rampEd from zero to unity at the onset and from unity to zero at its termination within predetermined time intervals.

5. The combination set forth in claim 4 wherein said ramped onset and termination extends for about 20 percent of the length of said data gate.

6. The system for reverberation suppression in marine seismic exploration which comprises:

a. means for generating and detecting seismic waves in a surface water layer to produce an electrical seismic trace which includes manifestations of a primary reflection, b. machine means for generating an autocorrelation function X over a selected truncated data gate of said trace for a plurality of delay intervals, c. machine means for generating a crosscorrelation function Z for said plurality of delay intervals between said truncated data gate of said seismic trace, and the same truncated data gate delayed a time interval of the order of the two-way travel time in said water layer over a data gate which includes reverberation energy in said trace, d. machine means for time domain filtering said trace with relative amplitudes proportional to (Ym) in the matrix X(Ym) Z, e. machine means for delaying the filtered trace relative to said seismic trace by a time interval T, and f. machine means for subtracting the filtered and delayed trace from said seismic trace to suppress reverberations of said primary reflection.

7. The system as set forth in claim 6 wherein each of said machine means is automatically operable.

8. The method of suppressing reverberation energy in marine seismic exploration which comprises:

a. generating seismic waves in a surface water layer at a sending station and receiving the seismic waves at a receiving station spaced from said sending station, b. generating and storing an electrical seismic trace representative of the received seismic waves in at least two independently reproducible forms, c. generating by machine means a plurality of electrical autocorrelation coefficients X for a first truncated data gate of said seismic trace characterized by the presence of reverberation energy for a plurality of incremental time delays from minus Tau n to plus Tau n where n is an integer, d. generating by machine means a plurality of electrical crosscorrelation coefficients between said first data gate and a second similar data gate a time T later in said trace where T is about the travel time of seismic energy from said sending station to the water bottom and back to said receiving station, e. reproducing and time domain filtering by machine means said seismic trace in accordance with a cross-equalization filter (Ym) as defined by the matrix (Ym) (X) 1Z, and f. reproducing said seismic trace and subtracting from it by machine means said filtered trace delayed by a time T relative to said seismic trace to produce an electrical seismic trace wherein reverberation energy is suppressed.

9. The method of suppressing reverberation energy in marine seismic exploration which comprises:

a. generating seismic waves in a surface water layer at a sending station and receiving the seismic waves at a receiving station spaced from said sending station, b. generating and storing an electrical seismic trace representative of the received seismic waves in at least two independently reproducible forms, and c. causing an automatically operable system to perform the steps of i. generating a plurality of electrical autocorrelation coefficients X for a first truncated data gate of said seismic trace characterized by the presence of reverberation energy for a plurality of incremental time delays from minus Tau n to plus n where n is an integer, ii. generating a plurality of electrical crosscorrelation coefficients between said first data gate and a second similar data gate a tIme T later in said trace where T is about the travel time of seismic energy from said sending station to the water bottom and back to said receiving station, iii. reproducing and time domain filtering said seismic trace in accordance with a cross-equalization filter (Ym) as defined by the matrix (Ym) (X) 1Z, and iv. reproducing said seismic trace and subtracting from it said filtered trace delayed by a time T relative to said seismic trace to produce an electrical seismic trace wherein reverberation energy is suppressed.

10. A system for suppressing reverberation energy in marine seismic exploration which comprises:

a. means for generating seismic waves in a surface water layer at a sending station and receiving the seismic waves at a receiving station spaced from said sending station, b. means for generating and storing an electrical seismic trace representative of the received seismic waves in at least two independently reproducible forms, c. means for generating a plurality of electrical autocorrelation coefficients X for a first truncated data gate of said seismic trace characterized by the presence of reverberation energy for a plurality of incremental time delays from minus Tau n to plus n where n is an integer, d. means for generating a plurality of electrical crosscorrelation coefficients between said first data gate and a second similar data gate a time T later in said trace where T is about the travel time of seismic energy from said sending station to the water bottom and back to said receiving station, e. means for reproducing and time domain filtering said seismic trace in accordance with a cross-equalization filter (Ym) as defined by the matrix (Ym) (X) 1Z, and f. means for reproducing said seismic trace and subtracting from it said filtered trace delayed by a time T relative to said seismic trace to produce an electrical seismic trace wherein reverberation energy is suppressed.

11. The method of time domain filtering by automatic machine means an electrical seismic trace representing seismic motion at a marine receiving station following creation of a seismic disturbance at a marine sending station which comprises:

a. reproducing said trace on a plurality of channels with uniform delays therebetween where said time delays are positive and negative relative to an intermediate one of said channels, b. weighting the output of each of said channels and summing said outputs to produce a sum trace, said weightings having relative values corresponding with the cross-equalization filter relating a truncated data gate of said seismic trace characterized by the presence of reverberation energy to a similar truncated data gate of said seismic trace later in time by about T the travel time of seismic energy from said sending station to the water bottom and back to said receiving station, c. reproducing said seismic trace, d. reproducing said sum trace delayed relative to said seismic trace by a time T, and e. subtracting said delayed sum trace from said seismic trace to produce a trace wherein reverberations of primary reflections present in said seismic trace are suppressed.

12. A system for time domain filtering an electrical seismic trace representing seismic motion at a marine receiving station following creation of a seismic disturbance at a marine sending station which comprises:

a. means for reproducing said trace on a plurality of channels with uniform delays therebetween where said time delays are positive and negative relative to an intermediate one of said channels, b. means for weighting the output of each of said channels and summing said outputs to produce a sum trace, said weightings having relative values corresponding with the cross-equalization filter relating a truncated data gate of said seismic trace characterized by the presence of reverberation energy to a similar truncated data gate of said seismic trace later in time by about T the travel time of seismic energy from said sending station to the water bottom and back to said receiving station, c. means for reproducing said seismic trace, d. means for reproducing said sum trace delayed relative to said seismic trace by a time T, and e. means for subtracting said delayed sum trace from said seismic trace to produce a trace wherein reverberations of primary reflections present in said seismic trace are suppressed.