Methods and apparatus for applying surface consistent phase-dependent phase corrections

Patent metadata

Field	Value
Publication number	US-10345471-B2
Application number	US-201515110833-A
Country	US
Kind code	B2
Filing date	Jan 13, 2015
Priority date	Jan 13, 2014
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

Methods and apparatuses compute and apply surface-consistent frequency-dependent phase corrections, to traces extracted from seismic survey data, using a multi-scale iterative approach.

First claim

What is claimed is:

1. A method applying surface consistent phase corrections to a group of traces extracted from seismic survey data, the method comprising:
receiving seismic survey data acquired over a subsurface;
computing frequency dependent phase filters associated with frequency windows, for traces extracted from the seismic survey data and corresponding to a shot or to a receiver, the frequency dependent phase filters being computed using at least one reference trace that is substantially free of phase shifts, and using overlapping frequency windows with different bandwidths for at least one frequency range;
applying the computed phase filters to the traces, and
recovering structural information related to the subsurface from the filtered traces
wherein the method further comprises:
as long as an energy difference between energy of the traces after applying the phase filters and energy of the traces before applying the phase filters exceeds a first threshold, repeatedly perform using same frequency windows spanning a frequency range;
updating the at least one reference trace based on the traces after applying the phase filters, and
performing the computing of the frequency dependent phase filters and the applying of the computed phase filters to the traces;

changing a width the frequency windows to obtain new frequency windows, when the energy difference no longer exceeds the first threshold; and
performing the computing of the frequency dependent filters for the new frequency windows, the applying of the computed phase filters, and the updating of the reference trace, as long as the energy difference exceeds a second threshold,
wherein a phase correction for a frequency sub-range included in one of the frequency windows and in one of the new frequency windows is a sum of a first phase correction corresponding to the phase filters computed for the one of the frequency windows and a second phase correction corresponding to the phase filters computed for the one of the new frequency windows.

2. The method of claim 1 , wherein, if a trace in the group of traces is part of a Common Mid-Point Stack, CMS, then an average CMS trace is used as the at least one reference trace.

3. The method of claim 1 , wherein the frequency dependent phase filters are based on phase differences obtained from a frequency domain normalized cross-spectrum of the traces corresponding to the shot or to the receiver, and the at least one reference trace.

4. The method of claim 3 , wherein the frequency dependent phase filters are based on an average of the phase differences obtained for at least two different temporal blocks.

5. The method of claim 1 , wherein the computing of the frequency dependent filters, and the applying of the computed phase filters, are performed for plural shots and/or receivers.

6. The method of claim 1 , wherein the second threshold is equal to the first threshold and the changed width is smaller than the width.

7. The method of claim 1 , wherein, when the width is changed, the second threshold is determined using a predetermined threshold rule and/or the changed width is determined using a predetermined width changing rule.

8. The method of claim 1 , wherein the changed width and/or the second threshold are determined from a predetermined list of widths and/or threshold values.

9. The method of claim 1 , further comprising:
applying a method for static corrections before performing the computing of the frequency dependent phase filters for the first time.

10. An apparatus configured to apply surface consistent phase corrections to traces extracted from seismic survey data, the apparatus comprising:
an interface configured
to receive the seismic survey data acquired over a surveyed formation, and
to output or store the seismic survey data after the surface consistent phase corrections are applied, for further processing leading to an image of the surveyed formation; and

a data processing unit including at least one processor and configured
to compute frequency dependent phase filters associated with frequency windows, for traces extracted from the seismic survey data and corresponding to a shot point or to a receiver, the frequency dependent phase filters being computed using at least one reference trace that is substantially free of phase anomalies, and using overlapping frequency windows with different bandwidths for at least one frequency range, and
to apply the computed phase filters to the traces

wherein the data processing unit is further configured to perform repeatedly:
as long as a power difference between power of the traces before applying the computed phase filters and power of the traces after applying the computed phase filters exceeds a first threshold:
updating the at least one reference trace using the traces after applying the phase filters, and
computing the frequency dependent phase filters and apply the computed phase filters to the traces; and

the data processing unit is further configured to change the width of the frequency windows, when the power difference no longer exceeds the first threshold, and then to compute the frequency dependent filters associated with frequency windows having the changed width, apply the computed phase filters, and update the reference trace, as long as the power difference exceeds a second threshold.

11. The apparatus of claim 10 , wherein if a trace in the group of traces is part of a Common Mid-Point Stack, CMS, then an average CMS trace is used as the at least one reference trace.

12. The apparatus of claim 10 , wherein the data processing unit computes the frequency dependent phase filters based on phase differences obtained using a frequency domain normalized cross-spectrum of the traces corresponding to the shot or to the receiver, and the at least one reference trace, and/or the data processing unit averages the phase differences obtained using at least two different temporal blocks.

13. The apparatus of claim 10 , wherein the data processing unit is further configured to compute the frequency dependent filters, and to apply the computed phase filters for plural shots and/or receivers.

14. The apparatus of claim 10 , wherein the data processing unit is further configured:
to determine the second threshold using a predetermined threshold rule and/or the changed width using a predetermined width changing rule, or
to determine the changed width and/or the second threshold from a predetermined list of width and/or threshold values.

15. The apparatus of claim 10 , wherein the data processing unit is further configured to apply a method for static corrections before computing of the frequency dependent phase filters.

16. A non-transitory computer readable recoding medium storing executable codes which, when executed by a computer, make the computer to perform a method for applying surface consistent frequency dependent phase corrections to traces extracted from seismic survey data, the method comprising:
receiving seismic survey data acquired over a subsurface;
computing frequency dependent phase filters associated with frequency windows, for traces extracted from the seismic survey data and corresponding to a shot or to a receiver, the frequency dependent phase filters being computed using at least one reference trace that is substantially free of phase shifts, and using overlapping frequency windows with different bandwidths for at least one frequency range;
applying the computed phase filters to the traces; and
recovering structural information related to the subsurface from the filtered traces wherein

Assignees

• Cgg Services Sa

Inventors

• Garceran Katia

Classifications

• G01V1/364 Primary

  Seismic filtering (G01V1/37 takes precedence) · CPC title

• G01V2210/582

  Dispersion · CPC title

• G01V1/366 Primary

  by correlation of seismic signals · CPC title