Methods and systems to separate seismic data associated with impulsive and non-impulsive sources

Patent metadata

Field	Value
Publication number	US-11378706-B2
Application number	US-201816134235-A
Country	US
Kind code	B2
Filing date	Sep 18, 2018
Priority date	Oct 20, 2014
Publication date	Jul 5, 2022
Grant date	Jul 5, 2022

Abstract

Methods and systems to separate seismic data associated with impulsive and non-impulsive sources are described. The impulsive and non-impulsive sources may be towed through a body of water by separate survey vessels. Receivers of one or more streamers towed through the body of water above a subterranean formation generate seismic data that represents a reflected wavefield produced by the subterranean formation in response to separate source wavefields generated by simultaneous activation of the impulsive source and the non-impulsive source. Methods and systems include separating the seismic data into impulsive source seismic data associated with the impulsive source and non-impulsive source seismic data associated with the non-impulsive.

First claim

The invention claimed is:

1. A method to survey a subterranean formation, the method comprising:
activating an impulsive source above the subterranean formation to generate an impulsive source wavefield having an impulsive source band of frequencies;
simultaneously activating a non-impulsive source above the subterranean formation to generate a non-impulsive source wavefield having a non-impulsive source band of frequencies that overlap the impulsive source band of frequencies;
recording seismic data generated by a receiver, the seismic data represents the response of the subterranean formation to the impulsive and non-impulsive source wavefields; and
separating the seismic data into impulsive source seismic data and non-impulsive source seismic data over the overlap band of frequencies.

2. The method of claim 1 , wherein separating the seismic data further comprises:
recording a near-field signature of each impulsive source element of the impulsive source and a near-field signature of each non-impulsive source element of the non-impulsive source;
determining an impulsive source far-field signature of the impulsive source at a location of the receiver based on the near-field signatures of the impulsive source elements and a non-impulsive source far-field signature of the non-impulsive source at the location of the receiver based on the near-field signatures of the non-impulsive source elements; and
separating the seismic data into impulsive source seismic data and non-impulsive source seismic data based on one of the impulsive source far-field signature and the non-impulsive source far-field signature.

3. The method of claim 2 , wherein the near-field signature of each impulsive source element of the impulsive source further comprises a pressure wavefield measured by a pressure sensor located within the near field of each impulsive source element of the impulsive source.

4. The method of claim 2 , wherein the near-field signature of each non-impulsive source element of the non-impulsive source further comprises a pressure wavefield measured by a pressure sensor located within the near field of each non-impulsive source element of the non-impulsive source.

5. The method of claim 2 , wherein determine the impulsive and non-impulsive source far-field signatures further comprises:
computing a notional signature for each impulsive source element of the impulsive source, based on the near-field signatures of the impulsive source elements;
computing an impulsive source far-field signature of the impulsive source based on the notional signatures of each impulsive source element;
computing a notional signature for each non-impulsive source element of the non-impulsive source, based on the near-field signatures of the non-impulsive source elements; and
computing a non-impulsive source far-field signature of the non-impulsive source based on the notional signatures of each non-impulsive source element.

6. The method of claim 1 , further comprising time compressing the non-impulsive source seismic data.

7. The method of claim 1 , wherein simultaneously activating the non-impulsive source further comprises continuously activating the non-impulsive source.

8. The method of claim 1 , further comprises:
computing a time-compression filter based on the non-impulsive far-field signature; and
applying the time-compression filter to the non-impulsive seismic data to generate time-compressed non-impulsive seismic data.

9. The method of claim 1 , wherein separating the seismic data into impulsive source seismic data and non-impulsive source seismic data further comprises separating the seismic data in an overlap band of frequencies between impulsive source band of frequencies and a non-impulsive source band of frequencies.

10. The method of claim 1 , wherein the impulsive source seismic data having an associated impulsive source band of frequencies and the non-impulsive source seismic data having an associated impulsive source band of frequencies that overlaps the impulsive source band of frequencies.

11. The method of claim 1 , further comprising:
towing the impulsive source in front of the receiver; and
towing the non-impulsive source behind the receiver to create destructive interference between the impulsive and non-impulsive source wavefields at a location of the receiver.

12. The method of claim 1 , further comprising:
towing the non-impulsive source in front of the receiver; and
towing the impulsive source behind the receiver to create destructive interference between the impulsive and non-impulsive source wavefields at a location of the receiver.

13. The method of claim 1 , wherein activating in the impulsive source further comprises activating the impulsive source with a random time delay between activations.

14. The method of claim 1 , further comprises generating a geophysical data product from the impulsive source seismic data and the non-impulsive source seismic data.

15. The method of claim 1 , further comprises storing the impulsive source seismic data and non-impulsive source seismic data in a data-storage device.

Assignees

• Pgs Geophysical As

Inventors

• Lunde Nils
• Orji Okwudili Chuks
• Oscarsson Mattias Dan Christian

Classifications

• G01V1/36 Primary

  Effecting static or dynamic corrections on records, e.g. correcting spread; Correlating seismic signals; Eliminating effects of unwanted energy · CPC title

• G01V1/366 Primary

  by correlation of seismic signals · CPC title

• G01V2210/20

  Trace signal pre-filtering to select, remove or transform specific events or signal components, i.e. trace-in/trace-out · CPC title

• G01V2210/127

  Cooperating multiple sources · CPC title

• G01V2210/1212

  Shot · CPC title