Full-waveform inversion with elastic mitigation using acoustic anisotropy

Patent metadata

Field	Value
Publication number	US-12320937-B2
Application number	US-202217734322-A
Country	US
Kind code	B2
Filing date	May 2, 2022
Priority date	May 2, 2022
Publication date	Jun 3, 2025
Grant date	Jun 3, 2025

Abstract

Seismic data is processed using a full-waveform inversion using a model with a pseudo-δ layer. The presence of the pseudo-δ layer in the model enables handing the difference at the water bottom between acoustically generated synthetic data and seismic data that corresponds to an elastic medium. The pseudo-δ layer may be less than 100 m thick and/or may be located directly underneath the water bottom. The pseudo-δ layer may have a negative value for S and a null value for ϵ (δ and ϵ being Thomsen's anisotropy parameters).

First claim

What is claimed is:

1. A seismic exploration method, the method comprising:
obtaining seismic data acquired over an underground formation covered by a water layer;
performing a full-waveform inversion, FWI, of the seismic data using a model with a pseudo-δ layer located directly underneath the water layer to generate synthetic data, the FWI updating the model to minimize differences between the seismic data and the synthetic data; and
locating sought-after natural resources in the underground formation using the model of the underground formation updated by the FWI.

2. The method of claim 1 , wherein the pseudo-δ layer is less than 100 m thick.

3. The method of claim 1 , wherein the pseudo-δ layer is determined such as to match guided-waves in the synthetic data to guided-waves in the seismic data.

4. The method of claim 1 , further comprising:
producing the model used to generate the synthetic data using one or more initial maps of P-wave velocity, density, S-wave velocity and P-wave velocity to S-wave velocity ratio.

5. The method of claim 1 , further comprising:
editing the model of the underground formation to reduce changes in wave kinematics due to the pseudo-δ layer; and
performing an acoustic FWI using the edited model to obtain the model used for locating the sought-after natural resources.

6. The method of claim 1 , wherein the pseudo-δ layer has a negative value for δ and a null value for ϵ.

7. The method of claim 1 , wherein the FWI is an acoustic FWI.

8. The method of claim 1 , wherein the model includes one or more maps of P-wave velocity, S-wave velocity, anisotropy, and attenuation.

9. A seismic data processing apparatus comprising:
an interface configured to obtain seismic data acquired over an underground formation covered by a water layer; and
a processor configured
to perform a full-waveform inversion, FWI, of the seismic data using a model with a pseudo-δ layer located directly underneath the water layer to generate synthetic data, the FWI updating the model to minimize differences between the seismic data and the synthetic data, and
to locate sought-after natural resources in the underground formation using the model of the underground formation as updated by the FWI.

10. The seismic data processing apparatus of claim 9 , wherein the pseudo-δ layer is less than 100 m thick.

11. The seismic data processing apparatus of claim 9 , wherein the processor is configured to determine the pseudo-δ layer such as to match guided-waves in the synthetic data to guided-waves in the seismic data.

12. The seismic data processing apparatus of claim 9 , wherein the processor is further configured:
to produce the model used to generate the synthetic data using one or more initial maps of P-wave velocity, density, S-wave velocity and P-wave velocity to S-wave velocity ratio.

13. The seismic data processing apparatus of claim 9 , wherein the processor is further configured:
to edit the model of the underground formation to reduce changes in wave kinematics caused by the pseudo-δ layer; and
to perform an acoustic FWI using the edited model to obtain the model used for locating the sought-after natural resources.

14. The seismic data processing apparatus of claim 9 , wherein the pseudo-δ layer has a negative value for δ and a null value for E.

15. The seismic data processing apparatus of claim 9 , wherein the FWI is an acoustic FWI.

16. The seismic data processing apparatus of claim 9 , wherein the model includes one or more of P-wave velocity, S-wave velocity, anisotropy, and attenuation.

17. A computer readable recording medium storing executable codes that when executed by a computer make the computer perform a seismic exploration method, the method comprising:
obtaining seismic data acquired over an underground formation covered by a water layer;
performing a full-waveform inversion, FWI, of the seismic data using a model with a pseudo-δ layer located directly underneath the water layer to generate synthetic data, the FWI updating the model to minimize differences between the seismic data and the synthetic data; and
locating sought-after natural resources in the underground formation using the model of the underground formation updated by the FWI.

18. The computer readable recording medium of claim 17 , wherein the pseudo-δ layer is less than 100 m thick and/or is determined to match guided-waves in the synthetic data to guided-waves in the seismic data.

Assignees

• Cgg Services Sas

Inventors

• Ratcliffe Andrew
• Henstock Cris
• Gao Wenlei
• Masmoudi Nabil

Classifications

• G01V1/282 Primary

  Application of seismic models, synthetic seismograms · CPC title

• G01V2210/65

  Source localisation, e.g. faults, hypocenters or reservoirs · CPC title

• G01V2210/42

  Waveform, i.e. using raw or pre-filtered trace data · CPC title

• G01V2210/675

  Wave equation; Green's functions · CPC title

• G01V2210/673

  Finite-element; Finite-difference · CPC title