Method and apparatus for deghosting seismic data

Patent metadata

Field	Value
Publication number	US-9784868-B2
Application number	US-201414295663-A
Country	US
Kind code	B2
Filing date	Jun 4, 2014
Priority date	Jun 10, 2010
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

Apparatus, computer instructions and method for deghosting seismic data related to a subsurface of a body of water. The method includes inputting data recorded by detectors that are towed by a vessel, the data being associated with waves travelling from the subsurface to the detectors; applying a migration procedure to the data to determine a first image of the subsurface; applying a mirror migration procedure to the data to determine a second image of the subsurface; joint deconvoluting the first image and the second image for deghosting a reflectivity of the subsurface; and generating a final image of the subsurface based on the deghosted reflectivity of the joint deconvoluting step.

First claim

What is claimed is:

1. A method for deghosting seismic data related to a subsurface of a body of water, the method comprising:
receiving data recorded with seismic detectors distributed along a streamer, the data being associated with waves travelling from the subsurface to the seismic detectors;
applying with a processing apparatus a migration procedure to the data to determine a first dataset indicative of the subsurface;
applying with the processing apparatus a mirror migration procedure to the data to determine a second dataset indicative of the subsurface;
joint deconvoluting with the processing apparatus the first dataset and the second dataset for deghosting a reflectivity of the subsurface; and
generating with the processing apparatus an image of the subsurface based on the deghosted reflectivity of the joint deconvoluting step.

2. The method of claim 1 , wherein the deghosting is performed during an imaging phase and not in a preprocessing phase with a processing apparatus.

3. The method of claim 1 , wherein no datuming step is performed on the data.

4. The method of claim 1 , wherein a travelling angle of the waves propagating from the subsurface to the detectors or from a surface of the water to the detectors is not restricted.

5. The method of claim 1 , wherein the data is three dimensional data and the migration, the mirror migration and the joint deconvolution are three dimensional procedures.

6. The method of claim 1 , wherein the data are collected from streamers having birds that are controlled to achieve a curved profile.

7. The method of claim 1 , wherein the migration procedure comprises:
recursively synthesizing an incident wave D(x, y, z+Δz, t) at a depth z+Δz from a previous incident wave D(x, y, z, t) at depth z.

8. The method of claim 1 , wherein the mirror migration procedure comprises:
recursively synthesizing an up-travelling wave U(x, y, z+Δz, t) at a depth z+Δz from a previous up-travelling wave U(x, y, z, t) at a depth z.

9. The method of claim 1 , wherein the joint deconvoluting comprises:
determining the reflectivity r(x, y, z), a minimum phase transfer function g min (z), and a maximum phase transfer function g max (z) based on equations:
d 1 ( x,y,z )= g min ( z )* r ( x,y,z ), and
d 2 ( x,y,z )= g max ( z )* r ( x,y,z ),

wherein z is a depth of a point relative to the surface of the water, and x and y are coordinates of the point in a plane substantially parallel with the surface of the water.

10. The method of claim 9 , wherein the g min (z) and g max (z) are three dimensional functions.

11. The method of claim 1 , wherein the migration is a depth migration.

12. The method of claim 1 , wherein the migration is a time migration.

13. The method of claim 1 , wherein the joint deconvolution comprises:
calculating a cost function C for determining the reflectivity, wherein the cost function C is given by:
C=Σ (x,y,z)εV {[ d 1 ( x,y,z )− g min ( z )* r ( x,y,z )] 2 +[ d 2 ( x,y,z )− g max ( z )* r ( x,y,z )] 2 },

where d 1 (x, y, z) is the first dataset, d 2 (x, y, z) is the second dataset, g min (z) is a minimum phase transfer function, g max (z) is a maximum phase transfer function, z is a depth of a point relative to the surface of the water, x and y are coordinates of the point in a plane substantially parallel with the surface of the water, and V is a predetermined volume.

14. The method of claim 1 , further comprising:
applying a (τ, p x , p y ) transform to the first dataset d 1 (x, y, z) and the second dataset d 2 (x, y, z), to transform the first dataset d 1 (x, y, z) into D 1 (p x , p y , τ) and the second dataset d 2 (x, y, z) into D 1 (p x , p y , τ).

15. The method of claim 1 , wherein the data includes recordings from hydrophones and geophones.

16. The method of claim 15 , wherein a result of the migration procedure is d 1 (x, y, z) and a result of the mirror migration procedure is d 2 (x, y, z) for hydrophone type receivers and a result of the migration procedure is d 3 (x, y, z) and a result of the mirror migration procedure is d 4 (x, y, z) for geophones.

17. The method of claim 16 , further comprising:
generating the image using a joint deconvolution of d 1 (x, y, z), d 2 (x, y, z), d 3 (x, y, z), and d 4 (x, y, z) and based on the following equations:
d 1 ( x,y,z )= g h min ( z )* r ( x,y,z );
d 2 ( x,y,z )= g h max ( z )* r ( x,y,z );
d 3 ( x,y,z )= g g min ( z )* c ( z )* r ( x,y,z ); and
d 4 ( x,y,z )= g g max ( z )* c ( z )* r ( x,y,z ),

where g h min and g g min are minimum phase transfer functions, g h max (z) and g g max (z) are maximum phase transfer functions, z is a depth of a point relative to the surface of the water, x and y are coordinates of the point in a plane substantially parallel with the surface of the water, and c(z) is a calibration operator.

18. A processing device for deghosting seismic data related to a subsurface of a body of water, the processing device comprising:
an interface configured to receive data recorded by detectors that are distributed along a streamer, the data being associated with waves travelling from the subsurface to the detectors; and
a processor connected to the interface and configured to,
apply a migration procedure to the data to determine a first dataset representative of the subsurface,
apply a mirror migration procedure to the data to determine a second dataset representative of the subsurface,
joint deconvolute the first dataset and the second dataset for deghosting a reflectivity of the subsurface, and
generate an image of the subsurface based on the deghosted reflectivity of the joint deconvoluting step.

19. The processing device of claim 18 , wherein the processor is configured to deghost the image during an imaging phase and not in a preprocessing phase.

20. A non-transitory computer readable medium including computer executable instructions, wherein the instructions, when executed, implement a method for deghosting seismic data related to a subsurface of a body of water, the method comprising:
inputting data recorded by detectors that are distributed along a streamer, the data being associated with waves travelling from the subsurface to the detectors;
applying a migration procedure to the data to determine a first dataset representative of the subsurface;
applying a mirror migration procedure to the data to determine a second dataset representative of the subsurface;
joint deconvoluting the first dataset and the second dataset for deghosting a reflectivity of the subsurface; and
generating an image of the subsurface based on the deghosted reflectivity of the joint deconvoluting step.

Assignees

• Cggveritas Services Sa
• Cgg Services Sas

Inventors

• Soubaras Robert

Classifications

• G01V1/362 Primary

  Effecting static or dynamic corrections; Stacking · CPC title

• G01V1/28 Primary

  Processing seismic data, e.g. for interpretation or for event detection (G01V1/48 takes precedence) · CPC title

• G01V1/282

  Application of seismic models, synthetic seismograms · CPC title

• G01V2210/56

  De-ghosting; Reverberation compensation · CPC title

• G01V1/3808

  Seismic data acquisition, e.g. survey design · CPC title