METHOD FOR SEPARATING INDEPENDENT SIMULTANEOUS SOURCES

• US 20100299070A1
• Filed: 08/06/2010
• Published: 11/25/2010
• Est. Priority Date: 08/15/2008
• Status: Active Grant

• Current Assignee: BP Corporation North America Incorporated (BP PLC)
• Original Assignee: BP Corporation North America Incorporated (BP PLC)
• Inventors: Abma, Raymond L.
• Granted Patent: US 8,559,270 B2
• Time in Patent Office: Days
• US Class Current: 702/14
• CPC Class Codes: G01V 1/00 Seismology; Seismic or acoustic prospecting or detecting
• CPC Class Codes: G01V 1/005 with exploration systems emitting special signals, e.g. frequency swept signals, pulse sequences or slip sweep arrangements
• CPC Class Codes: G01V 1/368 Inverse filtering
• CPC Class Codes: G01V 1/37 specially adapted for seismic systems using continuous agitation of the ground , e.g. using pulse compression of frequency swept signals for enhancement of received signals
• CPC Class Codes: G01V 2210/24 Multi-trace filtering

Abstract

This is a method of separating simultaneous sources that uses an inversion-type approach. Each source will preferably activated at a random time with respect to the others. These random delays tend to make the interference between sources incoherent while the reflections create coherent events within a series of shots. The shot separation is performed via a numerical inversion process that utilizes the sweeps for each shot, the start times of each shot, and the coherence of reflection events between nearby shots. Implementation of this method will allow seismic surveys to be acquired faster and cheaper.

Claims

1. A method of seismic exploration above a region of the subsurface containing structural or stratigraphic features conducive to the presence, migration, or accumulation of hydrocarbons, wherein is provided a blended source seismic survey containing at least two interfering seismic source excitations therein, comprising the steps of:

(a) within a computer, accessing at least a portion of said blended source seismic survey;

(b) selecting one of said at least two interfering seismic source excitations;

(c) obtaining at least a time of activation and location coordinates for said selected one of said at least two interfering seismic source excitations;

(d) using at least said time of activation and said location coordinates for said selected one of said at least two interfering seismic source excitations, separating said selected source excitation from said at least two interfering seismic source excitations using sparse inversion, thereby producing at least one single source gather; and

(e) using said at least one single source gather to explore for hydrocarbons within said region of the subsurface.

2. The method of seismic exploration according to claim 1, wherein said at least two interfering seismic source excitations are created by a same seismic source.

3. The method of seismic exploration according to claim 1, wherein there is a time interval between each of said at least two interfering seismic source excitations and wherein said time interval is a random time interval.

4. The method of claim 1, wherein step (d) comprises the step of:

(d1) performing at least steps (b), (c), and (d) a plurality of times for a plurality of different source excitations, thereby producing a plurality of single source gathers, and,

and wherein step (e) comprises the step of;

(e1) using said plurality of single source gathers to explore for hydrocarbons within said region of the subsurface.

5. The method of claim 1, wherein step (d) comprises the steps of:

(d1) using at least said time of activation and said location coordinates for said selected one of said at least two interfering seismic source excitations to separate said selected source excitation from said at least two interfering seismic source excitations using sparse inversion by solving the equation;

d=Γ

Sm,

for the matrix m thereby producing a single source gather, where m is said single source gather,

d is a matrix representation of the recorded seismic data,

S is a matrix or operator that describes the similarity between nearby shots, and

Γ

is a matrix that defines the blending or mixing of the individual sources.

6. The method of claim 1, wherein step (d) comprises the steps of:

(d1) using at least said time of activation and said location coordinates for said selected one of said at least two interfering seismic source excitations to separate said selected source excitation from said at least two interfering seismic source excitations using sparse inversion by solving the equation;

Wd=WΓ

Sm,

for the matrix m thereby producing a single source gather, where

m is said single source gather,

d is a matrix representation of the recorded seismic data,

S is a matrix or operator that describes the similarity between nearby shots,

Γ

is a matrix that defines the blending or mixing of the individual sources, and,

W is a known matrix of weights.

7. A method of collecting marine seismic data seismic above a region of the subsurface containing structural or stratigraphic features conducive to the presence, migration, or accumulation of hydrocarbons, comprising the steps of:

(a) selecting a plurality of shot locations;

(b) activating a first source proximate to a first one of said plurality of shot locations;

(c) activating a second source proximate to a second one of said plurality of shot locations at an interval of time after said first source activation, said interval of time being at least approximately a random interval of time and said interval of time being short enough that said first source activation and said second source activation interfere;

(d) recording said first source activation and said second source activation through at least one seismic receiver;

(e) performing steps (b) and (c) a plurality of times, thereby acquiring a blended source seismic survey, said blended source seismic survey containing at least two interfering seismic source excitations therein;

(f) within a computer, accessing at least a portion of said blended source seismic survey;

(g) selecting one of said at least two interfering seismic source excitations;

(h) separating said selected source excitation from said at least two interfering seismic source excitations using sparse inversion, thereby producing a single source gather; and

(i) using said single source gather to explore for hydrocarbons within said region of the subsurface.

8. The method of seismic exploration according to claim 7, wherein said first source and said second source are a same seismic source.

9. The method of seismic exploration according to claim 7, wherein said first one of said plurality of shot locations and said second one of said plurality of shot locations are a same shot location.

10. The method of claim 7, wherein step (h) comprises the steps of:

(h) separating said selected source excitation from said at least two interfering seismic source excitations by solving the equation;

d=Γ

Sm,

for the matrix m thereby producing a single source gather, where

m is said single source gather,

d is a matrix representation of the recorded seismic data,

S is a matrix or operator that describes the similarity between nearby shots, and

Γ

is a matrix that defines the blending or mixing of the individual sources,

11. The method of claim 7, wherein step (h) comprises the steps of:

(h1) using at least said time of activation and said location coordinates for said selected one of said at least two interfering seismic source excitations to separate said selected source excitation from said at least two interfering seismic source excitations using sparse inversion by solving the equation;

Wd=WΓ

Sm,

for the matrix m thereby producing a single source gather, where

m is said single source gather,

d is a matrix representation of the recorded seismic data,

S is a matrix or operator that describes the similarity between nearby shots,

Γ

is a matrix that defines the blending or mixing of the individual sources, and,

W is a known matrix of weights.