DETERMINING THE QUALITY OF A SEISMIC INVERSION

• US 20110051553A1
• Filed: 03/24/2010
• Published: 03/03/2011
• Est. Priority Date: 08/25/2009
• Status: Active Grant

• Current Assignee: WesternGeco LLC (Schlumberger NV)
• Original Assignee: WesternGeco LLC (Schlumberger NV)
• Inventors: Wheeler, Mark, Scott, Ian Richard
• Granted Patent: US 8,923,093 B2
• Time in Patent Office: Days
• US Class Current: 367/38
• CPC Class Codes: G01V 1/282 Application of seismic models, synthetic seismograms
• CPC Class Codes: G01V 2200/14 Quality control

Abstract

A method for evaluating a quality of a seismic inversion. The method includes performing a first match between seismic data and borehole seismic data at one or more borehole locations to generate an estimate of a wavelet in the seismic data. The method then performs a seismic inversion on the seismic data using the estimate of the wavelet to generate inverted seismic data. After performing the seismic inversion, the method converts the inverted seismic data into one or more reflectivity traces. The method then includes performing a second match between the one or more reflectivity traces and one or more traces in the seismic data and performing a third match between the one or more reflectivity traces and one or more traces in the borehole seismic data. After performing the second and third matches, the method determines the quality of the seismic inversion based on the first match, the second match, the third match or combinations thereof.

Claims

1. A method for evaluating a quality of a seismic inversion, comprising:

(a) performing a first match between seismic data and borehole seismic data at one or more borehole locations to generate an estimate of a wavelet in the seismic data;

(b) performing the seismic inversion on the seismic data using the estimate of the wavelet to generate inverted seismic data;

(c) converting the inverted seismic data into one or more reflectivity traces;

(d) performing a second match between the one or more reflectivity traces and one or more traces in the seismic data;

(e) performing a third match between the one or more reflectivity traces and one or more traces in the borehole seismic data; and

(f) determining the quality of the seismic inversion based on the first match, the second match, the third match or combinations thereof.

2. The method of claim 1, wherein the first match is performed using a borehole matching technique.

3. The method of claim 1, wherein the seismic data is processed in preparation for the seismic inversion.

4. The method of claim 3, further comprising optimizing the seismic inversion based on the quality of the seismic inversion by:

modifying one or more processing parameters used when the seismic data is processed;

modifying one or more inversion parameters in an inversion algorithm used in the seismic inversion;

or

combinations thereof.

5. The method of claim 4, wherein optimizing the seismic inversion further comprises repeating steps (a)-(f) until the quality of the seismic inversion is above a predetermined value.

6. The method of claim 3, wherein the processed seismic data is a migrated dataset of seismic data in the time domain or in the depth domain.

7. The method of claim 3, wherein the processed seismic data is pre-stack seismic data or post-stack seismic data.

8. The method of claim 1, wherein the borehole seismic data is acquired from one or more well logging devices or obtained from one or more vertical seismic profiles.

9. The method of claim 1, wherein the seismic inversion removes one or more effects of the estimate of the wavelet from the seismic data to create a model of one or more rock properties of the earth.

10. The method of claim 1, wherein the one or more reflectivity traces are impedance traces, density traces, velocity traces, or combinations thereof.

11. The method of claim 1, wherein performing the seismic inversion comprises adding a low frequency model for one or more properties of the earth derived from the seismic inversion.

12. The method of claim 1, wherein the second match determines how well the estimate of the wavelet was removed from the one or more reflectivity traces on a trace by trace basis.

13. The method of claim 1, wherein the third match determines how well the one or more reflectivity traces modeled the one or more reflectivity traces of the borehole seismic data.

14. The method of claim 1, wherein the quality of the seismic inversion is determined by comparing the first match, second match and third match using plots, quantification algorithms or combinations thereof.

15. The method of claim 1, further comprising optimizing the seismic inversion based on the quality of the seismic inversion, wherein optimizing the seismic inversion comprises modifying one or more inversion parameters in an inversion algorithm used in the seismic inversion.

16. The method of claim 1, further comprising:

optimizing the seismic inversion to generate optimized inverted seismic data based on a comparison between the quality of the seismic inversion and a quality of a previously performed seismic inversion, wherein the previously performed seismic inversion was performed on the seismic data using one or more different parameters than what were used for the seismic inversion; and

estimating hydrocarbon reserves based on the optimized inverted seismic data.

17. A method for evaluating a quality of a seismic inversion, comprising:

processing seismic data in preparation for the seismic inversion

performing a first match between the processed seismic data and borehole seismic data at one or more borehole locations to estimate one or more wavelets that are embedded in the processed seismic data;

performing the seismic inversion on the seismic data using the wavelets to generate inverted seismic data;

converting the inverted seismic data into one or more reflectivity traces;

performing a second match between the one or more reflectivity traces and one or more traces in the seismic data;

performing a third match between the one or more reflectivity traces and one or more traces in the borehole seismic data; and

determining the quality of the seismic inversion based on the first match, the second match, the third match or combinations thereof.

18. The method of claim 17, wherein performing the seismic inversion comprises determining a single wavelet from the wavelets.

19. The method of claim 17, wherein performing the seismic inversion comprises removing a varying phase in the wavelets such that the wavelets are the same zero phase wavelet.

20. The method of claim 19, wherein the varying phase is removed using a space-adaptive wavelet equalization analysis.