Surface wave tomography using sparse data acquisition

Patent metadata

Field	Value
Publication number	US-10338242-B2
Application number	US-201615157567-A
Country	US
Kind code	B2
Filing date	May 18, 2016
Priority date	May 20, 2015
Publication date	Jul 2, 2019
Grant date	Jul 2, 2019

Abstract

Method and system for ongoing monitoring for underground structure at or near a production wellpad is provided. The system includes a sparse acquisition grid and utilizes information obtained from Rayleigh waves to monitor subsurface structures.

First claim

The invention claimed is:

1. A method for monitoring a frozen subsurface structure to detect thawing-related problems, the method comprising:
obtaining seismic data;
estimating travel time or phase delay or both of Rayleigh waves in the seismic data at a central frequency;
performing tomography to the travel time or the phase delay estimated at the central frequency to obtain a slice of seismic velocity at the central frequency;
repeating the estimating of the travel time or phase delay or both and the performing of the tomography to the travel time or the phase delay for a range of central frequencies;
performing a dispersion inversion on slices of seismic velocity for the range of central frequencies to obtain a 3-D velocity cube in depth, the 3-D velocity cube in depth providing an indication of thawing of the frozen subsurface structure; and
monitoring the thawing of the frozen subsurface structure via repeating at least the obtaining of the seismic data every day, every few days, or bi-weekly to determine a progression of the thawing.

2. The method of claim 1 , wherein the subsurface structure includes a near surface layer over a hydrocarbon production reservoir.

3. The method of claim 1 , wherein the seismic data is obtained using a sparse acquisition grid that includes between about 1 to about 25 seismic sources.

4. The method of claim 1 , wherein the seismic data is obtained using a non-uniform grid of seismic sources.

5. The method of claim 1 , wherein the seismic data is obtained using a non-uniform grid of seismic receivers.

6. The method of claim 1 , wherein the range of central frequencies is between about 0.1 Hz or about 50 Hz.

7. The method of claim 1 , wherein the monitoring is continuous for at least about one month.

8. The method of claim 1 , wherein the monitoring is continuous for at least about a year.

9. The method of claim 1 , wherein the monitoring monitors production anomalies.

10. A method for monitoring a frozen subsurface structure to detect thawing-related problems, the method comprising:
obtaining seismic data using a sparse acquisition grid;
estimating travel time or phase delay or both of Rayleigh waves in the seismic data at a central frequency;
performing tomography to the travel time or the phase delay estimated at the central frequency to obtain a slice of seismic velocity at the central frequency;
repeating the estimating of the travel time or phase delay or both and the performing of the tomography to the travel time or the phase delay for a range of central frequencies;
performing a dispersion inversion on slices of seismic velocity for the range of central frequencies to obtain a 3-D velocity cube in depth, the 3-D velocity cube in depth providing an indication of thawing of the frozen subsurface structure; and
f) monitoring the thawing of the frozen subsurface structure via repeating at least the obtaining of the seismic data every day, every few days, or bi-weekly to determine a progression of the thawing.

11. The method of claim 10 , wherein the sparse acquisition grid includes less than about 25 seismic sources.

12. The method of claim 10 , wherein the sparse acquisition grid includes less than about 10 seismic sources.

13. The method of claim 10 , wherein the sparse acquisition grid includes 1 seismic source.

14. The method of claim 10 , wherein the subsurface structure includes a near surface layer over a hydrocarbon production reservoir.

15. The method of claim 10 , wherein the range of central frequencies is between about 0.1 Hz or about 50 Hz.

16. The method of claim 10 , wherein the monitoring is continuous for at least about one month.

17. The method of claim 10 , wherein the monitoring is continuous for at least about one year.

18. The method of claim 1 , wherein the thawing-related problems include deformation or compaction of the frozen subsurface structure.

19. The method of claim 1 , wherein the thawing is caused by steam-assisted production.

20. The method of claim 1 , wherein the seismic data is obtained via emitting a shot from at least one seismic source.

Assignees

• Conocophillips Co

Inventors

• Kazinnik Roman
• Davidson Michael
• Tura Ali
• Janssen Aaron L
• Mosher Charles C
• Darnell Ronnie B

Classifications

• G01V2210/169

  Sparse arrays · CPC title

• G01V2210/21

  Frequency-domain filtering, e.g. band pass · CPC title

• G01V1/305

  Travel times · CPC title

• G01V2210/6222

  Velocity; travel time · CPC title

• G01V1/282

  Application of seismic models, synthetic seismograms · CPC title