1 / 61

Hydro-frac Source Estimation by Time Reversal Mirrors

Hydro-frac Source Estimation by Time Reversal Mirrors. Weiping Cao and C. Boonyasiriwat. UTAM, The University of Utah. Outline. Motivation. Methodology. Numerical Examples. Conclusions. Outline. Motivation. Methodology. Numerical Examples. Conclusions. Motivation.

lacota-bailey
Download Presentation

Hydro-frac Source Estimation by Time Reversal Mirrors

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Hydro-frac Source Estimation by Time Reversal Mirrors Weiping Cao and C. Boonyasiriwat UTAM, The University of Utah

  2. Outline • Motivation • Methodology • Numerical Examples • Conclusions

  3. Outline • Motivation • Methodology • Numerical Examples • Conclusions

  4. Motivation • Hydro-frac is important for oil recovery operations; • Using time reversal mirror (TRM) method, only a local velocity model near the well needed; • Potential for super-resolution and super-stacking properties from TRM.

  5. Outline • Motivations • Methodology • Numerical Examples • Conclusions

  6. Methodology • TRM imaging; • Apply TRM imaging to locating hydro-fracs by wavefield extrapolation; • Detailed implementation.

  7. Multiples Primary TRM Imaging Time Reversal Mirror Time Image source location with natural Green’s functions No velocity model needed

  8. TRM imaging g : passive data generated by hydro-fracs Problem: finding Apply TRM to Locating Hydro-fracs s Solution: extrapolate VSP or seismic while drilling (SWD) data.

  9. Forward extrapolation: Backward extrapolation: : convolution g x : crosscorrelation go Extrapolate VSP or SWD Data to obtain g go x Only a local vel. model needed

  10. Methodology Summary for the implementation: Record VSP or SWD data as natural GF; Extrapolate VSP or SWD data to obtain semi-natural GFs between surface and image points using the local velocity model near the well; Cross-correlate these semi-natural GFs to the passive seismic data generated by hydro-fracs.

  11. Outline • Motivation • Methodology Numerical Examples • Conclusions

  12. Numerical Examples Synthetic Tests with SEG/EAGE Salt Model: Hydro-frac imaging with correct source excitation times; Hydro-frac imaging with strong background noise; Hydro-frac imaging with incorrect source excitation times;

  13. SEG/EAGE Salt Model 0 4 (km/s) Z (km) 2 (km/s) 3.5 0 16 X (km) Synthetic Data Generation Synthetic data: RVSP or SWD data, Passive seismic gathers

  14. Image with Correct Source Excitation Times TRM imaging with forward extrapolation Actual hydro-frac location: (10 km, 3.4 km) 3.2 3.5 km/s Z (km) 3.7 2.5 8 12 X (km)

  15. Image with Correct Source Excitation Times TRM imaging with backward extrapolation Actual hydro-frac location: (10 km, 3.01 km) 2.7 3.1 km/s Z (km) 3.2 2.3 8 12 X (km)

  16. Image with Strong Background Noise Synthetic Passive Gather Noisy Gather: S/N =10,495 0 0 Time (s) Time (s) 6 6 0 Receiver X (km) 15 0 Receiver X (km) 15 Actual hydro-frac source location: (10 km, 3.01 km)

  17. Image with Strong Background Noise TRM Image from the Noisy Gather 2.7 1 Z (km) -0.5 3.2 8 12 X (km)

  18. Image with Strong Background Noise TRM Image from the Noisy Gather: S / N =1 / 10496 2.7 1 Z (km) -0.5 3.2 8 12 X (km)

  19. 3.2 20 ms advance Z (km) 3.7 12 8 X (km) 3.2 Exact source excitation time Z (km) 3.7 12 8 X (km) 3.2 20 ms delay Z (km) 3.7 12 8 X (km) Image with Incorrect Source Excitation Times

  20. Outline • Motivation • Methodology • Numerical Examples Conclusions

  21. Conclusions TRM is applied to locate hydro-fracs with VSP or SWD data, and provide accurate images when we use exact source excitation times. TRM images show strong resilience to white noise. TRM images are sensitive to source excitation times. 2-D median assumption.

  22. Acknowledgments We thank the 2007 UTAM sponsors for the support.

  23. Image with Strong Background Noise 1 2.7 Z (km) -0.5 3.2 8 12 X (km)

  24. Image with Strong Background Noise 1 2.7 Z (km) -0.5 3.2 8 12 X (km)

  25. Image with Correct Source Excitation Times 3.2 3.5 km/s Z (km) 3.7 2.5 8 12 X (km)

  26. Interferometric Imaging Implementation Step 1: Extrapolate of VSP data Step2: Image hydro-fracture sources

  27. Outline • Motivations • Methodology • Numerical Examples • Conclusions

  28. Methodology

  29. Numerical Examples

  30. Numerical Examples SEG/EAGE Salt Model 0 Z (km) 3.5 0 16 X (km)

  31. Synthetic Seismic Data

  32. original

  33. Subtract 20 for frac(advance)

  34. Plus 20 for frac (delay)

  35. Multiples Primary TRM Imaging Time Reversal Mirror Time Image source location with natural Green’s functions No velocity model needed

  36. Multiples Primary TRM Imaging Time Reversal Mirror Time Image source location with natural Green’s functions No velocity model needed

  37. : passive data generated by hydro-fracs Apply TRM to Locating Hydro-fracs Hydro-frac Location Problem: finding Solution: extrapolate VSP or seismic while drilling (SWD) data.

More Related