Claims
- 1. A frequency domain semblances method comprising:
(a) transforming data from a first acoustic signal into the frequency domain; (b) calculating a frequency semblance value from said data, said frequency semblance value corresponding to a first frequency and a first slowness for said data.
- 2. The frequency domain method of claim 1, wherein said transforming step further includes transforming second data from a second acoustic signal into the frequency domain, and wherein said frequency semblance value is additionally calculated from said second data.
- 3. The method of claim 1, further comprising:
(c) graphically displaying a set of said frequency semblance values.
- 4. The method of claim 1, further comprising:
(d) generating a set of said frequency semblance values.
- 5. The method of claim 4, further comprising:
(e) applying a frequency filter to said data, said frequency filter corresponding to one or more ranges of frequencies, and wherein said frequency filter eliminates portions of said data that correspond to said ranges of frequencies.
- 6. The method of claim 5, wherein said one or more ranges of frequencies are selected based upon predetermined patterns in said set of frequency semblance values.
- 7. The method of claim 1, wherein a set of frequency semblance values are calculated, said set of frequency semblance values including at least one maximum semblance value, said maximum semblance value corresponding to a first peak frequency, a first peak slowness, and an energy value.
- 8. The method of claim 7, wherein said at least one maximum semblance value corresponds to a set of high frequency semblance values, said set of high frequency semblance values corresponding to a characteristic of said first acoustic signal.
- 9. The frequency domain method of claim 1, wherein said first acoustic signal is received at a plurality of depths in a borehole, said transforming step further including the transformation of data from each of said plurality of depths in said borehole for calculation of said semblance value.
- 10. The frequency domain method of claim 9, wherein said set of frequency semblance values are calculated downhole in a borehole.
- 11. The frequency domain method of claim 9, wherein said set of frequency semblance values are calculated at an above surface location.
- 12. The frequency domain method of claim 9, wherein a set of frequency semblance values are calculated and said set of frequency semblance values correspond to a first peak frequency, a first peak slowness, a peak energy value, and a peak shape.
- 13. The frequency domain method of claim 12, wherein said first peak frequency, said first peak slowness, and said peak energy value are calculated by a downhole processor in a wellbore.
- 14. The frequency domain method of claim 13, wherein at least one of said first peak frequency, first peak slowness, peak energy value, and peak shape are calculated at a sub-surface location to yield a calculated value, said at least one calculated value being stored downhole, said method further comprising calculating at least a second calculated value at an above ground location.
- 15. A method for data compression, comprising:
(a) recording a first waveform at a plurality of data points; (b) compressing said data points by a first protocol to derive a first compressed data; (c) compressing said data points by a second protocol to derive second compressed data; (d) comparing said first compressed data to said second compressed data to determine which would require less memory for storage.
- 16. The method of claim 15, where said first protocol measures the difference between data points.
- 17. The method of claim 15, wherein said first protocol measures the difference between measured differences.
- 18. The method of claim 17, wherein said steps of compressing include compressing said data points by a third protocol to derive third compressed data, said first protocol being a bit encoding protocol, said second protocol being a difference encoding protocol, and said third protocol being a difference of the differences protocol.
- 19. A frequency domain semblances method comprising:
(a) generating a first acoustic signal at a first depth in a borehole; (b) receiving said first acoustic signal at a first set of acoustic receivers proximate said first depth to generate a first series of received acoustic waveforms; (c) transforming said first series of received acoustic waveforms into the frequency domain; (d) calculating a first frequency semblance value from said data, said frequency semblance value corresponding to a first frequency and a first slowness for said data; (e) generating a second acoustic signal at a second depth in said borehole; (f) receiving said second acoustic signal at a second set of acoustic receivers proximate said second depth to generate a second series of received acoustic waveforms; (g) transforming said second series of received acoustic waveforms into the frequency domain; (h) calculating a second frequency semblance value from said data, said second frequency semblance value corresponding to a second frequency and a second slowness for said data; (i) correlating said first slowness and said second slowness with said first depth and said second depth.
- 20. The method of claim 19, wherein said correlating step yields a slowness-depth log of said borehole.
- 21. A method to combine time domain semblances, comprising:
(a) calculating from a first plurality of waveforms a first set of time domain semblance values corresponding to a first depth in a borehole, each of said time domain semblance values in said first set corresponding to a time and a slowness; (b) calculating from a second plurality of waveforms a second set of time domain semblance values corresponding to said first depth in a borehole, each of said time domain semblance values in said second set corresponding to a time and a slowness; (c) combining a first time domain semblance value from said first set and a second time domain semblance value from said second set, said first time domain semblance value and said second time domain semblance value corresponding to the same time and slowness.
- 22. The method of claim 21, wherein said combining step is multiplication.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application relates to provisional application serial No. 60/128,912 filed Apr. 12, 1999.
Continuations (1)
|
Number |
Date |
Country |
Parent |
09547304 |
Apr 2000 |
US |
Child |
10243471 |
Sep 2002 |
US |