Communications – electrical: acoustic wave systems and devices – Seismic prospecting – Well logging
Patent
1981-10-09
1985-12-31
Cangialosi, Salvatore
Communications, electrical: acoustic wave systems and devices
Seismic prospecting
Well logging
367 25, 367 31, 367 27, 364422, 181102, G01V 140
Patent
active
045625565
ABSTRACT:
Shear and compressional velocities of acoustic waveforms in the earth formations surrounding a well bore are measured by analyzing the waveforms propagated through different lengths of substantially the same formation intervals. Phase analysis techniques applied to waveforms windowed for compressional waves are used to determine the propagation velocity of the compressional waves through the differential path lengths. The waveforms are then windowed for shear waves, the discrete fourier transforms of the windowed waveforms are taken, and the cross-spectral magnitude and phase for each frequency is computed as the product of the discrete fourier transform sample of one with the conjugate of the other. Several different moveouts are calculated, the resultant phases from each analyzed, and a band specified where the zero phase moveouts are roughly consistent. This ultimately specifies a final, accurate shear window moveout for determining, using phase analysis techniques, the shear propagation velocity characteristics of the respective earth formation intervals.
REFERENCES:
patent: 4210965 (1980-07-01), Ingram
patent: 4210966 (1980-07-01), Ingram
Aron et al., "Formation Compressional and Shear Interval Transit Time Logging by Means of Long Spacing & Digital Techniques", 10/78, pp. 1-11, SPE.
Piersol, "Time Delay Estimation Using Phase Data", 6/81, IEEE Transactions on Acoustics . . . , pp. 471-477.
Clay et al., "Use of a Two Dimensional Array to Receive an Unknown Signal . . . ", 2/69, Journal of the Acoust . . . , pp. 435-440.
Cheng et al., "Velocity and Attenuation from Full Waveform Acoustic Logs," 6/81, SPWLA 22nd Annual Logging Symposium, pp. 1-19.
Koerperich, "Shear Wave Velocities Determined from Long and Short Spaced Borehole Acoustic Devices, " 9/79, SPE, pp. 1-12.
Plona, "Observation of a Second Bulk Compressional Wave . . . Ultrasonic Frequencies, " 2/15/80. pp. 259-261, Appl. Phys. Lett.
Ingram John D.
Macknight Eileen E.
Cangialosi Salvatore
Lobo Ian J.
Schlumberger Technology Corporation
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