Communications – electrical: acoustic wave systems and devices – Wellbore telemetering – Through drill string or casing
Patent
1983-10-17
1985-12-31
Tarcza, Thomas H.
Communications, electrical: acoustic wave systems and devices
Wellbore telemetering
Through drill string or casing
175 40, G01V 140
Patent
active
045625590
ABSTRACT:
In a borehole telemetry system for acoustically transmitting data over a pipe suspended in a borehole, the level of noise in the data stream is inherently high due to the environment existing in a drilling operation and to the physical characteristics of a drill string. It has been discovered that certain discrete frequency passbands exist in a drill string which permit transmission of an acoustic signal with a minimum level of attenuation. In addition, it is now known that a fine structure exists within these frequency passbands which presents gaps or voids that attenuate the signal at a much higher rate. These gaps are on the order of 20 Hz.
By generating an acoustic signal at a precise frequency spectrum within these passbands and then phase shifting the signal before its transmission, the energy spectrum of the transmitted signal is spread out over a sufficient frequency range to bridge these gaps.
REFERENCES:
patent: 3889228 (1975-06-01), Shawhan
patent: 4215427 (1980-07-01), Waggener et al.
Barnes and Kirkwood, "Passbands for Acoustic Transmission in an Idealized Drill String", Journal of the Acoustical Society of America, vol. 51, No. 5, (Part 2), (1972), pp. 1606-1608.
Sharp H. Eugene
Smither Miles A.
Johnson, Jr. William E.
Kaiser K. R.
McClenny Carl O.
NL Sperry Sun, Inc.
Tarcza Thomas H.
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