(19)
(11) EP 0 636 763 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
09.08.1995 Bulletin 1995/32

(43) Date of publication A2:
01.02.1995 Bulletin 1995/05

(21) Application number: 94305423.9

(22) Date of filing: 22.07.1994
(51) International Patent Classification (IPC)6: E21B 47/12
(84) Designated Contracting States:
FR GB NL

(30) Priority: 26.07.1993 US 97570

(71) Applicant: BAKER-HUGHES INCORPORATED
Houston Texas 77027-5115 (US)

(72) Inventors:
  • Meyer, Wallace
    Spring, Texas 77379 (US)
  • Wisler, Macmillan
    Kingwood, Texas 77339 (US)
  • Hay, Arthur
    Spring, Texas 77379 (US)

(74) Representative: Davies, Christopher Robert 
Frank B. Dehn & Co. Imperial House 15-19 Kingsway
London WC2B 6UZ
London WC2B 6UZ (GB)


(56) References cited: : 
   
       


    (54) Method and apparatus for electric/acoustic telemetry in a well


    (57) A drill collar section (22) of a drill string (16) (i.e. at the downhole end of the drill string) includes an electric transmitter/receiver assembly (26) which communicates with an electric/acoustic repeater assembly (28) which communicates with an acoustic transmitter/ receiver assembly (29) uphole of the drill string by the transmission and receipt of electric and acoustic signals through the drill string. With drill strings that include downhole motors (30) the electric transmitter/receiver assembly may be positioned above or below the motor. Uphole telemetry comprises an electric current induced in the drill string by the downhole electric transmitter (26). The electric current contains encoded information of downhole conditions and travels up the drill string where it is detected at the electric receiver of the electric/acoustic repeater (28). The received signal is processed to drive the acoustic transmitter of the electric/acoustic repeater. An acoustic signal containing the encoded information is induced into the drill string by this acoustic transmitter and permeates up the drill string to the uphole acoustic receiver (29). This received signal is processed and utilized to evaluate and/or optimize the drilling process or to evaluate the earth formations being drilled. Downhole telemetry comprises an acoustic signal induced in drill string (16) by the uphole acoustic transmitter (29). The acoustic signal contains encoded information of uphole commands and travels down the drill string where it is detected at the acoustic receiver of the electric/acoustic repeater (28). The received signal is processed to drive the electric transmitter of the electric/acoustic repeater. An electric signal containing the encoded information is induced in the drill string by this electric transmitter and travels down the drill string to the downhole electric receiver (26). This received signal is processed and utilized to command a downhole processor (i.e., computer).






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