(19)
(11) EP 1 143 105 A8

(12) CORRECTED EUROPEAN PATENT APPLICATION

(48) Corrigendum issued on:
24.04.2002 Bulletin 2002/17

(43) Date of publication:
10.10.2001 Bulletin 2001/41

(21) Application number: 01201151.6

(22) Date of filing: 28.03.2001
(51) International Patent Classification (IPC)7: E21B 47/12, E21B 7/06, E21B 4/02, E21B 17/10
(84) Designated Contracting States:
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR
Designated Extension States:
AL LT LV MK RO SI

(30) Priority: 04.04.2000 US 542607
01.05.2000 US 200941 P
02.05.2000 US 563801

(71) Applicants:
  • SCHLUMBERGER HOLDINGS LIMITED
    Road Town, Tortola (VG)

    GB NL 
  • SCHLUMBERGER TECHNOLOGY B.V.
    2514 JG The Hague (NL)

    DK ES IT 

(72) Inventors:
  • Askew, Warren
    Houston, Texas 77096 (US)
  • Dorel, Alain P.
    Houston, Texas 77082 (US)

(74) Representative: Macquet, Christophe 
Schlumberger Cambridge Research Ltd, High Cross, Madingley Road
Cambridge CB3 0EL
Cambridge CB3 0EL (GB)

   


(54) Directional drilling system


(57) A system is provided for directionally drilling a wellbore using a drill string having a mud motor, a drill bit, and a drive shaft for transmitting torque from the mud motor to the drill bit. The system includes a variable gauge stabilizer that is adjustable between retracted and deployed positions for influencing the drop or build angle of the drill bit. An instrument is carried within the drill string adjacent the drill bit for measuring data while drilling, and a telemetry system transmits the measured data to a driller at the surface. The telemetry system includes a transmitter disposed in the drill string beneath the mud motor for inducing a signal corresponding to the measured data into the subsurface formation surrounding the wellbore, and a receiver disposed in the drill string above the mud motor for detecting and recovering the measured data from the induced signal.