(19)
(11) EP 0 352 979 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
05.02.1992 Bulletin 1992/06

(43) Date of publication A2:
31.01.1990 Bulletin 1990/05

(21) Application number: 89307415.3

(22) Date of filing: 20.07.1989
(51) International Patent Classification (IPC)5: E21B 7/24, E21B 25/00, B06B 1/16
(84) Designated Contracting States:
BE DE ES FR GB IT NL SE

(30) Priority: 28.07.1988 GB 8818024

(71) Applicant: The British Petroleum Company p.l.c.
London EC2Y 9BU (GB)

(72) Inventors:
  • Bollands, Martin Arthur
    Weybridge Surrey KT13 0VJ (GB)
  • Chinery, David
    Sunbury-on-Thames Middlesex, TW16 7LN (GB)
  • Woolmington, Thimothy Ray
    Sunbury-on-Thames Middlesex, TW16 7LN (GB)

(74) Representative: MacLeod, Malcolm et al
BP INTERNATIONAL LIMITED Patents Division Chertsey Road
Sunbury-on-Thames Middlesex TW16 7LN
Sunbury-on-Thames Middlesex TW16 7LN (GB)


(56) References cited: : 
   
       


    (54) Variable amplitude drill


    (57) A vibratory core drill comprises a housing (11) adapted for connection to a drill string and a variable amplitude rotor (10) rotably mounted in the housing (11), the variable amplitude rotor (10) comprising a central shaft (1), an inner shell (2), the inner and outer shells (2) and (3) being capable of rotation relative to one another and capable of being locked in any desired relationship and released.
    The variable amplitude rotor enables the amplitude of oscillation to be varied to cope with formations of different characteristics, eg, sand and clay.
    The drill is suitable for use in drilling core samples for evaluating the mineral potential of deposits and for environmental monitoring to detect possible contamination.







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