(19)
(11) EP 0 353 962 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
27.03.1991 Bulletin 1991/13

(43) Date of publication A2:
07.02.1990 Bulletin 1990/06

(21) Application number: 89307720.6

(22) Date of filing: 28.07.1989
(51) International Patent Classification (IPC)5: E21B 29/00
(84) Designated Contracting States:
DE FR GB

(30) Priority: 30.07.1988 GB 8818216
12.09.1988 GB 8821326

(71) Applicant: Tri-State Oil Tool (UK), a division of Baker Hughes Limited
Aberdeen AB2 OES (GB)

(72) Inventor:
  • Doig, Thomas
    Aberdeen (GB)

(74) Representative: Pacitti, Pierpaolo A.M.E. et al
Murgitroyd and Company 373 Scotland Street
Glasgow G5 8QA
Glasgow G5 8QA (GB)


(56) References cited: : 
   
       


    (54) Casing cutters


    (57) There is described a casing cutter of the type having a pivotable milling arm (10) which pivots outwards to trace a substantially conical path during rotation of the cutter. The milling arm is provided with an effective cutting edge (18, 20) which has an offset with respect to a notional axial reference line of the arm which passes through the pivot axis of the arm. The offset of each cutting edge is a distinct combination of circumferential offset and radial offset from the notional axial reference line so that a different effective cutting edge is presented to the casing to be cut when the cutter is used to cut a plurality of concentric casings of different diameters.







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