(19)
(11) EP 0 295 045 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
25.10.1989 Bulletin 1989/43

(43) Date of publication A2:
14.12.1988 Bulletin 1988/50

(21) Application number: 88305172.4

(22) Date of filing: 07.06.1988
(51) International Patent Classification (IPC)4: E21B 10/60, E21B 10/56
(84) Designated Contracting States:
DE FR GB NL

(30) Priority: 09.06.1987 US 59933

(71) Applicant: REED TOOL COMPANY
Houston Texas 77252 (US)

(72) Inventors:
  • Sabados, Michael F.
    Houston Texas 77095 (US)
  • Thompson, Charles M.
    Houston Texas 77069 (US)

(74) Representative: Smith, Norman Ian et al
F.J. CLEVELAND & COMPANY 40-43 Chancery Lane
London WC2A 1JQ
London WC2A 1JQ (GB)


(56) References cited: : 
   
       


    (54) Rotary drag bit having scouring nozzles


    (57) A drag type rotary drill bit (10) having a plurality of cutting elements (38) arranged in a plurality of rows extend­ing radially in a generally arcuate path along the adjacent arcuate surface of the drill bit (10). The bore hole is de­fined by an arcuate concave surface (C) formed by the arcuate rows of the cutting elements (38) upon rotation of the drill bit (10). The centerline (70) of the fluid jet discharged from orifice (66) of scouring nozzle (54) strikes concave surface (C) at a point (P) at an angle between twenty-five (25) degrees and sixty-five (65) degrees with respect to the tangent (T) through point (P) for digging into the concave bottom hole surface (C) in a scouring action and continuing the scouring action after being deflected by the concave surface (C).







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