(19)
(11) EP 1 389 666 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
24.03.2004 Bulletin 2004/13

(43) Date of publication A2:
18.02.2004 Bulletin 2004/08

(21) Application number: 03021140.3

(22) Date of filing: 31.08.1999
(51) International Patent Classification (IPC)7E21B 10/16
(84) Designated Contracting States:
GB IT

(30) Priority: 31.08.1998 US 98466 P

(62) Application number of the earlier application in accordance with Art. 76 EPC:
99945375.6 / 1112433

(71) Applicant: Halliburton Energy Services, Inc.
Carrollton, TX 75006 (US)

(72) Inventor:
  • Chen, Shilin
    Dallas, TX 75248 (US)

(74) Representative: HOFFMANN - EITLE 
Patent- und Rechtsanwälte Arabellastrasse 4
81925 München
81925 München (DE)

   


(54) Force-balanced roller-cone bits, systems, drilling methods, and design methods


(57) A method of designing a roller cone drill bit is disclosed. The method comprises:
  • (a) calculating the force balance conditions of a bit;
  • (b) defining design variables;
  • (c) determine lower and upper bounds for the design variables;
  • (d) defining objective functions;
  • (e) defining constraint functions;
  • (f) performing an optimisation means; and
  • (g) evaluating an optimised cutting structure by modelling.








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