Roller cone drill bit, method of designing the same and rotary drilling system - Patent 1371811

(19)

(11)

EP 1 371 811 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	02.01.2004 Bulletin 2004/01

(43)	Date of publication A2:
	17.12.2003 Bulletin 2003/51

(21)	Application number: 03021139.5

(22)	Date of filing: 31.08.1999

(51)	International Patent Classification (IPC)⁷: E21B 10/16

(84)	Designated Contracting States:
	GB IT

(30)

Priority:

31.08.1998 US 98442 P

(62)	Application number of the earlier application in accordance with Art. 76 EPC:
	99945376.4 / 1117894

(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)	Roller cone drill bit, method of designing the same and rotary drilling system

(57) A method of designing a roller cone bit is disclosed. The method comprises the steps of:

calculating the trajectory of at least one tooth on each cone through formation material at the cutting face; and
jointly optimising both the orientations of said teeth and the width of uncut rings on said cutting face, in dependence on said trajectory.