Device and method for underreaming a borehole

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EP 0 298 537 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	12.04.1989 Bulletin 1989/15

(43)	Date of publication A2:
	11.01.1989 Bulletin 1989/02

(21)	Application number: 88201228.9

(22)	Date of filing: 15.06.1988

(51)	International Patent Classification (IPC)⁴: E21B 7/28, E21B 10/32, E21B 10/60, E21B 10/46, E21B 4/02, E21B 44/00, E21B 4/18

(84)	Designated Contracting States:
	DE GB NL

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Priority:

25.06.1987 GB 8714921

(71)	Applicant: SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
	NL-2596 HR Den Haag (NL)

(72)	Inventor:
	Zijsling, Djurre Hans NL-2280 AB Rijswijk (NL)

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References cited: :


	Remarks:
	The title of the invention has been amended (Guidelines for Examination in the EPO, A-III, 7.3).

(54)	Device and method for underreaming a borehole

(57) A borehole underreamer device comprises a downhole motor having a rotor part which carries by means of a pivot (2) an elongate clapper body (1) in which a series of abrasive teeth (8) are embedded. In use the device is pulled in upward direction through the borehole while the clapper body describes an orbital motion inside the borehole thereby forcing the teeth to penetrate into the surrounding side wall of the borehole so as to underream the hole.

Search report