Core drill and coring method

Abstract

Disclosed is a core drill comprising: an external pipe; a coring bit to be rotated by rotation of the external pipe to drill a coring hole and form a core having a core diameter; and an internal coring pipe (1), mounted within the external pipe, to receive a core formed by the coring bit, the internal coring pipe comprising: an internal tubular wall (2) defining a cavity (4) having a diameter substantially the same as the core diameter within which to retain a core formed by the coring bit, one or more viewing openings (8, 9, 10) being formed through the internal tubular wall; and an external tubular wall (3), in which the internal tubular wall is housed coaxially, the internal and external tubular walls being connected to each other so as to form a single-piece double-walled pipe.

Description

technical field

[0001] The present invention relates to core drills and related coring methods. Background technique

[0002] For example, a core drill to be used in oil exploration comprises in a known manner: an annular core bit; an outer tube which supports and rotates the annular core bit; and an inner core tube which will receive the core. The inner core tube is housed coaxially inside the outer tube, for example by means of roller bearings which enable the outer tube to drive the inner tube axially and in rotation around the inner tube without driving it in rotation. In a known manner, a plurality of outer pipes and a plurality of inner pipes can be assembled in succession in a string. The front inner tube (considering the direction of travel of the drill when cutting the core) carries in the usual way a generally split frusto-conical ring system which will The core is held in the cavity of the inner tubing string.

[0003] Core drills of the type described above h...

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