| 摘要 |
The invention concerns a core drill, in particular for oil prospecting, comprising a core bit (2), an outer tube (3) supporting the core bit (2), and an inner tube (4) mounted in the outer tube (3) for receiving a core sample, a flowing space (5), provided between the outer (3) and the inner (4) tubes for the passage of the coring fluid means for restricting (6) the fluid passage being arranged in the flowing space (5), on the inner tube (4) front end side (7), and control means (8) being provided for adjusting, from above ground, the restriction means (6) so as to substantially increase said fluid pressure upstream of the restriction means (6).
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