GB1255557A - Drilling apparatus - Google Patents

Abstract

1,255,557. Core drills. WERF CONRAD EN STORK HIJSCH N.V. and NEDERLANDSE MAATSCHAPPIJ VOOR WERKEN BUITENGAATS (NETHERLANDS OFFSHORE CO). 9 April, 1970 [9 April, 1969], No. 18144/69. Heading E1F. Drilling apparatus for obtaining core samples may be operated by remote control, e.g. when on the sea bed, and consists of a platform 1 (Fig. 1) with an upstanding column 4 on which reciprocates a drilling head 5 with a drive connection 20. The platform also carries a turntable 12 carrying drill pipes 16 in an outer ring and (not shown) core sampling tubes in an inner ring. The turntable can be rotated to align a selected drill tube that it carries with the drill axis; the core tubes are moved between the turntable and the drill axis by reciprocable grabs (not shown). The drill tubes have splined connections 8, 18 with spring-loaded catches (Fig. 3, not shown) holding the joined pipes against relative axial movement. These catches may be released by the inward movement of pivoted arms on a disconnecting device 7. The drill pipe sections have inner and outer walls 32, 31 (Figs. 6 and 7) with drilling mud able to circulate between them, and a core barrel 37 can be inserted down the pipe (the inner wall being smooth) to be secured by latches 48 in the pipe walls. These latches are disengaged, to allow the core barrel to be withdrawn, by increasing the flow rate of drilling mud down the annulus between the inner and outer walls 32, so that plunger 50 is depressed against the spring 51, and engages the latches. The core barrel is raised by means of a tool run down to engage the projection 43 or by pressure of drilling mud. The drilling bit has cutting blades (57, Figs. 8 and 9 not shown) which cut an annulus at the bottom of the bore to leave a central undrilled core which enters the core barrel. The blades are pivoted so that in one direction of rotation, for cutting hard earth, the outer tips of the blades just cut a bore large enough to accommodate the drill string, and the inner tips (62) are within the area of the core barrel (37) so that the core barrel does not have to cut through the earth. The core barrel then rests on the inner tips of the blades. In the other direction of rotation, for soft earth the annulus cut by the blades has a larger outer radius and a larger inner radius and the core barrel is pressed into undrilled earth. The operation of the drilling apparatus may be monitored by television cameras, arranged for example so that one points directly downwards onto the turntable 12 (contacts may also be provided on the turntable to give an electrical signal when a drill pipe is aligned with the drill axis) and so that another is directed towards the disconnected device. A tape measure attached to the drilling head may be in the field of vision of the second camera. In a modification (Fig. 10, not shown) the drilling mud pressure is made to pulsate by a reciprocating piston in a cylinder connected to the mud line, to improve the penetration of the core barrel. In another embodiment (Fig. 11 not shown) the core barrel is dispensed with, and the core is continuously broken and washed out through a flexible hose connected to the drilling head.