DEVICE FOR OBTAINING GROUND SAMPLES OR CORES

1,206,676. Boring earth &c. INSTITUT FRANCAIS DU PETROLE DES CARBURANTS ET LUBRIFIANTS. 8 March, 1968 [9 March, 1967], No. 11444/68. Heading E1F. In coring apparatus comprising a body 1, a core barrel 8, and a plug 9 within the barrel and having cutters 30, the plug is fixed to the barrel during normal drilling and released from the barrel during coring by a series of operations at least one of which consists in varying the pressure of the flushing fluid which is supplied to the apparatus. The apparatus of Fig. 1 as suitable to be attached to a downthe-hole electric motor and is lowered to the drilling position with parts set as shown. The apparatus is first rotated to move the balls 22 in a piston 15 on a barrel support stem 14 outwardly and the hole is then drilled by continuing the rotation whilst supplying flushing fluid to the apparatus, the fluid passing through apertures 23, 18, 7, 28, 29 into the hole. To set the apparatus for coring the rotation and fluid supply are stopped, the balls returning to their central positions. Fluid is then supplied to move the barrel support stem and a depending connecting member 31 downwardly against springs 16, 33 and to free pawls 46 mounted on the stem from the body. A piston 43 is then moved downwardly to release the pawls, the supply of fluid then being stopped so that the springs raise the stem and member to raise the barrel slightly and close its apertures 28. The raising of the barrel removes balls 10 from grooves 13 to free the plug from the barrel and permit relative rotation between barrel and body. Coring is commenced by resuming rotation and supply of fluid, the fluid passing around the piston through apertures 18 and about the barrel to the hole. In a modification (Fig. 3 not shown) which may be driven from the surface, or by a down the hole motor such as a turbine, the piston is modified so that a set number of pressure pulses must first be given to the fluid to restrict flow through the piston so that an additional pulse will set the apparatus for coring. When the apparatus is set for coring some of the flushing fluid does not pass through the apparatus but is by-passed to the hole. In a further modification the piston has the combined constructions of Figs. 1 and 3.