GB534891A - Improvements relating to core boring apparatus - Google Patents

Abstract

534,891. Core-boring apparatus. ANGLOIRANIAN OIL CO., Ltd., and SEAMARK, L. M. C. June 17, 1939, No. 17785. [Class 85] Core boring apparatus for use in pressure wells comprises means for confining the core in the core band under the pressure prevailing in the borehole before raising the core to the surface. A member k, Fig. 1B, connected to the drill string, is threaded to a piston a, slidabe in cylinder l<SP>1</SP> and pro vided with a hex. agonal stem a<SP>1</SP> engaging in a similar bore in a member l threaded to the cylinder l<SP>1</SP>, whereby rotation is communicated from the drill string through the parts shown in Fig 1C to the drill bit shown in Fig. 1D; the piston a slidably carries pins a<SP>3</SP> which, during boring hold a ball valve a' away from its seat to allow the flushing liquid to flow to the drill bit. The stem a' carries at its lower end an apertured piston guide h threaded to a core barrel c provided at its upper end with a needle valve c<SP>1</SP> and threaded openings c<SP>2</SP> to which test instruments may be connected, a guard c' normally protecting these parts; the lower end of the core barrel carries a fitting g containing a core catcher c<SP>4</SP> and threaded to a valve block d normally supported on packing f<SP>4</SP> in the drill bit. The block d contains a valve j rotatable about a horizontal axis and provided with eccentric trunnions j<SP>1</SP>, packings j' and ball bearings j<SP>2</SP>, the trunnions j<SP>1</SP> engaging holes e<SP>2</SP>, Figs. 1D and 3, in legs e<SP>1</SP> depending from a divided sleeve e whose vertical movement is limited by stop pins b' engaging longitudinal grooves e<SP>3</SP>; the valve j also carries a rubber sealing cap m, Fig. 3, pressed by a spring m<SP>3</SP> and bronze pad m', the cap m and pad m' having apertures for entrance of pressure fluid. In use, after the core has been drilled and entered the core barrel, the drill string is raised slightly, and the ball a<SP>4</SP> falls on to its seat, and the flushing fluid then passes through ports a<SP>7</SP>, Fig. 1B, to raise the piston a and associated parts, whereby the core is broken off, and after the divided sleeve e has reached the upward limit of its movement, the valve j is closed and the sealing cap m is moved against the end of the core barrel to seal off the latter. The whole is then removed from the well, the core barrel is detached, and testing instruments are connected to the openings c<SP>2</SP> or to a plug n<SP>2</SP>, Fig. 7, which replaces a plug n, Fig. 1D, at the lower end of the valve block d.