GB473172A - A device for taking cores from a borehole - Google Patents

Abstract

473,172. Deep boring. NAAMLOOZE VENNOOTSCHAP DE BATAAFSCHE PETROLEUM MAATSCHAPPIJ. Jan. 21, 1937, No. 1870. Convention date, Feb. 8, 1936. Addition to 451,825. [Class 85] In a device for raising cores through the drill tubes by the flushing fluid by reversing the flow thereof, the surface on which the reversed flow acts is placed above the core barrel. In Figs. 1a and 1b, the core barrel 25, carrying vent valve 20, is normally held by pawls 14 engaging a collar 13 and locked by a head 10<1> on a slidable rod 10<11> provided with a stop nut 17 ; integral with the head 10<1> is an apertured tube 10 limiting downward movement of the head and threaded to a tubular member 5 containing a seat 6 below which a ball valve 7 normally floats on a spring 9. An elastic piston 4 is carried by the member 5. During drilling, the flushing fluid passes down through member 5, past valve 7 and around the core barrel. On reversing the flow, valve 7 closes and the pressure acts on piston 4 first to raise rod 10<11> to release the pawls 14, and then to raise the core barrel. If the drill pipe is not flush jointed internally, the length of the aggregate must be such that at least one of two successive reduced parts of the bore is closed by the piston or some part such as the core barrel. In Fig. 2, the piston 4 forms part of a separate device including pivoted jaws 37 adapted to engage a head 40 on the core barrel and to be locked by an enlargement 33<1> on a rod 33 ; the device is forced downwards by the flushing fluid and when the jaws 37 contact the head 40, spring 35 yields and enlargement 33<1> clears the jaws to allow the latter to engage the head.