CORE-TAKING TOOL Russian patent published in 2008 - IPC E21B25/08 

FIELD: oil and gas well drilling, particularly well drilling with core taking.

SUBSTANCE: core-taking tool comprises body connected with sub 6 in upper part thereof for tool attaching to pipe string. Core-taking tool also has drilling head 3 with boring 4, core-lifting means 8 made as pipe 9 and provided with suspended support 22, as well as adjustable suspension means 35 in upper part thereof. Core separation unit, which separates core from bottom, includes collet corer 13 and lever corer 12 movably arranged in shell 11, which is connected with lower part of core lifting pipe 9 by means of bayonet connector 10. Core receiver 8 is installed in tool body 1 and cooperates with core entry control valve 40. The valve 40 is made as fixed bush 41 installed in the sub and provided with side circulation orifices 42 and with central channel 43 to arrange head 44 so that the head 44 may slide in axial direction. Cap 44 is secured to head 44 through detachable connection. Channels are formed in lower shell 11 part in side wall cooperating with boring 4 of drilling head and are distributed along a circle. Conical cavity is created over the channels. Said conical cavity cooperates with mating conical cavity made in boring 4 end to create valve coupling. Bypass valve 29 is formed in core receiver 8. Upper 31 and lower 32 seats have the same standard dimensions. Ball 33 is installed between the seats 31, 32 so that the ball alternately cooperates with the seats. Bayonet connection 10 to secure shell 11 with core lifting pipe 9 includes two cylindrical extensions made on core-lifting pipe 9 so that they are symmetrical about axis and figured slots cooperating with the slots and forming mirror images of each other. The slots are created in shell wall. Each of figured slots consists of vertical sections having the same width. The first section is opened in shell end. The second section is sealed. Said slots are connected with each other through slot having equal width and extending from the first slot towards the second one so that angle less than 90° is created in-between.

EFFECT: improved core recovery, increased operational reliability, decreased operational costs and extended operational capacities.

5 dwg