CORE SAMPLING TOOL Russian patent published in 2007 - IPC E21B25/02 

FIELD: oil and gas industry, particularly drilling and sample taking devices.

SUBSTANCE: core sampling tool comprises body with upper sub, crown with boring, core receiver made as pipe provided with rotary support and adjustable suspension bracket in upper part thereof. The suspension bracket has retaining ring, adjusting screw connected to axis of rotary support and nut cooperating with the adjusting screw. Circulation orifices are made in the nut. Additional pipe is installed in the core receiver so that the pipe may slide in longitudinal direction. The additional pipe is provided with partition, which cooperates with core coming into the pipe. Core releasing unit comprises shoe connected to core receiver and lever-type core cutter arranged in the shoe. The core cutter comprises body and spring-loaded short and long rotary levers installed in the diametrical body plane. Core releasing unit has sleeve installed in the core cutter body and performing longitudinal movement. Lower sleeve part is made as resilient split collet provided with ledges made on outer surface thereof. The ledges cooperate with lower end of core cutter. Upper sleeve part has ledge on outer surface thereof, is connected to lower part of additional pipe and cooperates with upper end of core cutter body by ledge. Core cutter levers are located in different diametric planes, wherein short levers are over long ones. Upper sub has gate assembly, which indexes core wedging and comprises fixed bush with side and central circulation orifices. Movable bush is slidably installed in upper sub boring. Core receiver is provided with core wedging prevention mechanism made as one or several wedge-like projections arranged on lower end of core receiver suspension bracket nut and located around a circle and as one or several mating similar wedge-like projections formed on upper end of rotary support body and cooperating with them. Rotary support axis is made as stepped bush installed on adjusting screw and sliding in longitudinal direction. The rotary support axis is provided with compression spring having spring force smaller than that of compression spring included in the gate assembly. Distance between lower end of core receiver suspension bracket nut and upper end of rotary support exceeds doubled wedge-like projection height.

EFFECT: improved core removal and reliability of core separation from hole face.

9 dwg