PLUGGING-BACK DEVICE Russian patent published in 1994 - IPC

FIELD: drilling technique. SUBSTANCE: device, run-in on drill pipes, has container 1 complete with piston 2 which divides it into head end 3, working chamber 4 filled with a plug-in material, and a jet pulser. The jet pulser consists of upper adapter 14 having supply channel 15, body 16 with drain windows 17, nozzle chamber 18, and outlet channel 22. Channel 15 is hydraulically connected to the string hollow. Nozzle chamber 18 is connected to string-borehole annulus through windows 17. Channel 22 is connected to head end 3. Inlet hydraulic gate is mounted in the upper section of body 16 between adapter 14 and chamber 18. The gate comprises sleeve 32 and bushing 33 secured on it in the initial position by locker 35. Sleeve 32 is mounted inside body 16 coaxially and in spaced relation and is rigidly connected to it. Bushing 33 is provided with an axial channel, radial openings 34 in upper section, and a return valve in the lower section of the axial channel. Bushing 33 is mounted in sleeve 32 for axial motion and, in its working position, for bypassing of washing fluid from channel 15 to chamber 18. As the device is lowered in the well, the string is filled with fluid through axial channel of bushing 33. As the device reaches the plugging-back zone, the mud pump is put into operation, the string is poured full with the fluid, and the rotation is switch on. The locker 35 acts which results in bushing 33 lowering permitting thus the fluid to enter the pulser. Pulse jet produced by the pulser acts upon piston 2. The material is pushed out of the chamber into the well. EFFECT: increased reliability of plugging-back; reduced time. 6 dwg