DRILLING ASSEMBLY WITH SLIME BACK FLUSH Russian patent published in 2012 - IPC E21B4/14 E21B10/38 

FIELD: oil-and-gas production.

SUBSTANCE: drilling assembly comprises casing with downhole packer, hammer, drilling bit with central slime intake channel and outer grooves to make exhaust channels with aforesaid casing and downhole packer. Said exhaust channels are communicated with well bottom via inclined blowoff holes directed from periphery to drilling bit center. Downhole packer bottom is furnished with annular chamber communicated with well bottom via inclined blowoff holes.

EFFECT: higher efficiency of well cleanout.

2 dwg