INSTALLATION METHOD OF BRIDGE CUTTING OFF BELOW-LYING OIL FORMATION Russian patent published in 2013 - IPC E21B33/134 

FIELD: oil and gas industry.

SUBSTANCE: agitator is lowered to the well on a tubing string, through which a sand bridge is inwashed, which covers the perforation interval of below-lying oil productive formation at least by 5-10 m. Then, formation intake capacity is determined, and based on the intake capacity, clay mortar of the corresponding density is prepared. Clay mortar is pumped, the tubing with agitator is lifted to the roof of the above lying formations and the tubing is flushed. Settlements are awaited under action of gravity of large particles and filtration of water from clay mortar till complete blockage of pores of the bridge from sand. Then, the bridge is tested for tightness and repair work is performed. For cement bridge removal the agitator is lowered down to clay bed, clay bed is loosened, and clay bed and sand bridge is removed by flushing.

EFFECT: creation of an easily removable cutting-off bridge resistant to pressure drops with minimum costs of time and number of technological operations.

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