METHOD OF OIL AND GAS WELL ABANDONMENT WITH MULTIPLE UNSEALED INTERVALS IN OPERATION COLUMN IN ROUGH TERRAIN Russian patent published in 2012 - IPC E21B33/13 

FIELD: gas and oil production.

SUBSTANCE: invention refers to abandonment of operational, exploratory and prospecting holes with multitude of intervals with production string leakage in out-of-the way places in zone of permafrost rock (PFR). At implementation of the procedure the well is killed, a production tree is disassembled to a case of a pipe head whereon there is installed blowout preventer equipment (BPE). Production string is lifted over perforation interval, cement slurry is injected inside it and pressed through to annular space till the perforation interval is filled. Before cement solidifies, the production string is lowered to the well bottomhole and built-up on top. After cement solidification, through holes are made in the wall of production string, cement slurry is injected inside the string and pressed out through the holes till annular space and tubing string are filled to the well mouth. BPE is dismantled, a transfer reel and central gate are mounted in its place, internal cavities of string and pipe heads and also of a central gate are filled with cement grout; all side branches and an upper flange of the central gate are sealed with blind flanges and a bench mark is set.

EFFECT: raised reliability and ecological safety of gas-oil well abandonment at minimal capital expenditures.

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