METHOD OF COMPLETING AUXILIARY WELLBORE SHAFT CONSTRUCTION AND RIG TO THIS END Russian patent published in 2010 - IPC E21B33/14 E21B7/04 

FIELD: oil-and-gas industry.

SUBSTANCE: set of inventions relates to oil-and-gas industry, namely to equipment and procedures of contrasting auxiliary wellbores. Proposed device comprises decoupler consisting of adapter with its lower end furnished with branch pipe screwed thereon. Said branch pipe houses sleeve with displacement plug and inner channel to receiver smaller displacement plug. External part of decoupler comprises flared bell with its bottom jointed to auxiliary wellbore casing with cementing assembly secured to its lower end. In compliance with proposed method, preparatory jobs are carried out in auxiliary wellbore, rigs are lowered therein, cementing solution is washed and forced therein, smaller displacement plug is dropped into drill pipe casing, cementing solution is forced into string space and excess cementing solution removed from flared bell. Drilling pipe string is uncoupled from cemented auxiliary wellbore casing to be lifted to day surface.

EFFECT: higher quality of attachment and reliability of separation of formations, lower costs, use of assembly and use, reduced risks.

4 cl, 2 dwg