METHOD TO RECOVER AIR-TIGHTNESS OF THREADED CONNECTION IN CASING PIPE INSIDE WELL Russian patent published in 2007 - IPC E21B29/10 

FIELD: oil production, particularly reconditioning of well casings, for instance straightening thereof in producing and injection wells.

SUBSTANCE: method involves eliminating gaps between threads by plastic deformation of threaded pipe part; providing air-tightening of threaded connection by plastic nipple deformation. Plastic nipple deformation is carried out by expansion thereof for value determined from 1%≤ε(σ_y)=d₁(σ_y)-d₀+2·(δ₁(σ_y)-δ₀)/d₀·100%, where ε(σ_t)- relative deformation of nipple in threaded casing pipe connection, %, σ_y - yield point of pipe material, MPa, d₀ - inner nipple diameter in threaded casing pipe connection upstream of flaring, mm, d₁(σ_y) - working diameter of rolling member, mm, δ₀ and δ₁(σ_y) - nipple thickness upstream and downstream of the flaring correspondingly, mm.

EFFECT: increased quality of thread air-tightness and reliability, reduced labor inputs for method realization.

3 dwg, 1 ex