TUBING STRING MAINTENANCE METHOD Russian patent published in 2009 - IPC E21B17/01 B23P6/00 

FIELD: oil-and-gas production.

SUBSTANCE: invention related to oil-and-gas production, can be used in tubing string manufacturing and maintenance. Tubing string maintenance method includes of external and internal pipe surfaces cleaning out of deposits and contamination, linering, ends cuttings, threading, fixing of sleeve and safety units. During external and internal pipe surfaces cleaning, pipe itseff heated up till deposits and contamination became fragile and possible to be destroyed with shot blasting, and internal surface shot blasted. After linering wash linered pipe, dry, shot blast its internal surface, cover internal surface with polymer and heat the pipe up till polymer coating is fixed. After lined pipe ends cut, execute liner ends and tubing string welding and cleaning. Before linering between liner and repaired pipe locate sealing material and after washing and drying heat up lined pipe till sealing material fixed or during internal surface coating heating.

EFFECT: resistance increase against asphalt paraffin deposits inside the well.

3 cl