DEVICE FOR SEPARATION OF PIPES FALLEN FROM OUTSIDE INTO WELL BY ANODIC DISSOLUTION Russian patent published in 2014 - IPC E21B29/00 

FIELD: oil-and-gas industry.

SUBSTANCE: proposed device comprises cylindrical casing made of dielectric material with tapered inner bottom part. Casing end has circular conical ledge 4. Resilient lugs 6 of cathode are secured to said ledge, said cathode being shaped to truncated cone and composed by thin resilient trapezoidal plates. Wide end of said plates is secured at conical ledge while narrow ends are bent off from casing axis and assembled inside resilient split ring and lap ring-electrode 7. Tow ring bolts 8 are arranged at casing top end for connection to transport system while union 10 is arranged thereat for connection to electrolyte feed system. Four holes 5 in casing wall are made above conical ledge 4 to allow electrolyte to flow from casing inside. Electrolyte feed and DC current source switched on cause electric current the circuit: DC current source "plus", casing string 2, cut pipe 1, electrode system-cathode, electrode gap, conductor 12, DC source "minus". Note here that anodic dissolution of cut pipe wall metal occurs in circle opposite the -cathode 7.

EFFECT: higher reliability, lower applied forces.

3 dwg