Patent ID: 6679328
Filing Date: 2004-01-20
Classification: E21B

Abstract:
A section milling apparatus for milling of a downhole portion of casing in a well, comprising:a work string; a hydraulic tensioning device having an upper end and a lower end, said upper end being attachable to said work string, said tensioning device being adapted to selectively pull said lower end upwardly toward said work string; a section mill mountable in said section milling apparatus below said lower end of said hydraulic tensioning device, said section mill having a plurality of arms adapted to pivot outwardly and upwardly, said section mill being adapted to hydraulically apply an upward force to pivot said arms outwardly to contact a casing in a cutting relationship; and a fluid flow path through said work string, said fluid flow path being adapted to supply hydraulic pressure to operate said hydraulic tensioning device, and to pivot said arms of said section mill; wherein said section mill is adapted to expand at a lower fluid pressure than a fluid pressure at which said hydraulic tensioning device is adapted to pull upwardly.