A Section Mill And Method Of Removing A Section Of A Well Tubing

Abstract

A section mill (10) and method of removing a section of tubular (150) from a well. The section mill includes elongate blades (14) which have a cutting structure (66) extending along at least a portion of a length from a first edge (62) and at least a portion of a width from a second edge (64) of the elongate cutter blade, the second edge being longer than the first edge, the first and second edges being perpendicular to each other. The blades are moved axially and radially relative to the tubular body (12) to arrange the second edge parallel to the central longitudinal axis (13) for milling Operation of the mill is in an upwards direction using a hydraulic tensioning device to provide a constant load so that milling of tubular can be achieved in a rigless arrangement.

1 . A section mill for removing a section of well tubing comprising:
 a tubular body;   a plurality of elongate cutter blades, each elongate cutter blade including a cutting structure extending along at least a portion of a length from a first edge and at least a portion of a width from a second edge of the elongate cutter blade, the second edge being longer than the first edge, the second edge being longer than the first edge;   and an actuating mechanism to move the elongate cutter blades axially and radially relative to the tubular body between:   a first position wherein the elongate cutter blades are located inside the tubular body with the second edge being substantially parallel to the central longitudinal axis; and   a second position wherein the cutting structure is located outside the tubular body with the second edge being substantially parallel to the central longitudinal axis.   
     
     
         2 . The section mill according to  claim 1  wherein the actuating mechanism comprises:
 a first profile on a third edge opposite the second edge on each elongate cutter blade; 
 a second profile on an inner surface of the tubular body; 
 and a piston arranged to move the elongate cutter blade axially with respect to the tubular body so as to contact the first and second profiles and thereby move the elongate cutter blades from the first position to the second position. 
 
     
     
         3 . The section mill according to  claim 1  or  claim 2  wherein the tubular body includes a plurality of longitudinally arranged elongate recesses spaced around a circumference of the tubular body wherein an elongate cutter blade is located in each recess. 
     
     
         4 . The section mill according to  claim 1  wherein there are three elongate cutter blades. 
     
     
         5 . The section mill according to  claim 1  wherein each elongate cutter blade includes a slot, in which a guide pin is located and can move therein. 
     
     
         6 . The section mill according to  claim 5  wherein each elongate cutter blade includes two slots in which guide pins are located respectively. 
     
     
         7 . The section mill according to  claim 2  wherein the piston is arranged on the central longitudinal axis in the tubular body. 
     
     
         8 . The section mill according to  claim 2  wherein there is a chamber arranged at a first end of the piston. 
     
     
         9 . The section mill according to  claim 8  wherein there are one or more flow ports through the tubular body accessing the chamber. 
     
     
         10 . The section mill according to  claim 1  wherein the section mill includes a locking mechanism actuable to hold the elongate cutter blades in the second position. 
     
     
         11 . The section mill according to  claim 2  wherein the second profile includes a ramp at a leading end thereof to move the elongate cutter blade to a mid-position between the first and second positions, wherein in the mid-position an apex where the first and second edges meet provides a cutting edge to cut through the tubing prior to milling. 
     
     
         12 . The section mill according to  claim 2  wherein the section mill further comprises a mill deployed indicator to let an operator know that the elongate cutter blades have reached the second position, the mill deployed indicator comprising a selectively sealed flow path through the piston wherein upon opening of the flow path a change in pressure will be detected at surface. 
     
     
         13 . (canceled) 
     
     
         14 . A method of removing a section of well tubing, comprising the steps:
 (a) providing a work string with a section mill according to  claim 1 , the section mill located in the first position, and a hydraulic tensioning device, the hydraulic tensioning device being adapted to pull a lower end of the hydraulic tensioning device upwardly toward the work string, and the section mill being attached below the lower end of the hydraulic tensioning device;   (b) lowering the work string, the section mill and the hydraulic tensioning device into a tubing to be milled;   (c) pumping fluid through the work string to actuate the section mill and thereby move the elongate cutter blades to the second position to locate the first edge at a lower end of the tubing;   (d) rotating the section mill to mill the tubing;   (e) pumping fluid through the work string to actuate the hydraulic tensioning device so that a lower end of the hydraulic tensioning device is hydraulically pulled upwardly toward the work string, thereby pulling the section mill upwardly; and   (f) removing a section of the tubing by milling in an upward direction.   
     
     
         15 . The method of removing a section of well tubing according to  claim 14  wherein the work string is lowered from a floating vessel. 
     
     
         16 . The method of removing a section of well tubing according to  claim 14  wherein the method includes the steps of:
 (g) pumping fluid through the work string to actuate the section mill and thereby move the elongate cutter blades to a mid-position to locate a cutting edge, being an apex where the first and second edges, against the tubing; and 
 (h) rotating the section mill to cut the tubing. 
 
     
     
         17 . The method of removing a section of well tubing according to  claim 16  wherein steps (g) and (h) are undertaken prior to step (c). 
     
     
         18 . The method of removing a section of well tubing according to  claim 14  wherein the method includes the step of locking the elongate cutter blades in the second position. 
     
     
         19 . The method of removing a section of well tubing according to  claim 14  wherein the method includes the step of providing a signal at surface that the elongate cutter blades have reached the second position. 
     
     
         20 . The method of removing a section of well tubing according to  claim 14  wherein the method includes the step of rotating the work string to rotate the section mill. 
     
     
         21 . The method of removing a section of well tubing according to  claim 14  wherein the method includes the step of actuating a downhole motor to rotate the section mill.