Dual Purpose Radial Drilling Tool String for Cutting Casing and Rock in a Single Trip

Abstract

A downhole apparatus for cutting casing and rock when radial drilling defined by a cutting head that includes three or more cutting edges positioned around the cutting head's axis of rotation, at least three of the cutting edges in continuous contact with the face of the material being cut, thereby providing lateral and angular stability to the cutting head, one or more internal fluid passageway within the cutting head and one or more orifices for ejecting drilling-fluid out of the cutting head.

1 . A downhole drilling apparatus for cutting casing and rock when radial drilling defined by a cutting head comprising:
 three or more cutting edges positioned around the cutting head axis of rotation;   at least three of the cutting edges in continuous contact with the face of a material being cut, thereby providing lateral and angular stability to the cutting head;   one or more internal fluid passageway within the cutting head; and,   one or more orifices for ejecting drilling fluid out of the cutting head.   
     
     
         2 . The apparatus of  claim 1 , further comprising a passageway along the center of the cutting head for ejecting the fluid. 
     
     
         3 . The apparatus of  claim 1 , further comprising a wire rope with a lower end and an upper end, the lower end of the wire rope positioned along the centerline of the cutting head and terminates in the cutting head and the upper end of the wire-rope terminates above a flexible portion of the drilling apparatus. 
     
     
         4 . The apparatus of  claim 1 , further comprising at least three inserts that define cutting edges having a cutting face, said inserts partially located in seats upon the cutting head. 
     
     
         5 . The apparatus of  claim 4 , further comprising cutting edges having reliefs behind their cutting faces. 
     
     
         6 . The apparatus of  claim 4 , wherein each point along the cutting edges are positioned within a distance of 0.050″ inches from a diameter of the cutting head. 
     
     
         7 . The apparatus of  claim 4 , wherein at least two of the cutting edges either meet at a point situated along the axis of rotation of the cutting head; or converge toward the axis of rotation to a distance that is less than 7% of the maximum diameter cut by the cutting head. 
     
     
         8 . The apparatus of  claim 4 , wherein at least one insert having different widths along its length. 
     
     
         9 . The apparatus of  claim 4 , having a drilling fluid flow path that is split by at least one insert. 
     
     
         10 . The apparatus of  claim 1 , further comprising curvilinear cutting edges. 
     
     
         11 . The apparatus of  claim 1 , further comprising a chamfer or radius on its cutting edges. 
     
     
         12 . The apparatus of  claim 4 , wherein the material of the cutting inserts is selected from the group consisting of: carbide; tungsten carbide; cubic boron nitrate (CBN); high speed tool steel; cemented carbides, and combinations thereof. 
     
     
         13 . The apparatus of  claim 4 , wherein the insert defines a lower face and at least part of said lower face being unsupported as the insert rests in its seat. 
     
     
         14 . The apparatus of  claim 4 , wherein a lower face of the cutting insert is in direct contact with drilling fluid exiting the cutting head. 
     
     
         15 . The apparatus of  claim 1 , wherein the cutting head has a mid-section diameter less than 97.5% of the diameter of the cutting head maximum diameter defined by the cutting edges. 
     
     
         16 . The apparatus of  claim 1 , further comprising a hard coating applied to the cutting edge to resist wear. 
     
     
         17 . The apparatus of  claim 1 , further comprising the drilling apparatus attached to a flexible drill string comprising a hose running the length of the flexible drill string and said flexible drill string in fluid communication with pumping equipment. 
     
     
         18 . The apparatus of  claim 17 , wherein the flexible drill string is selected from the group consisting of: a series of nesting drive segments; series of links with flexible joints connected by pinning mechanisms; a cable; a counter-wound cable; and combinations thereof. 
     
     
         19 . A system for radial drilling from a wellbore and through a casing, cement and earthen formation in a single trip, said system comprising:
 a whipstock positioned downhole and used to direct a mechanical drilling apparatus outward from the axis of the wellbore at between about 45 to slightly over 90 degrees;   the mechanical drilling apparatus comprising a motor connected to a flexible drill string attached to a cutting head defined in  claim 1 ;   the flexible drill string in fluid communication with surface pumping equipment;   the cutting head and flexible drill string capable of cutting at least  5  feet into an earthen formation.   
     
     
         20 . A method for radial drilling from a wellbore and through a casing, cement and earthen formation with a single mechanical drilling apparatus, said method comprising:
 placing a whipstock downhole to direct the mechanical drilling apparatus outward from the axis of a wellbore;   pumping drilling-fluid down a conduit through a flexible drill string and out a cutting head defined in  claim 1 ;   rotating the flexible drill string and attached cutting head to drill through a casing, cement and at least 5 feet into earthen formation.   
     
     
         21 . A method for forming multiple radials from cased wells in a single trip of a downhole mechanical drilling apparatus comprising:
 securing a whipstock downhole to direct the mechanical drilling apparatus outward from the axis of a wellbore;   pumping drilling fluid down a conduit through a flexible drill string and out a cutting head defined in  claim 1 ;   rotating the flexible drill string and attached cutting head to drill through a casing, cement and at least 5 feet into earthen formation;   retracting the drill into the wellbore, rotating the whipstock and re-securing the whipstock at a second location in the wellbore; and   drilling a second radial through a casing, cement and into the earthen formation with the mechanical drilling apparatus.