System and method for coupling a drill bit to a whipstock

Abstract

A system and method facilitate drilling of a lateral wellbore by eliminating one or more trips downhole. The system comprises a drill bit optimized for the drilling operation. The drill bit is coupled to a whipstock via a connector, which minimizes interference with the cutting elements of the drill bit. The connector includes a separation device which facilitates disconnection of the drill bit from the whipstock after the whipstock is anchored at a desired downhole location. The separation device is disposed in the connector to minimize the remaining portions of the connector existing after separation of the drill bit from the whipstock which must be milled by the drill bit prior to drilling the lateral wellbore.

What is claimed is: 
     
         1 . An openhole drilling assembly for drilling a lateral borehole, comprising:
 a drill bit having cutting elements configured to at least partially drill a lateral borehole extending from a sidewall of an openhole wellbore, the drill bit having a shank, at least two blades, and at least one junk channel between the at least two blades;   a whipstock with a face configured to guide the drill bit into the sidewall to begin drilling of the lateral borehole, the whipstock further having a top end portion and a back portion, the back portion being opposite the face; and   a connector releasably coupling the drill bit to the whipstock for deployment of the drill bit and the whipstock into the wellbore, the connector including at least one longitudinal member extending from the back portion of the whipstock to the shank of the drill bit, the at least one longitudinal member being at least partially disposed in the at least one junk channel of the drill bit.   
     
     
         2 . The openhole drilling assembly recited in  claim 1 , the connector including a separation device configured to release the drill bit from the whipstock, the separation device being positioned on the longitudinal member and between the shank and the whipstock. 
     
     
         3 . The openhole drilling assembly recited in  claim 2 , the position of the separation device being configured to minimize any portion of the connector remaining after separation and which is to be milled prior beginning drilling of the lateral borehole through the sidewall. 
     
     
         4 . The openhole drilling assembly recited in  claim 1 , the cutting elements including at least one polycrystalline diamond cutter. 
     
     
         5 . The openhole drilling assembly recited in  claim 1 , the connector coupling to the shank of the drill bit. 
     
     
         6 . The openhole drilling assembly recited in  claim 5 , the connector coupling to the shank via a collar. 
     
     
         7 . The openhole drilling assembly recited in  claim 6 , the collar being at least partially disposed in a breaker slot of the shank. 
     
     
         8 . The openhole drilling assembly recited in  claim 1 , the at least one longitudinal member being configured not to interfere with drilling operation of the cutting elements of the drill bit after the release of the drill bit from the whipstock. 
     
     
         9 . The openhole drilling assembly recited in  claim 1 , the at least one longitudinal member being a single longitudinal member. 
     
     
         10 . The openhole drilling assembly recited in  claim 1 , the at least one longitudinal member extending along an axis offset from an axis of the drill bit. 
     
     
         11 . The openhole drilling assembly recited in  claim 1 , the drill bit extending radially outward at least as far as an outer surface of the at least one longitudinal member. 
     
     
         12 . A method of drilling a lateral borehole from an openhole wellbore, comprising:
 positioning a drilling assembly into an openhole wellbore, the drilling assembly including:
 a drill bit having fixed cutters configured to at least partially drill a lateral borehole extending from a sidewall of the openhole wellbore, the drill bit further having at least one junk slot; 
 a whipstock having a face; and 
 a connector releasably coupling the whipstock to the drill  104 , the connector including at least one longitudinal member extending from the whipstock to a position above an uppermost fixed cutter of the drill bit and disposed at least partially within the at least one junk slot, the connector further including at least one shear device positioned along the at least one longitudinal member and between the uppermost cutter and the whipstock; 
   separating the drill bit from the whipstock by shearing the shear device; and   initiating drilling of the lateral borehole by moving the drill bit along the face of the whipstock.   
     
     
         13 . The method of  claim 12 , wherein the at least one longitudinal member is at least partially disposed within the at least one junk channel of the drill bit such that the at least one longitudinal member does not interfere with the fixed cutters drilling the lateral borehole after separation of the drill bit from the whipstock. 
     
     
         14 . The method of  claim 12 , wherein separating the shear device includes shearing a shear bolt. 
     
     
         15 . The method of  claim 12 , wherein the connector further includes a collar coupled to a shank of the drill bit. 
     
     
         16 . The method of  claim 12 , wherein the connector extends from a back surface of the whipstock. 
     
     
         17 . The method of  claim 12 , wherein separating the drill bit from the whipstock includes anchoring the drilling assembly in the openhole wellbore and thereafter applying a rotational or axial force that causes the shear device to shear. 
     
     
         18 . A whipstock, comprising:
 a ramp portion configured to deflect a drill bit;   a back surface opposite the ramp portion; and   a connector configured to releasably couple the back surface of to a drill bit, the connector including:
 a collar configured to extend at least partially around a shank of the drill bit and to be coupled thereto; 
 at least one longitudinal member extending between the back surface and the collar, the at least one longitudinal member being configured to be at least partially disposed within a junk slot of the drill bit; and 
 a shear device positioned along the at least one longitudinal member, and between a top of the ramp portion and an uppermost cutting element of the drill bit. 
   
     
     
         19 . The whipstock of  claim 18 , the connector further including at least one fastener coupling the at least one longitudinal member to the back surface. 
     
     
         20 . The whipstock of  claim 19 , the listener including a weld.