Near-Bit Borehole Opener Tool and Method of Reaming

Abstract

The present disclosure relates to a near-bit borehole opener (reamer) tool and a method of drilling a wellbore comprising: (a) disposing in the wellbore a tool string; (b) lowering and rotating the tool string and drilling a first portion of the wellbore having a first diameter with the drill bit, wherein the at least one cutter assembly of the borehole reamer is in a closed position; (c) reaming with the second borehole reamer a portion of the wellbore to a second diameter larger than the first diameter, wherein a rat hole portion of the wellbore is not reamed with the second borehole reamer, said rat hole portion of the wellbore having the first diameter; (d) extending the at least one cutter assembly of the first borehole reamer; and (e) concurrently rotating and moving the first borehole reamer up or down in the rat hole portion of the wellbore with the first diameter and abrading and cutting away the wellbore wall contacted by the at least one cutter assembly of the first borehole reamer assembly, thereby enlarging the diameter of a portion of the rat hole portion of the wellbore.

1 . A method of drilling a wellbore comprising:
 (a) disposing in the wellbore a tool string including a drill bit on a distal end of the tool string, a first borehole reamer assembly having at least one cutter assembly, said first borehole reamer disposed adjacent to the drill bit, a downhole remote steering assembly disposed in the tool string above and proximal to the first borehole reamer assembly, and a second borehole reamer assembly with at least one cutter assembly disposed in the tool string above the downhole remote steering assembly;   (b) lowering and rotating the tool string and drilling with the drill bit a first portion of the wellbore having a circumferential wall and a first diameter, wherein the at least one cutter assembly of the first borehole reamer are in a closed position;   (c) reaming with the second borehole reamer a portion of the wellbore to a second diameter larger than the first diameter, wherein a rat hole portion of the wellbore is not reamed with the second borehole reamer, said rat hole portion of the wellbore having the first diameter;   (d) extending the at least one cutter assembly of the first borehole reamer; and   (e) concurrently rotating and moving the first borehole reamer up or down in the rat hole portion of the wellbore with the first diameter and abrading and cutting away the wellbore wall contacted by the at least one cutter assembly of the first borehole reamer assembly, thereby enlarging the diameter of a portion of the rat hole portion of the wellbore.   
     
     
         2 . The method of  claim 1  further including disposing a MWD/LWD assembly in the tool string above the downhole remote steering assembly and below the second borehole reamer. 
     
     
         3 . The method of  claim 1  wherein the first borehole reamer and the drill bit are joined to each other by welding before they are disposed in the tool string. 
     
     
         4 . The method of  claim 1  wherein a body of the first borehole reamer and a body of the drill bit are formed integrally. 
     
     
         5 . The method of  claim 1  wherein the cutter assemblies of the second borehole reamer are opened in step (b) and steps (b) and (c) are conducted concurrently. 
     
     
         6 . The method of  claim 1 , further including: prior to beginning step (c) pulling up the tool string out of the rat hole portion of the wellbore and wherein in step (e) the first borehole reamer assembly is rotated and moved in a downward direction into the rat hole portion thereby reaming a portion of the rat hole portion to a larger diameter. 
     
     
         7 . A bottom hole assembly for use in a wellbore comprising:
 a borehole reamer assembly including a body adapted at an upper end to be connected to a tool string including a downhole remote steering assembly, and adapted at a lower end to be connected to a drill bit;   said borehole reamer assembly further including at least one cutter assembly adapted to extend in a radial direction away from a longitudinal axis of the body, said cutter assembly further adapted to abrade and cut away a circumferential wall of the wellbore contacted, thereby enlarging a diameter of the wellbore in an area contacted by the cutter assembly.   
     
     
         8 . The bottom hole assembly of  claim 7  wherein the borehole reamer assembly adapted at a lower end to connect to a drill bit comprises a body of the borehole reamer welded at a lower end of the body to a drill bit body thereby forming a unitary reamer drill bit combination tool. 
     
     
         9 . The bottom hole assembly of  claim 7  wherein a body of the borehole reamer and a body of the drill bit are formed integrally. 
     
     
         10 . The bottom hole assembly of any of  claim 7  wherein the tool string further includes a MWD/LWD assembly disposed in the tool string above the downhole remote steering assembly. 
     
     
         11 . The bottom hole assembly of any of  claim 7  wherein the tool string further includes a second borehole reamer assembly disposed in the tool string above the downhole remote steering assembly or the MWD/LWD assembly. 
     
     
         12 . The bottom hole assembly of any of  claim 7  wherein the tool string disposed above the borehole reamer assembly further includes a second borehole reamer assembly disposed in the tool string above both the RSS assembly and the MWD assembly. 
     
     
         13 . The method of drilling a wellbore comprising:
 (a) disposing in the wellbore a tool string including a drill bit on a distal end of the tool string, a borehole reamer assembly having at least one cutter assembly, said borehole reamer disposed adjacent to the drill bit;   (b) lowering and rotating the tool string and drilling a first portion of the wellbore having a first diameter with the drill bit, wherein the at least one cutter assembly of the borehole reamer is in a closed position;   (c) extending the at least one cutter assembly of the first borehole reamer; and   (d) concurrently rotating and moving the borehole reamer up or down in a rat hole portion of the wellbore with the first diameter and abrading and cutting away a circumferential wall of the wellbore wall contacted by the at least one cutter assembly of the borehole reamer assembly, thereby enlarging a diameter of a portion of the rat hole portion of the wellbore.   
     
     
         14 . The method of  claim 13  further including disposing a downhole remote steering assembly in the tool string above and proximal to the first borehole reamer assembly. 
     
     
         15 . The method of  claim 14  further including disposing a MWD/LWD assembly in the tool string above the downhole remote steering assembly. 
     
     
         16 . The method of  claim 15  further including disposing a second borehole reamer assembly with at least one cutter assembly disposed in the tool string above the downhole remote steering assembly. 
     
     
         17 . The method of  claim 16  further including joining the first borehole reamer and the drill bit to each other by welding before they are disposed in the tool string. 
     
     
         18 . The method of  claim 16  further including forming integrally a body of the first borehole reamer and a body of the drill bit. 
     
     
         19 . The method of  claim 16  further including: prior to step (c), reaming with the second borehole reamer a portion of the wellbore to a second diameter larger than the first diameter, wherein a rat hole portion of the wellbore is not reamed with the second borehole reamer, said rat hole portion of the wellbore having the first diameter. 
     
     
         20 . The method of any of  claim 19  further including opening the cutter assembly of the second borehole reamer in step (b) and steps (b) and (c) are conducted concurrently. 
     
     
         21 . The method of any of  claim 13  further including: prior to beginning step (c) pulling up the tool string out of the rat hole portion of the wellbore and in a step (e) rotating the first borehole reamer and moving in a downward direction into the rat hole thereby reaming a portion of the rat hole to a larger diameter. 
     
     
         22 . A bottom hole assembly for use in a wellbore comprising:
 a borehole reamer assembly including a body having an attachment structure for securing an upper end to a tool string including a downhole remote steering assembly, said borehole reamer attachable at a lower end to a drill bit, said borehole reamer assembly further including at least one cutter assembly extending in a radial direction away from a longitudinal axis of the body, said cutter assembly further including at least one cutter element operable to abrade and cut away a wellbore wall contacted by the cutter, and thereby enlarge the diameter of the wellbore in the area contacted by the cutter.   
     
     
         23 . The bottom hole assembly of  claim 22  wherein the borehole reamer assembly comprises a unitary reamer drill bit combination tool having a body of the borehole reamer welded at a lower end of the body to a drill bit. 
     
     
         24 . The bottom hole assembly of  claim 22  wherein the borehole reamer assembly comprises a unitary reamer drill bit combination tool having an integrally formed borehole reamer body and drill bit body. 
     
     
         25 . The bottom hole assembly of any of  claim 22  wherein the tool string further includes a MWD/LWD assembly disposed in the tool string above the downhole remote steering assembly. 
     
     
         26 . The bottom hole assembly of any of  claim 22  wherein the tool string further includes a second borehole reamer assembly disposed in the tool string above the downhole remote steering assembly or the MWD/LWD assembly. 
     
     
         27 . The bottom hole assembly of any of  claim 25  wherein the tool string disposed above the borehole reamer assembly further includes a second borehole reamer assembly disposed in the tool string above both the RSS assembly and the MWD assembly. 
     
     
         28 . The bottom hole assembly of any of  claim 22  wherein an overall longitudinal length of the borehole reamer assembly for reaming a 16⅞ diameter hole is less than or equal to 60 inches.