Continuous Sampling Drill Bit

Abstract

A method includes advancing a drill bit into a formation to form core sample pieces. The drill bit has a central axis and includes a crown defining an inner operative circumference. The crown is configured to form a core sample. A core receiving space is configured to receive the core sample as the drill bit is advanced into the formation. A base surface is spaced from the cutting face along the central axis of the drill bit. The base surface is configured to break apart portions of the core sample to form core sample pieces. The method can further include associating the core sample pieces with respective depths at which the core sample pieces were separated from the formation.

What is claimed is: 
     
         1 - 48 . (canceled) 
     
     
         49 . A method comprising:
 advancing a drill bit into a formation to form core sample pieces, wherein the drill bit having a central axis and comprising:
 a crown defining an inner operative circumference, wherein the crown is configured to form a core sample; 
 a core receiving space that is configured to receive the core sample as the drill bit is advanced into the formation; and 
 a base surface spaced from the cutting face along the central axis of the drill bit, wherein the base surface is configured to break apart portions of the core sample to form core sample pieces; and 
   wherein the core sample pieces are associated with respective depths at which the core sample pieces were separated from the formation.   
     
     
         50 . The method of  claim 49 , wherein the respective depths associated with the core sample pieces account for a delay between when the core sample pieces were separated from the formation and when the core sample pieces are pumped from the borehole. 
     
     
         51 . The method of  claim 49 , wherein the drill bit further comprises:
 a shank defining an inner bore,   at least one conduit that is configured to communicate the core sample pieces from the crown to the inner bore of the shank.   
     
     
         52 . The method of  claim 51 , further comprising;
 flowing cutting fluid toward the cutting face; and   flowing the cutting fluid through the at least one conduit to flush the core sample pieces from the crown to the inner bore of the shank.   
     
     
         53 . The method of  claim 51 , wherein the drill bit is coupled to at least one dual-tube drill rod comprising:
 an outer rod; and   an inner rod positioned within an outer rod,   wherein the inner rod and outer rod cooperate to define an inner annulus, and   wherein the inner rod defines an inner return conduit,   
       wherein the at least one conduit of the drill bit is in communication with the inner return conduit. 
     
     
         54 . The method of  claim 53 , further comprising;
 flowing cutting fluid toward the cutting face via the inner annulus; and   flowing the cutting fluid through the at least one conduit to flush the core sample pieces from the crown to the inner bore of the shank; and   flowing the cutting fluid and the core sample pieces through the inner return conduit.   
     
     
         55 . The method of  claim 49 , wherein the drill bit further defines:
 an inner bore; and   a conduit that is configured to communicate cutting fluid distally through the cutting bore.   
     
     
         56 . The method of  claim 53 , wherein advancing the drill bit into the formation comprises advancing an assembly, the assembly comprising:
 the drill bit;   the at least one dual-tube drill rod coupled to the drill bit; and   an adapter sub, wherein the adapter sub comprises:
 an outer portion; and 
 an inner portion that is disposed within the outer portion, 
 wherein the outer portion and inner portion are coupled together to define an annular passage therebetween, 
   wherein the inner portion of the adapter sub has a distal end that is sealingly received into the second portion of the inner bore of the shank,   wherein the annular passage is in fluid communication with the inner annulus of the at least one dual-tube drill rod.   
     
     
         57 . The assembly of  claim 49 , wherein the base surface comprises a sloped surface that is not coplanar with a plane that is perpendicular to the central axis. 
     
     
         58 . The assembly of  claim 49 , wherein the base surface defines an apex that is radially spaced from the central axis. 
     
     
         59 . The method of  claim 49 , wherein the crown of the drill bit is a second crown, wherein the drill bit comprises:
 a first body comprising a shank defining an inner bore and a first crown having a cutting face, wherein the first crown of the first body defines an outer operative circumference and an inner operative circumference; and   a second body coupled to the first body and comprising a shank and the second crown, wherein the second crown of the second body defines an outer operative circumference and is received within the inner operative circumference of the first body, the crown of the second body having an outer diameter,   wherein the inner operative circumference of the first crown of the first body and the outer operative circumference of the second crown of the second body cooperate to define a first volume, wherein the first volume is configured to receive a tubular core sample,   wherein the shank of the second body has an outer diameter and a first frustoconical outer surface, wherein the outer diameter of the shank along the first frustoconical outer surface increases moving along the central axis in a direction away from the cutting face of the first body, wherein along the first frustoconical outer surface, the outer diameter of the shank of the second body is sufficiently greater than the outer diameter of the second crown of the second body to break the tubular core sample into core pieces as the tubular core sample advances against the first frustoconical outer surface,   wherein the first body and the second body cooperate to define a second volume that is in communication with and positioned proximally of the first volume, wherein the first frustoconical outer surface of the shank of the second body defines at least part of the second volume, and   wherein the first body defines at least one conduit between the second volume and the inner bore of the shank of the first body, wherein the at least one conduit is adapted to enable travel of the core pieces from the second volume to the inner bore of the shank of the first body of the drill bit.   
     
     
         60 . The method of  claim 59 , wherein the shank of the first body has an outer diameter, wherein the inner bore of the shank of the first body comprises a first portion that defines at least one female thread and a second portion that defines a longitudinally extending surface having circular cross sections in planes perpendicular to the central axis, wherein the second portion of the inner bore of the shank of the first body is radially inward of the first portion of the inner bore of the shank of the first body, wherein the shank of the first body defines at least one fluid port that extends to the outer diameter of the shank of the first body from the inner bore of the shank of the first body at a respective inlet that is radially outward of the second portion of the inner bore of the shank of the first body. 
     
     
         61 . The method of  claim 60 , wherein the first portion of the inner bore of the shank of the first body is proximal of the second portion of the inner bore of the shank of the first body. 
     
     
         62 . The method of  claim 60 , wherein the drill bit further comprises a central longitudinal conduit that extends between the at least one conduit and the inner bore of the shank of the first body, wherein the central longitudinal conduit has a diameter, wherein the diameter of the inner operative circumference of the crown of the first body is less than or equal to the diameter of the central longitudinal conduit. 
     
     
         63 . The method of  claim 60 , wherein the drill bit further comprises a central longitudinal conduit that extends between the at least one conduit and the inner bore of the shank of the first body, wherein the diameter of the inner operative circumference of the crown of the first body is greater than the diameter of the central longitudinal conduit. 
     
     
         64 . The method of  claim 60 , wherein the crown of the second body is proximally recessed from the crown of the first body. 
     
     
         65 . The method of  claim 60 , wherein the first body comprises a first segment and a second segment that is threadedly coupled to the first segment. 
     
     
         66 . The method of  claim 63 , wherein the second body defines a plurality of radially extending legs, wherein the second segment defines a plurality of slots that are configured to receive respective radially extending legs of the first body, wherein the radially extending legs of the first body at least partially define the at least one conduit. 
     
     
         67 . The method of  claim 66 , wherein the first body retains the radially extending legs of the second body within respective slots. 
     
     
         68 . The method of  claim 66 , wherein the first body and the second body define respective female screw threads, wherein the first body and the second body are configured to be coupled together via a screw that extends through the respective female screw threads of the first body and the second body.