Overshot assembly

Abstract

An overshot assembly can include a distal body portion. The distal body portion can have a central axis, a length along the central axis, and an outer surface. An outer surface of the distal body portion can define, along at least a portion of the length, at least one drill string engagement portion having a first radial distance from the central axis of the distal body portion. The drill string engagement portion(s) can be configured to bias against and slide along an inner surface of a drill string. At least one recessed portion can be inwardly spaced from said first radial distance from the central axis. The recessed portion(s) can each be configured to cooperate with the inner surface of the drill string to define a respective flow path along the length of the distal body portion. A plane that is perpendicular to the central axis of the distal body portion can extend through each drill string engagement portion of the at least one drill string engagement portion and each portion of the at least one recessed portion.

1 . An overshot assembly having a longitudinal axis, the overshot assembly comprising:
 a distal body portion having a central axis, a length along the central axis, and an outer surface, wherein the outer surface of the distal body portion defines, along at least a portion of the length:
 at least one drill string engagement portion positioned a first radial distance from the central axis of the distal body portion, wherein the at least one drill string engagement portion is configured to bias against and slide along an inner surface of a drill string, 
 at least one recessed portion that is radially inwardly spaced from said first radial distance from the central axis, wherein said at least one recessed portion is configured to cooperate with the inner surface of the drill string to define a respective flow path along the length of the distal body portion, 
 wherein a plane that is perpendicular to the central axis of the distal body portion extends through each drill string engagement portion of the at least one drill string engagement portion and each recessed portion of the at least one recessed portion. 
   
     
     
         2 . The overshot assembly of  claim 1 , wherein each drill string engagement portion of the at least one drill string engagement portion is a portion of a cylindrical surface. 
     
     
         3 . The overshot assembly of  claim 1 , wherein the at least one drill string engagement portion comprises at least two drill string engagement portions. 
     
     
         4 . The overshot assembly of  claim 1 , wherein the at least one drill string engagement portion comprises three drill string engagement portions. 
     
     
         5 . The overshot assembly of  claim 1 , wherein the drill string engagement portions are equally circumferentially spaced around an inner surface of the distal body portion. 
     
     
         6 . The overshot assembly of  claim 1 , wherein each recessed portion of the at least one recessed portion comprises a planar or generally planar surface. 
     
     
         7 . The overshot assembly of  claim 1 , wherein at least a portion of the at least one recessed portion is inwardly spaced from said first radial distance from the central axis by at least 20% of said first radial distance. 
     
     
         8 . The overshot assembly of  claim 1 , further comprising:
 a proximal body portion that is coupled to the distal body portion, wherein the proximal body portion comprises:
 a first portion; and 
 a second portion that is coupled to the first portion by a swivel joint so that the first portion can swivel relative to the second portion about the longitudinal axis of the overshot assembly, wherein the second portion defines a socket, 
   wherein the distal body portion comprises a pivot element that is received within the socket so that the pivot element is pivotable about an axis that is transverse to the longitudinal axis of the overshot assembly by at least 85 degrees.   
     
     
         9 . A system comprising:
 an overshot assembly having a longitudinal axis and comprising:
 a distal body portion having a central axis, a length along the central axis, and an outer surface, wherein the outer surface of the distal body portion defines, along at least a portion of the length: 
 at least one drill string engagement portion positioned a first radial distance from the central axis of the distal body portion, wherein the at least one drill string engagement portion is configured to bias against and slide along an inner surface of a drill string, 
 at least one recessed portion that is radially inwardly spaced from said first radial distance from the central axis, wherein said at least one recessed portion is configured to cooperate with the inner surface of the drill string to define a respective flow path along the length of the distal body portion, 
 wherein a plane that is perpendicular to the central axis of the distal body portion extends through each drill string engagement portion of the at least one drill string engagement portion and each recessed portion of the at least one recessed portion, and 
 wherein the overshot assembly defines a through bore; 
   a head assembly defining at least one hole that is axially aligned with the through bore of the overshot assembly; and   a locking pin that extends through the through bore of the overshot assembly and the at least one hole of the head assembly to axially retain the head assembly relative to the overshot assembly.   
     
     
         10 . A system comprising:
 an overshot assembly having a longitudinal axis and comprising:
 a distal body portion having a central axis, a length along the central axis, and an outer surface, wherein the outer surface of the distal body portion defines, along at least a portion of the length: 
 at least one drill string engagement portion positioned a first radial distance from the central axis of the distal body portion, wherein the at least one drill string engagement portion is configured to bias against and slide along an inner surface of a drill string, 
 at least one recessed portion that is radially inwardly spaced from said first radial distance from the central axis, wherein said at least one recessed portion is configured to cooperate with the inner surface of the drill string to define a respective flow path along the length of the distal body portion, 
 wherein a plane that is perpendicular to the central axis of the distal body portion extends through each drill string engagement portion of the at least one drill string engagement portion and each recessed portion of the at least one recessed portion; and 
   a head assembly comprising:
 a main body; 
 an adapter that is configured to receive a portion of the overshot assembly, wherein the adapter is at least partly received within the main body; and 
 a fastener that secures the adapter to the main body. 
   
     
     
         11 . The system of  claim 9 , wherein each drill string engagement portion of the at least one drill string engagement portion of the overshot assembly is a portion of a cylindrical surface. 
     
     
         12 . The system of  claim 9 , wherein the at least one drill string engagement portion of the overshot assembly comprises at least two drill string engagement portions. 
     
     
         13 . The system of  claim 9 , wherein the at least one drill string engagement portion of the overshot assembly comprises three drill string engagement portions. 
     
     
         14 . The system of  claim 9 , wherein the drill string engagement portions of the overshot assembly are equally circumferentially spaced around an inner surface of the distal body portion. 
     
     
         15 . The system of  claim 9 , wherein each recessed portion of the at least one recessed portion of the overshot assembly comprises a planar or generally planar surface. 
     
     
         16 . The system of  claim 9 , wherein at least a portion of the at least one recessed portion of the overshot assembly is inwardly spaced from said first radial distance from the central axis by at least 20% of said first radial distance. 
     
     
         17 . The system of  claim 9 , wherein the overshot assembly further comprises:
 a proximal body portion that is coupled to the distal body portion, wherein the proximal body portion comprises:
 a first portion; and 
 a second portion that is coupled to the first portion by a swivel joint so that the first portion can swivel relative to the second portion about the longitudinal axis of the overshot assembly, wherein the second portion defines a socket, 
   wherein the distal body portion comprises a pivot element that is received within the socket so that the pivot element is pivotable about an axis that is transverse to the longitudinal axis of the overshot assembly by at least 85 degrees.   
     
     
         18 . The system of  claim 10 , wherein each drill string engagement portion of the at least one drill string engagement portion of the overshot assembly is a portion of a cylindrical surface. 
     
     
         19 . The system of  claim 10 , wherein the drill string engagement portions of the overshot assembly are equally circumferentially spaced around an inner surface of the distal body portion. 
     
     
         20 . The system of  claim 10 , wherein each recessed portion of the at least one recessed portion of the overshot assembly comprises a planar or generally planar surface.