Rod guide for rotating rod strings

Abstract

A rod guide for installation on an intermediate section along a rod without need for access to ends thereof, and which provides a synthetic, low friction surface for reduced contact to either the guide or surrounding tubing. The rod guide has a robust construction for secure attachment to the rod, yet is characterized by ease of installation and replacement. Various outer profiles of low friction surface can be employed, and the low friction surface can be replaced without removing the entire rod guide. Each rod guide can be installed periodically along a rod such as through a work window installed above blow out preventer (BOP) or pack-off element.

What is claimed is: 
     
         1 . A rod guide for installation on a rod string comprising:
 a tubular clamp having
 an inner rod bore and an outer bearing surface about an axis and having an axial height, the clamp being split diametrically along a first separation plane through the rod bore to form a first clamshell clamp portion and a second clamshell clamp portion, 
 the first separation plane extending along the rod bore at an angle to the axis and passing through the axis intermediate the axial height for forming a pair of radial wall faces extending axially along the height of each of the first and second clamshell clamp portions; and 
 interlocking clamp profiles along at least a portion of each of the wall faces and complementary between the first and second clamshell clamp portions for radially securing the clamshell clamp portions together. 
   
     
     
         2 . The rod guide of  claim 1  further comprising a bushing having
 an inner bushing bore fit to the clamp's outer bearing surface and an outer wear surface and having an axial height, the bushing being split diametrically along a second separation plane through the inner bushing bore to form a first clamshell bushing portion and a second clamshell bushing portion, 
 the second separation plane extending along the inner bushing bore for forming a pair of radial bushing wall faces extending axially along the height of each of the first and second clamshell bushing portions; and 
 interlocking bushing profiles along at least a portion of each of the bushing wall faces and complementary between the first and second clamshell bushing portions for radially securing the clamshell bushing portions together. 
 
     
     
         3 . The rod guide of  claim 1  wherein each interlocking clamp profile comprises a complementary dovetail tongue and slot. 
     
     
         4 . The rod guide of  claim 1  wherein:
 each of the pair of wall faces of the first clamshell clamp portion comprises a tongue along at least a portion of its height; and 
 each of the pair of wall faces of the second clamshell clamp portion comprises a slot along its height, 
 the tongues being axially slidable along the slots and complementary for locking the clamshell clamp portions together radially. 
 
     
     
         5 . The rod guide of  claim 2  wherein each interlocking bushing profile comprises a complementary circular bushing tongue and bushing slot. 
     
     
         6 . The rod guide of  claim 5  wherein:
 each of the pair of bushing wall faces of the first clamshell bushing portion comprises a bushing tongue along at least a portion of its height; and 
 each of the pair of bushing wall faces of the second clamshell bushing portion comprises a bushing slot along its height; 
 the bushing tongues being axially slidable along the bushing slots and complementary for locking the clamshell bushing portions together radially. 
 
     
     
         7 . The rod guide of  claim 5  wherein:
 each of the pair of bushing wall faces of the clamshell bushing portions comprises a bushing tongue along at least a portion of its height and a bushing slot along its height; 
 the bushing tongues being axially slidable along the bushing slots and complementary for locking the clamshell bushing portions together radially. 
 
     
     
         8 . The rod guide of  claim 1  wherein the first separation plane angle is self-locking. 
     
     
         9 . The rod guide of  claim 1  wherein the first separation plane angle is greater than about 2 degrees and less than about 16 degrees. 
     
     
         10 . The rod guide of  claim 1  wherein the first separation plane angle is between about 5 to about 6 degrees. 
     
     
         11 . The rod guide of  claim 2  wherein the second separation plane is parallel to, and along, the axis of the bushing bore. 
     
     
         12 . The rod guide of  claim 2  wherein the second separation plane is at an angle to the axis and passes through the axis intermediate an axial height of the bushing. 
     
     
         13 . The rod guide of  claim 12  wherein the second separation plane angle is self-locking. 
     
     
         14 . The rod guide of  claim 2  wherein the bushing is made of a low friction polymer. 
     
     
         15 . The rod guide of  claim 2  wherein at least one of the clamshell clamp portions comprise a flange at a first end. 
     
     
         16 . The rod guide of  claim 15  wherein one of the clamshell clamp portions is of a greater height than the opposing clamshell clamp to form an axially offset retaining structure at a second end and having slots formed therein to receive a retainer and sandwich the bushing between the flange and the retainer. 
     
     
         17 . The rod guide of  claim 16  wherein the retainer is a C-shaped retainer. 
     
     
         18 . The rod guide of  claim 16  wherein the retaining structure and retainer each include one or more complementary pinholes for receiving retaining pins. 
     
     
         19 . The rod guide of  claim 18  wherein the one or more pinholes of the retaining structure are smaller in diameter than the one or more pinholes of the retainer. 
     
     
         20 . The rod guide of  claim 16  wherein the bushing is rotatable about the clamp. 
     
     
         21 . The rod guide of  claim 1  further comprising a bushing having an inner bushing bore fit to the clamp's outer bearing surface and an outer wear surface, wherein the bushing is bonded to the clamp's outer bearing surface. 
     
     
         22 . The rod guide of  claim 21  wherein at least one clamp groove runs axially along the outer bearing surface of the clamp and at least one bushing spline complementary to the at least one clamp groove runs axially along the inner bushing bore. 
     
     
         23 . The rod guide of  claim 2  wherein a plurality of bushing ribs extend generally axially along the outer wear surface of the bushing. 
     
     
         24 . A method for securing a rod guide to a string of rod, comprising:
 locating a first clamshell clamp portion about the rod;   locating a second clamshell clamp portion in opposing relation about the rod, the first and second clamshell clamp portions having an inner bore and interlocking interfaces along a first separation plane through the inner bore, the first separation plane at an angle to the rod's axis;   arranging a first end of one of the first or second clamshell clamp portions with an opposing end of the other of the second or first clamshell clamp portion;   aligning the interlocking interfaces of the respective interlocking interfaces of the first or second clamshell clamp portions;   axially and slidably coupling the first and second clamshell clamp portions until the first or second clamshell clamp portions clamp to the rod.   
     
     
         25 . The method of  claim 24 , further comprising locating a first clamshell bushing portion about the outer bearing surface of the first and second clamshell clamp portions;
 locating a second clamshell bushing portion in opposing relation about the first and second clamshell clamp portions;   coupling the first and second clamshell bushing portions; and   axially restraining the first and second clamshell bushing portions to the first and second clamshell clamp portions.   
     
     
         26 . The method of  claim 24 , further comprising using a striking tool to strike one of the first or second clamshell clamp portions to axially and slidably couple the first or second clamshell clamp portion with the second or first clamshell clamp portion. 
     
     
         27 . The method of  claim 25 , wherein the axially retaining step comprises sandwiching the first and second clamshell bushing portions between a flange and a retainer by inserting a retainer into a retaining structure of the first or second clamshell clamp portion and aligning a one or more retaining pin holes of the retaining structure with a one or more pin holes of the retainer to secure the clamshell bushing portions to the clamp.