Positive cement placement tool

Abstract

Cement slurry injected or delivered into a wellbore during cementing operations can be positively placed with a positive placement tool. The tool can be located along to a casing string and have a mandrel with a tubular centralizer sleeve rotatably fit thereabout, the centralizer sleeve having one or more radial guides extending longitudinally thereon. Reciprocal stroking of the casing string causes a helical drive arrangement, acting between the mandrel and the centralizer sleeve, to drive the centralizer sleeve longitudinally along a length of the mandrel while concurrently rotating the centralizer sleeve thereabout. The rotational movement of the centralizer sleeve provides positive impetus to force the injected cement slurry fully about the casing string.

The embodiments of the invention for which an exclusive property or privilege is claimed are defined as follows: 
     
         1 . A positive placement tool located along a casing string for placing a cement slurry about the casing string within a wellbore comprising:
 a mandrel adapted for location within the casing string;   a centralizer sleeve fit concentrically and movable on the mandrel, the sleeve having one or more radial guides extending generally longitudinally along the sleeve; and   a helical drive arrangement acting between the mandrel and the centralizer sleeve for actuating the centralizer sleeve along a length of the mandrel while rotating the centralizer sleeve thereabout.   
     
     
         2 . The positive placement tool of  claim 1 , wherein the one or more radial guides further comprises two or more radial guides spaced apart circumferentially along an outer surface of the centralizer sleeve. 
     
     
         3 . The positive placement tool of  claim 1 , wherein the one or more radial guides has a profile for urging the cement slurry underneath the casing string. 
     
     
         4 . The positive placement tool of  claim 3 , wherein the profile of each of the one or more radial guides defines a cavity for conveying cement slurry. 
     
     
         5 . The positive placement tool of  claim 3 , wherein the profile is a helical profile extending longitudinally and helically about the centralizer sleeve. 
     
     
         6 . The positive placement tool of  claim 1 , wherein the mandrel is a mandrel sleeve having a bore extending therethrough and adapted for receiving the casing string therethrough, further comprising attachment means for securing the mandrel sleeve to the casing string. 
     
     
         7 . The positive placement tool of  claim 6  wherein the attachment means further comprises set screws. 
     
     
         8 . The positive placement tool of  claim 1 , wherein the helical drive arrangement further comprises:
 at least one helical groove in one or the other of the mandrel or the centralizer sleeve; and   at least one guide pin extending from the other of the centralizer sleeve or mandrel respectively, each guide pin corresponding to and arranged for engaging the helical groove so as to cause the centralizer sleeve to rotate in a first direction and then in an opposite direction as the centralizer sleeve travels uphole and downhole along the mandrel.   
     
     
         9 . The positive placement tool of  claim 8 , wherein the at least one helical groove and the at least one guide pin are two or more corresponding guide pins and helical grooves, each being equally spaced apart circumferentially about the mandrel.