Downhole cementing tool assembly

Abstract

A cementing tool assembly comprises a float collar, a cementing plug, and a wiper plug having interconnecting locking ends. The cementing tool assembly is non rotatable in the casing and includes internal frangible cutters which are breakable in compression to aid the shredding of the cementing tool assembly upon completion of the cementing operation.

What is claimed is: 
     
       1. A cementing apparatus for use in cementing a casing string in a well bore, comprising: (a) a float collar incorporated in the casing string, said float collar including a passage extending therethrough;   (b) a cementing plug having a cylindrical body including an axial passage extending therethrough, said cementing plug body further including closure means extending across said axial passage;   (c) a wiper plug having a cylindrical body including wiper means extending about said wiper plug body for wiping the casing as said wiper plug is advanced through the casing;   (d) cooperative interlocking means located on said float collar, said cementing plug and said wiper plug for locking said cementing plug and said wiper plug to said float collar in a nonrotatable position; and   (e) wherein said cementing plug and said wiper plug including frangible internal cutters embedded in said cementing plug and said wiper plug.   
     
     
       2. The apparatus of claim 1 wherein said frangible internal cutters comprise a matrix of frangible pieces embedded in said wiper plug and said cementing plug. 
     
     
       3. The apparatus of claim 2 wherein said closure means in said cementing plug comprises a rupturable diaphragm. 
     
     
       4. The apparatus of claim 3 wherein said cementing plug includes integral wiper means protruding radially outwardly from said body for engaging the surrounding casing. 
     
     
       5. The apparatus of claim 1 wherein said frangible internal cutters comprise elongate, rectangular shaped panes of glass embedded in said wiper plug and said cementing plug. 
     
     
       6. The apparatus of claim 1 wherein said interlocking means comprises a plurality of radially extending teeth formed on the ends of said float collar, said cementing plug and said wiper plug profiled for interlocking engagement to form a nonrotatable assembly in the casing string. .Iadd. 
     
     
       7.  A cementing apparatus for use in cementing a casing string in a well bore, comprising: (a) a float collar incorporated in the casing string, said float collar including a passage extending therethrough;   (b) a cementing plug having a cylindrical body including an axial passage extending therethrough, said cementing plug body further including closure means extending across said axial passage;   (c) a wiper plug having a cylindrical body including wiper means extending about said wiper plug body for wiping the casing as said wiper plug is advanced through the casing; and   (d) cooperative interlocking means located on said float collar, said cementing plug and said wiper plug for locking said cementing plug and said wiper plug to said float collar in a nonrotatable position,   said interlocking means comprising:   a plurality of upstanding substantially perpendicular surfaces extending radially around each end of said cementing plug; radially around one end of said wiper plug; and radially and interiorly around one end of said float collar,   said interlocking means on said float collar further comprising: a recess interiorly inserted around the body of said float collar, said recess defining a line having a curved juncture of an arched surface extending from an edge of the substantially perpendicular surface toward an adjacent surface, thereby defining a plurality of radially extending serrated projecting teeth;   said interlocking means on each end of said cementing plug further comprising: a line having a curved juncture of an arched surface extending from an edge of the substantially perpendicular surface toward an adjacent surface, thereby defining a plurality of radially extending serrated projecting teeth,   whereby, upon interlocking movement of one end of said cementing plug toward said float collar, said substantially perpendicular surfaces of the float collar and the cementing plug are in face-to-face contact and said curved junctures are complimentarily nestled relative to one another. .Iaddend. .Iadd.   
     
     
       8.  The apparatus of claim 7 wherein said closure means in said cementing plug comprises a rupturable diaphragm. .Iaddend. .Iadd. 
     
     
       9.  A cementing apparatus for use in cementing a casing string in a well bore having a float collar incorporated in the casing string, said float collar including a passage extending therethrough, said apparatus comprising: (a) a cementing plug having a cylindrical body including an axial passage extending therethrough, said cementing plug body further including closure means extending across said axial passage;   (b) a wiper plug having a cylindrical body including wiper means extending about said wiper plug body for wiping the casing as said wiper plug is advanced through the casing; and   (c) cooperative interlocking means located on said float collar, said cementing plug and said wiper plug for locking said cementing plug and said wiper plug to said float collar in a nonrotatable position,   said interlocking means comprising:   a plurality of upstanding substantially perpendicular surfaces extending radially around each end of said cementing plug; radially around one end of said wiper plug; and radially and interiorly around one end of said float collar,   said interlocking means on said float collar further comprising: a recess interiorly inserted around the body of said float collar, said recess defining a line having a curved juncture of an arched surface extending from an edge of the substantially perpendicular surface toward an adjacent surface, thereby defining a plurality of radially extending serrated projecting teeth;   said interlocking means on each end of said cementing plug further comprising: a line having a curved juncture of an arched surface extending from an edge of the substantially perpendicular surface toward an adjacent surface, thereby defining a plurality of radially extending serrated projecting teeth,   whereby, upon interlocking movement of one end of said cementing plug toward said float collar, said substantially perpendicular surfaces of the float collar and the cementing plug are in face-to-face contact and said curved junctures are complimentarily nestled relative to one another. .Iaddend.