Millable Fracture Balls Composed of Metal

Abstract

A ball is used for engaging in a downhole seat and can be milled out after use. The ball has a spherical body with an outer surface. An interior of the spherical body is composed of a metallic material, such as aluminum. The spherical body has a plurality of holes formed therein. The holes extend from at least one common vertex point on the outer surface of the spherical body and extend at angles partially into the interior of the spherical body.

What is claimed is: 
     
         1 . A plug for engaging in a downhole seat and being milled out after use, the plug comprising:
 a body having an outer surface and an interior,   the body having a plurality of holes formed therein, the holes extending from at least one common vertex point on the outer surface of the body and extending at angles partially into the interior of the body.   
     
     
         2 . The plug of  claim 1 , wherein the plug is a ball, and wherein the body is spherical. 
     
     
         3 . The plug of  claim 1 , wherein the body is composed of a metallic material. 
     
     
         4 . The plug of  claim 3 , wherein the metallic material comprises aluminum. 
     
     
         5 . The plug of  claim 1 , wherein the at least one common vertex point comprises at least one tap hole defined in the outer surface of the body, and wherein the plurality of holes comprises a plurality of angled holes formed at angles into the interior from the at least one tap hole. 
     
     
         6 . The plug of  claim 1 , wherein the at least one common vertex point comprises common vertex points disposed on opposing sides of the body. 
     
     
         7 . The plug of  claim 6 , wherein the plurality of holes comprises:
 a first set of angled holes formed at angles into the interior from one of the common vertex points on one of the opposing sides; and   a second set of angled holes formed at angles into the interior from the other of the common vertex points on the other of the opposing sides.   
     
     
         8 . The plug of  claim 7 , wherein the first and second sets of angled holes are offset from one another. 
     
     
         9 . The plug of  claim 1 , wherein at least a portion of the holes comprise a filler material disposed therein. 
     
     
         10 . A method of manufacturing a plug for engaging in a downhole seat and being milled out after use, the method comprising:
 forming a body having an outer surface and an interior,   forming a plurality of holes in the body by extending the holes from at least one common vertex point on the outer surface of the body and extending the holes at angles partially into the interior of the body.   
     
     
         11 . The method of  claim 10 , wherein the plug is a ball, and wherein the body is spherical. 
     
     
         12 . The method of  claim 10 , wherein the body is composed of a metallic material. 
     
     
         13 . The method of  claim 12 , wherein the metallic material comprises aluminum. 
     
     
         14 . The method of  claim 10 , wherein extending the holes from the at least one common vertex point on the outer surface of the body comprises forming at least one tap hole in the outer surface of the body, 
     
     
         15 . The method of  claim 14 , wherein extending the holes at angles partially into the interior of the spherical body comprises forming a plurality of angled holes formed at angles into the interior from the at least one tap hole. 
     
     
         16 . The method of  claim 10 , wherein extending the holes from the at least one common vertex point on the outer surface of the body comprises forming tap holes on opposing sides of the body. 
     
     
         17 . The method of  claim 16 , wherein extending the holes at angles partially into the interior of the body comprises:
 forming a first set of angled holes at angles into the interior from one of the tap holes; and   forming a second set of angled holes at angles into the interior from the other tap hole.   
     
     
         18 . The method of  claim 17 , wherein the first and second sets of angled holes are offset from one another. 
     
     
         19 . The method of  claim 10 , further comprising filling at least a portion of the holes with a filler material. 
     
     
         20 . A plug for engaging in a downhole seat and being milled out after use, the plug comprising:
 a body having an outer surface,   a top end of the body having a fin disposed thereon, and   a bottom end of the body opposite the top end having a sealing area on the outer surface, the bottom end being truncated below the sealing area.