Millable bridge plug system

Abstract

A millable bridge plug system includes a mandrel, an upper cap end, a sealing member, ring members, cone assemblies, slip devices and a lower cap end. The sealing member, ring members, cone assemblies and slip devices are positioned on and around the mandrel. Ring members abut against an upper end and a lower end of the sealing member. The other sides of the ring members abut against the cone assemblies, and the cone assemblies engage respective slip devices. The upper cap end attaches to the first slip device, and the lower cap end attaches to the second slip device. The lower cap end holds the mandrel and second slip device together to resist rotation during milling.

We claim: 
     
         1 . A millable bridge plug system, comprising:
 a mandrel having an upper portion and a lower portion;   an upper cap end attached at said upper portion of said mandrel;   a sealing means positioned around the mandrel between said upper portion and said lower portion;   a plurality of ring members, a first ring member adjacent an upper end of said sealing means and a second ring member adjacent a lower end of said sealing means;   a plurality of cone assemblies, a first cone assembly proximate to said first ring member and a second cone assembly proximate to said second ring member, said first ring member being between said first cone assembly and said sealing means, said second ring member being between said second cone assembly and said sealing means;   a plurality of slip means for extending radially outward and engaging an inner surface of a surrounding borehole, a first slip means mounted around said mandrel and engaging said first cone assembly and a second slip means mounted around said mandrel and engaging said second cone assembly; and   a lower cap end attached at said lower portion of said mandrel,   wherein said upper cap end attaches to said first slip means on a side opposite from said first cone assembly, and wherein said lower cap end attaches to said second slip means on a side opposite from said second cone assembly.   
     
     
         2 . The bridge plug system according to  claim 1 , wherein said lower cap end is comprised of a male connector means, and wherein said second slip means is comprised of a female connector means, said female connector and said male connector means attaching said lower cap end to said second slip means. 
     
     
         3 . The bridge plug system according to  claim 2 , wherein said female connector means and said male connector means attach in at least one engagement of a group consisting of: slide-fit engagement, groove-fit engagement, friction-fit engagement, and snap-fit engagement. 
     
     
         4 . The bridge plug system according to  claim 2 , wherein said male connector means has a shape complementary to a shape of said female connector means. 
     
     
         5 . The bridge plug system according to  claim 4 , wherein said shape of said male connector means is at least one of a group consisting of: rectangular and trapezoidal. 
     
     
         6 . The bridge plug system according to  claim 4 , wherein said shape of said male connector means has a wider portion oriented radially towards an outer surface of said lower cap end. 
     
     
         7 . The bridge plug system according to  claim 4 , wherein said shape of said male connector means forms a locking shoulder abutted against said shape of said female connector means, so as to prevent lateral movement between said second slip means and said lower cap end. 
     
     
         8 . The bridge plug system according to  claim 2 , wherein said male connector means is comprised of a post and a head at an end of said post, said post protruding from an end surface of said second slip means toward said lower cap end, said head having a shape corresponding to a shape of said female connector means. 
     
     
         9 . The bridge plug system according to  claim 8 , wherein said post is comprised of a slot on said end surface of said lower cap end and a connector member, wherein said head is positioned at an end of said connector member, said connector member being removably engaged to said slot, said connector member protruding from said slot in said end surface of said lower cap end toward said second slip means, said head having a shape corresponding to a shape of said female connector means. 
     
     
         10 . The bridge plug system according to  claim 9 , wherein said connector member and said slot being in removable engagement according to at least one of a group consisting of: slide-fit engagement, groove-fit engagement, friction-fit engagement, and snap-fit engagement. 
     
     
         11 . The bridge plug system according to  claim 8 , wherein said post and head form a locking shoulder, said locking shoulder abutting against said shape of said female connector means, so as to prevent lateral movement between said second slip means and said lower cap end. 
     
     
         12 . The bridge plug system according to  claim 1 , wherein said lower cap end is comprised of a male connector means arranged around a perimeter of said lower cap end, and wherein said second slip means is comprised of a female connector means arranged around a perimeter of said second slip means, said female connector and said male connector means being aligned around respective perimeters to attach said lower cap end to said second slip means. 
     
     
         13 . The bridge plug system according to  claim 12 , wherein said female connector means and said male connector means are distributed evenly and correspondingly around respective perimeters. 
     
     
         14 . A millable bridge plug system comprising:
 a mandrel having an upper portion and a lower portion;   an upper cap end attached at said upper portion of said mandrel;   a sealing means positioned around the mandrel between said upper portion and said lower portion;   a plurality of ring members, a first ring member adjacent an upper end of said sealing means and a second ring member adjacent a lower end of said sealing means;   a plurality of cone assemblies, a first cone assembly proximate to said first ring member and a second cone assembly proximate to said second ring member, said first ring member being between said first cone assembly and said sealing means, said second ring member being between said second cone assembly and said sealing means;   a plurality of slip means for extending radially outward and engaging an inner surface of a surrounding borehole, a first slip means mounted around said mandrel and engaging said first cone assembly and a second slip means mounted around said mandrel and engaging said second cone assembly; and   a lower cap end attached at said lower portion of said mandrel,   wherein said upper cap end attaches to said first slip means on a side opposite from said first cone assembly,   wherein said lower cap end attaches to said second slip means on a side opposite from said second cone assembly,   wherein said lower cap end is comprised of a first male connector means, and wherein said second slip means is comprised of a first female connector means, said first female connector and said first male connector means attaching said lower cap end to said second slip means, and   wherein said upper cap end is comprised of a second male connector means, and wherein said first slip means is comprised of a second female connector means, said second female connector and said second male connector means attaching said upper cap end to said first slip means.   
     
     
         15 . The bridge plug system according to  claim 14 , wherein said first female connector means and said first male connector means attach in at least one of a group consisting of: slide-fit engagement, groove-fit engagement, friction-fit engagement, and snap-fit engagement, and
 wherein said second female connector means and said second male connector means attach in at least one of a group consisting of: slide-fit engagement, groove-fit engagement, friction-fit engagement, and snap-fit engagement.   
     
     
         16 . A method of milling a bridge plug system, comprising the steps of:
 forming a bridge plug, said bridge plug comprising:
 a mandrel having an upper portion and a lower portion; 
 an upper cap end attached at said upper portion of said mandrel; 
 a sealing member positioned around the mandrel between said upper portion and said lower portion; 
 a plurality of ring members, a first ring member adjacent an upper end of said sealing member and a second ring member adjacent a lower end of said sealing member; 
 a plurality of cone assemblies, a first cone assembly proximate to said first ring member and a second cone assembly proximate to said second ring member, said first ring member being between said first cone assembly and said sealing member, said second ring member being between said second cone assembly and said sealing member; 
 a plurality of slip devices for extending radially outward and engaging an inner surface of a surrounding borehole, a first slip device mounted around said mandrel and engaging said first cone assembly and a second slip device mounted around said mandrel and engaging said second cone assembly; and 
 a lower cap end attached at said lower portion of said mandrel and to said first slip device on a side opposite from said second cone assembly, 
   installing said bridge plug in a wellbore, said wellbore having inner walls surrounding said bridge plug;   drilling with a removal assembly through said bridge plug, said upper cap, said upper portion of said mandrel, said sealing member, said ring members, said cone assemblies, and said first slip device, while said second slip device, said lower cap end, and said lower portion of said mandrel are held in position.   
     
     
         17 . The method of milling, according to  claim 16 , wherein said lower cap end is comprised of a male connector, and wherein said second slip device is comprised of a female connector, said female connector and said male connector means attaching said lower cap end to said second slip device. 
     
     
         18 . The method of milling, according to  claim 17 , the step of forming said bridge plug comprising:
 attaching said female connector and said male connector in at least one engagement of a group consisting of: slide-fit engagement, groove-fit engagement, friction-fit engagement, and snap-fit engagement.   
     
     
         19 . The method of milling, according to  claim 18 , wherein said female connector and said male connector have complementary shapes. 
     
     
         20 . The method of milling, according to  claim 17 , the step of forming said bridge plug comprising:
 setting said male connector in said lower cap end by removable engagement of at least one of a group consisting of: slide-fit engagement, groove-fit engagement, friction-fit engagement, and snap-fit engagement.