Molded Composite Mandrel for a Downhole Zonal Isolation Tool

Abstract

A composite mandrel includes a filament-wound composite tube, and composite material molded over the filament-wound composite tube. For example, the composite material includes chopped fibers and a matrix of thermoset resin. The chopped fibers are arranged in layers upon the filament-wound composite tube, and the chopped fibers in each of the layers are randomly oriented along first and second orthogonal directions in each of the layers. The composite material includes at least one sheet of the composite material wound over the filament-wound tube, and at least one strip of the composite material wound over the sheet of the composite material and forming a head on the composite mandrel. An internal cavity of the filament-wound composite tube may provide a lumen for the composite mandrel. The internal cavity may be threaded to receive a removable bridge plug.

1 . A composite mandrel comprising:
 a filament-wound composite tube; and   composite material molded over the filament-wound composite tube.   
   
   
       2 . The composite mandrel as claimed in  claim 1 , wherein the composite material includes chopped fibers and a matrix of thermoset resin. 
   
   
       3 . The composite mandrel as claimed in  claim 2 , wherein the chopped fibers are arranged in layers upon the filament-wound composite tube, and the chopped fibers in each of the layers are randomly oriented along first and second orthogonal directions in said each of the layers. 
   
   
       4 . The composite mandrel as claimed in  claim 1 , wherein the filament-wound composite tube provides a lumen for the composite mandrel. 
   
   
       5 . The composite mandrel as claimed in  claim 4 , wherein an internal cavity of the filament-wound composite tube is threaded to receive a threaded plug for plugging the lumen of the composite mandrel. 
   
   
       6 . The composite mandrel as claimed in  claim 1 , which further includes a plug in one end of the filament-wound composite tube, and wherein the plug is sealed in the filament-wound tube by the composite material molded over the filament-wound tube. 
   
   
       7 . The composite mandrel as claimed over  claim 1 , wherein the composite material includes at least one sheet of the composite material wound over the filament-wound tube, and at least one strip of the composite material wound over said at least one sheet of the composite material, said at least one strip of the composite material forming a head on the composite mandrel. 
   
   
       8 . A composite mandrel for a downhole zonal isolation tool, the composite mandrel comprising:
 a filament-wound composite tube; and   composite molding sheet material wound over and molded over the filament wound tube;   wherein the composite molding sheet material includes chopped fibers and a matrix of thermoset resin, the chopped fibers are arranged in layers over the filament-wound composite tube, and the chopped fibers in each of the layers are randomly oriented along first and second orthogonal directions in said each of the layers; and   wherein the composite molding sheet material includes at least one sheet of the composite molding sheet material wound over the filament-wound tube, and at least one strip of the composite molding sheet material wound over the sheet of the composite molding sheet material and forming a head on the composite mandrel.   
   
   
       9 . The composite mandrel as claimed in  claim 8 , wherein the filament-wound composite tube provides a lumen for the composite mandrel. 
   
   
       10 . The composite mandrel as claimed in  claim 9 , wherein an internal cavity of the filament-wound composite tube is threaded to receive a threaded plug for plugging the lumen of the composite mandrel. 
   
   
       11 . The composite mandrel as claimed in  claim 8 , which includes a plug in one end of the filament-wound composite tube, and wherein the plug is sealed in the filament-wound tube by the composite molding sheet material wound over and molded over the filament-wound tube. 
   
   
       12 . A method of making a molded composite mandrel, said method comprising the steps of:
 (a) winding composite molding sheet material upon an elongated core to form an assembly; and   (b) placing the assembly in a mold in order to mold the composite mandrel.   
   
   
       13 . The method as claimed in  claim 12 , wherein the assembly in the mold is subjected to pressure and heat in order to mold the composite mandrel. 
   
   
       14 . The method as claimed in  claim 12 , wherein the composite molding sheet material includes chopped fibers and a matrix of thermoset resin, and wherein the thermoset resin is set by heat when the assembly is in the mold. 
   
   
       15 . The method as claimed in  claim 12 , wherein the composite mandrel has a central lumen, and the method further includes threading the central lumen for receiving a threaded plug for plugging the central lumen. 
   
   
       16 . The method as claimed in  claim 12 , wherein the elongated core includes a filament-wound composite tube, and wherein the method further includes inserting a plug into one end of the filament-wound composite tube, and winding at least one sheet of the composite molding sheet material over the plug to form the assembly so that the plug becomes sealed in the filament-wound tube by the composite molding sheet material when the composite mandrel is molded in the mold. 
   
   
       17 . The method as claimed in  claim 12 , wherein the composite molding sheet material is wound upon the elongated core to form the assembly by winding at least one sheet of the composite molding sheet material upon the elongated core and then winding at least one strip of the composite molding sheet material upon the at least one sheet of the composite molding sheet material upon the elongated core, wherein said at least one strip of the composite molding sheet material is molded in the mold to form a head on the composite mandrel. 
   
   
       18 . The method as claimed in claimed in  claim 12 , wherein the composite molding sheet material is wound upon the elongated core to form the assembly by placing at least one sheet of the composite molding sheet material on a support, and then placing the elongated core on the sheet and rolling the elongated core to wind said at least one sheet of the composite molding sheet material upon the elongated core. 
   
   
       19 . The method as claimed in  claim 18 , which further includes winding at least one strip of the composite molding sheet material upon said at least one sheet of the composite molding sheet material and said elongated core, and wherein said at least one strip of the composite molding sheet material is molded in the mold to form a head on the composite mandrel. 
   
   
       20 . The method as claimed in  claim 12 , wherein the elongated core includes a filament-wound composite tube and an inner metal core, and the method further includes removing the inner metal core from the filament-wound composite tube after the assembly has been placed in the mold and the composite mandrel has been molded.