Molded swellable packers

Abstract

Embodiments of the present invention provide a swellable packer and a process for manufacturing swellable packers that may be used for sealing off chambers within a well bore. Various embodiments of the present invention include a variety of in situ molding techniques, such as injection molding and compression molding. Furthermore, some embodiments of the present invention include centering end caps about a tube and securing the end caps to the tube. In these embodiments, the swellable packer can then be molded about the tube and the position of the end caps can be used to determine the position of the outer surface of the swellable polymer with respect to the tube.

That which is claimed: 
     
         1 . A method of manufacturing a swellable polymer packer on a support tube, the method comprising the steps of:
 positioning one or more end caps on the support tube, the end caps defining a size and shape;   positioning the end caps and support tube on one or more corresponding supports of an open mold cavity;   closing the mold cavity;   molding swellable polymer in molten form within the mold cavity and around the support tube; and   opening the mold cavity.   
     
     
         2 . The method of  claim 1 , wherein a position of an outer surface of the packer relative to the support tube is determined by a position of the one or more end caps relative to the mold cavity. 
     
     
         3 . The method of  claim 2 , wherein the support tube is out-of-round or bent so as to define a central axis that is not straight. 
     
     
         4 . The method of  claim 1 , wherein the step of molding swellable polymer in molten form within the mold cavity and around the support tube comprises injecting molten polymer into the mold. 
     
     
         5 . The method of  claim 1 , further comprising:
 before closing the mold cavity, layering at least one sheet of a swellable polymer in the open mold cavity.   
     
     
         6 . The method of  claim 1 , wherein the step of molding swellable polymer in molten form within the mold cavity and around the support tube comprises compression molding. 
     
     
         7 . The method of  claim 1 , wherein the supports have replaceable seats. 
     
     
         8 . The method of  claim 1 , wherein the outer surfaces of the end caps are at least partially circular in cross section and the support surfaces of the supports are least partially circular in cross section, and wherein the support surfaces have the same diameter as the outer surfaces of the end caps. 
     
     
         9 . The method of  claim 1 , wherein a cross-sectional dimension of the swellable packer changes along the length of the packer. 
     
     
         10 . A swellable packer comprising:
 a support tube;   one or more end caps secured to the support tube; and   a swellable polymer molded around the tube such that a position of the outer surface of the swellable polymer relative to the tube is determined by a position of the end caps.   
     
     
         11 . The swellable packer of  claim 10 , wherein a cross-sectional dimension of the swellable polymer molded around the tube has a cross-section that changes along a length of the packer. 
     
     
         12 . The swellable packer of  claim 10  wherein at least one end cap is secured to the support tube using set screws. 
     
     
         13 . The swellable packer of  claim 10  wherein at least one end cap defines an inner surface that is at least partially circular and having a diameter that is larger than a nominal outer diameter of a support tube. 
     
     
         14 . The swellable packer of  claim 13  wherein a portion of the swellable polymer is molded between the inner surface of the end cap and the outer diameter of the support tube. 
     
     
         15 . The swellable packer of  claim 10  wherein the support tube is out-of-round or bent so as to define a central axis that is not straight.