Wellbore composite plug assembly

Abstract

A down hole tool assembly can be installed at a desired location within a subterranean wellbore that is capable of isolating one portion of the wellbore from another, while sealing fluid pressure within the wellbore from at least one direction. The plug assembly can include components constructed of non-metallic material that can be drilled, milled or mechanically broken up more quickly and efficiently than conventional wellbore plugs.

What is claimed: 
     
         1 . A down hole tool assembly for installation in a wellbore comprising:
 a) a mandrel having a proximate end, a distal end, an outer surface and a central through bore;   b) a lower body member affixed to said distal end of said mandrel, wherein said lower body member has a larger outer diameter than said mandrel;   c) a setting cylinder having a central bore, wherein said mandrel is slidably disposed within said central bore of said setting cylinder;   d) a slip assembly disposed between said setting cylinder and lower body member;   e) a seal assembly disposed between said setting cylinder and said body member;   f) a first chamber formed between said mandrel and said setting cylinder;   g) a second chamber formed between said mandrel and said setting cylinder, wherein said first and second chambers are in fluid communication with each other; and   h) a unidirectional seal member disposed between said first and second chambers, wherein said seal member permits fluid to flow from said first chamber to said second chamber, but not from said second chamber to said first chamber.   
     
     
         2 . The down hole tool assembly of  claim 1 , wherein said slip assembly extends radially outward to grip an inner surface of said wellbore. 
     
     
         3 . The down hole tool assembly of  claim 1 , wherein said slip assembly is located either above or below said seal assembly. 
     
     
         4 . The down hole tool assembly of  claim 1 , wherein said slip assembly comprises a plurality of slip members. 
     
     
         5 . The down hole tool assembly of  claim 4 , wherein said slip members can be oriented bi-directionally. 
     
     
         6 . The down hole tool assembly of  claim 1 , wherein said seal assembly extends radially outward to create a fluid pressure seal against the inner surface of said wellbore. 
     
     
         7 . The down hole tool assembly of  claim 1 , further comprising incompressible fluid in said first and second chambers. 
     
     
         8 . The down hole tool assembly of  claim 1 , wherein axial movement of said setting cylinder toward said distal end of said mandrel creates a reduction in volume of said first chamber and increases volume of second chamber. 
     
     
         9 . The down hole tool assembly of  claim 8 , wherein said reduction in volume of said first chamber forces incompressible fluid from said first chamber to said second chamber. 
     
     
         10 . The down hole tool assembly of  claim 1 , wherein said unidirectional seal allows said incompressible fluid to flow from said first chamber to said second chamber, but prevents said incompressible fluid from flowing from said second chamber to said first chamber. 
     
     
         11 . The down hole tool assembly of  claim 1 , wherein said seal assembly is constructed entirely of elastomeric material. 
     
     
         12 . The down hole tool assembly of claim wherein said lower body member further comprises a muleshoe. 
     
     
         13 . The down hole tool assembly of  claim 1  further comprising a setting tool. 
     
     
         14 . The down hole tool assembly of  claim 13 , wherein said setting tool is adapted to apply force to said setting cylinder in a first axial direction and said central mandrel in an opposite axial direction. 
     
     
         15 . The down hole tool assembly of  claim 14 , wherein said setting tool can be selectively removed from a wellbore following anchoring of said down hole tool assembly in said wellbore.